BE679615A - - Google Patents

Description

  

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   The present invention relates to refractory compositions; it relates more particularly to molybdenum, tungsten, chromium, rhenium and their alloys in which is dispersed aluminum nitride, titanium nitride, zirconium nitride, tantalum nitride, haf nitride - nium, niobium nitride, vanadium nitride or a mixture of these substances. The invention further relates to the preparation of these dispersions, their use as refractories at elevated temperatures as well as for making cutting tools, and the preparation of nitrides used in the dispersions.



   The refractory dispersions according to this invention are hard and strong, and resistant to chemicals, thermal shock, impact and high temperatures. They exhibit high electrical and thermal conductivity and are superior to erosion resistance. They can be used in structural applications, in anti-corrosive and anti-erosion installations for chemical processes, to fabricate electrodes. high temperature, dies or dies, wire guides, bearings and gaskets - and in many other fields in which refractory materials are conventionally used.

   Under the. Form of bits of tools and cutting tools used for cutting, grinding, forming, drilling and stamping very hard metals or alloys, these dispersions exhibit high resistance to wear and tear. crater formation and resist welding to loose workpieces, even at high speeds.

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   The present invention provides a homogeneous dispersion of a refractory material consisting of a metal selected from molybdenum, tungsten, chromium, rhenium and their alloys in which is dispersed a nitride selected from titanium nitride, zirconium nitride , tantalum nitride, hafnium nitride, aluminum nitride, vanadium nitride, niobium nitride, and mixtures thereof.



   In addition to molybdenum, tungsten, chromium, rhenium and their alloys, minor amounts of other conventional alloying agents can be used with these metals in the dispersions of the invention as will be further explained. in detail below.



   The dispersions of this invention are prepared by intimately mixing the nitride to be used, in the form of very fine particles3 with the metal to be used, also in the form of very fine particles, until a homogeneous dispersion is obtained. This homogeneous powder can then be heated and pressed into the desired shape and with the desired degree of density.



   The preparation of powder dispersions is important because the properties of the refractory dispersions formed from these powders depend to a large extent on the composition of the powder. For example, the homogeneity of the mixed dispersion of the metal and the nitride, the final particle and crystalline size of the nitride and the metal, and the proportional amounts of the metal and the nitride are critical in achieving the desired properties in the metal. refractory dispersions. of this invention and are largely determined by the powder which is used to form the refractory dispersion.

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   The particle size of the metal and the nitride to be incorporated in the powder dispersions of this invention should be as small as possible. The preferred maximum particle size is about 5 microns. The desired homogeneity of the dispersion is much easier to achieve as the particle size decreases and it is advantageous if the components have an average particle size of less than 10 microns.



   If the disperse powders are to be used to form very strong refractories for making cutting tools and bits, it is preferred that the average particle size of the components is less than 1 micron. Such a particle size significantly assists in achieving the degree of toughness, hardness and wear resistance.



   Refractory dispersions can be formed from mixed powdered dispersions of the nitride and the metal in which there are about 1 to 99 parts by volume of nitride per part of metal. If the amount of nitride in a powder is less than 1 part by volume per part of metal, the hardness of a refractory dispersion made from that powder is less than desired. Amounts of nitride in powders greater than 99 parts per part of metal tend to significantly decrease the improved strength of refractories made from such powders.



   A preferred amount of nitride in powder dispersions is between 1.5 and 19 parts by volume per part of metal. Restricting the amount of the nitride to less than 19 parts by volume increases the probability of obtaining metal continuity in the refractory dispersion to be formed, and in turn, the probability of obtaining impact resistance, solidity, a striking hardness.

   Conversely, the presence of at

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 at least 1.5 parts of nitride by volume per part of metal in the powder provides hardness, wear resistance, resistance to chemicals, etc., in a dispersion made from this powder, which characteristics make it very attractive for refractory uses such as cutting tools and drill bits.



     One of the preferred embodiments is a powder dispersion in which the nitride particles are separated from each other by particles of the metal. This prevents or decreases the agglomeration or aggregation of the discrete nitride particles during the manufacture of the refractory dispersions.



   Another preferred embodiment is a dispersion in which the discrete particles are uniformly dispersed in the metal which is present as a phase or continuous vehicle separating the discrete nitride particles. Such a distribution of the metal ordinarily provides much improved mechanical properties in a refractory dispersion, making it much more attractive to use in making cutting tools and bits.



   Another preferred embodiment is a mixed dispersion or interdispersion in which there is a limited degree of interrelation in a continuous vehicle, or network, of two of the main phases of the invention. In such a structure, both the nitride phase and the metal phase are mixed continuous, an interpenetrating network of each phase being simultaneously present. Such compositions show most of the salient properties when the individual crystallites of the interpenetrating lattices, although related to each other.
The other, remain quite small and discernible.

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   It should be noted that a distribution of the nitride and the metal as described in the previous three paragraphs is not essential, since remarkable refractories can be produced in the absence of such a distribution. .



   It is desirable that both the nitride and the metal used possess a high degree of chemical purity. In particular it is desirable to avoid the presence, in both constituents, of oxygen, carbon, nitrogen, boron, silicon or sulfur either in uncombined form or in the form of compounds having a free energy of formation per atom less than that of the corresponding oxides, carbides, nitrides, borides, silicides or sulphides of molybdenum, tungsten, chromium, rhenium or their alloys.



   Other such elements or compounds in a form and in amounts which would react with or dissolve the metal used during the manufacture of the refractory dispersion so as to impart an undesirable brittleness to the metal, should also be avoided.



   It is sometimes difficult to prepare and maintain the very finely divided powders of this invention completely free from impurities such as oxygen and carbon. Therefore, it is sometimes desirable to add small amounts of metals which form thermodynamically stable compounds with impurities such as oxygen or carbon. These metals therefore act as internal agents of appropriation.



   Metals which are suitable for such use are generally those whose oxides or carbides, such as aluminum, thorium, tanthanum, titanium, zirconium and vanadium have very high free forming energies. Usually a quantity is used which

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 slightly exceeds the stohiometric amount required for reaction with oxygen, carbon or other impurities
Slightly larger amounts of these suiting agents can be used if they form alloys in solid solution or intermetallic compounds of high m.p., stable with the bonding metals.

   The amounts used can therefore be between a few tenth% by weight and
10 or even 20% by weight based on the weight of the metal base.



   For example aluminum is a particularly interesting appropriation agent. It forms a very thermodynamically stable and refractory oxide, Al2O3, which is capable, simultaneously, of retaining carbon impurities forming aluminum oxycarbide AlOC and of combining with the binding metals of the invention for forming high melting point refractory alloys and intermetallic compounds. In addition, any excess aluminum which does not combine with the binder metal or with the impurities is vapor distilled off during the manufacture of the refractory dispersions.



   Minor amounts of alloying agents conventionally used with molybdenum, tungsten, chromium and rhenium can also be used in the dispersions as long as they are retained as a homogeneous solution. with metal, which solution has the crystal structure of metal. Amounts of these alloying agents which would form intermetallic compounds or new crystallographic phases should be avoided.

   The permitted percentages of such agents can be determined according to this criterion by consulting the appropriate phase diagrams in standard metallurgical texts., For example, such

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 allowable amounts of conventional agents, such as up to
1% iron in tungsten, up to 30% iron in chromium, small percentages of iron, titanium or zirconium in molybdenum, and even smaller amounts of nickel and cobalt, can be used.



   . The nitrides of aluminum, titanium, tantalum, hafnium, zirconium, niobium or vanadium can be used alone or in combination with each other in the dispersions. When used in combination, it will often be appreciated that interactions of varying degree occur between these nitrides. This may include the formation of solid solutions, the formation of mixed nitride compounds, or combinations thereof. It will be understood that the objects of the invention are achieved both when such interactions take place and when the various nitrides remain in their initial distinct forms.

   With regard to the properties of the dispersions obtained such as wear resistance, mechanical properties, and refractory characteristics, simple mixtures, solid solutions, and mixed nitride compounds all behave in the same way. .



   Other chemically stable refractory compounds such as uranium nitride, boron nitride, beryllium nitride, cerium nitride and thorium nitride can be used to replace part of the titanium nitride, nitride. tantalum, zirconium nitride, hafnium nitride, vanadium nitride, niobium nitride, or aluminum nitride or mixtures thereof.

   Chemically stable refractory carbides, such as titanium carbide, zirconium carbide, tantalum carbide, niobium carbide, and chemically stable refractory oxides such as magnesia, zirconium oxide, alumina and oxide

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 thorium can also be used to replace partial-; also the.nitrides. Some of these refractory borides. more chemically stable, such as titanium or zirconium monoborides, can also be used.



   It is essential, however, that a nitride of titanium, tantalum, zirconium, hafnium, vanadium, niobium, aluminum or their mixtures is always present as one of the non-metallic constituents in the products. dispersions, in amounts of at least 5% by volume of the non-metallic phase of the compositions of the invention, and preferably in amounts greater than 5%. Generally the compositions are improved in proportion to the amount of the essential nitrides which are added, at least to the point where a continuous phase of nitrare is formed in the solid compositions. The criterion necessary to ensure that this is true for most preferred compositions is discussed.



     It is also essential that the refractory compounds used as additives are not of those which react with the bonding metals in such a way as to make them brittle, or which decompose them into elements whose presence cannot be tolerated for the same reason.



   In general, the criterion to be followed in choosing additive compounds is that their melting point exceeds 1600 to 180,000. while their free energies of formation from the constituent elements must be greater than the free energies of the compounds which would be formed by disproportionation of the additive compound and by reaction of the constituent elements with the binder metal.



   For example, Al2O3 is a satisfactory additive when used with tungsten-bonded compositions because its free energy of formation substantially exceeds.

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 combined free energies of the tungsten-aluminum alloy, and of the tungstic oxide which would result from its disproportionation and from the reaction of its constituents with the tungsten. Titanium carbon is a suitable additive for a molybdenum-bonded composition because its free energy of formation exceeds the combined free energies of formation of the titanium-molybdenum alloy and the molybdenum carbon that could result from their formation. disproportionation and reaction with the bonding metal molybdenum.



   Any standard text of reference which provides information on the free energies of formation of metal alloys, intermediate compounds and refractory carbides, nitrides and terminals may be consulted in order to obtain the information necessary for the application of this criterion. .



   It should be noted, however, that small amounts of additives, including those which may react disproportionately, are not absolutely excluded from the compositions of the invention. For example, it would be possible to add a small amount of tungsten carbide to. a tungsten bonded composition of the invention, even though a disproportionate reaction between the bonding tungsten and the tungsten carbide could occur, to form the W2C compound. But when such reactions may occur, it is necessary to restrict the amount of any additive to amounts which are small relative to the amount of the binding metals of the invention in the particular composition. employee.

   Such a restriction prevents the attachment of an amount of binder metal which would reduce the strength of the refractory dispersion and make it undesirably brittle.



   The amount of refractory additive to be used will preferably be; less than an amount sufficient to form an interpenetrating network of the additive and to prevent the formation of a network of essential nitrides.

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   The formation of a continuous network does not depend only on the relative volume fractions of the nitride and the additive, for it is also influenced, to a considerable extent, by the size of the particles or the size. crystallites of nitrides relative to the additive particles. Therefore, if coarse particles of the additive are used, for example particles with a size of 10 microns, together with very finely divided particles of the essential nitrides in question, for example particles of a size between
20 and 100 millimicrons, an interpenetrating network will form, essentially linked by the essential nitrides. This is true - even when nitrides are present in amounts as small as 5% of the non-metallic phase.



   As is generally preferred to use additives having a particle size of less than one micron, larger amounts of essential nitrides, on the order of.
20% of the non-metallic phase is usually required to achieve the desired continuity. Similarly, if the particulate fiber of the essential nitride to be used is greater than 20 millimicrons, it may become necessary to use the nitride in amounts as large as 50% or more of the non-metallic phase to provide the preferred bond. of ni-. trure of the non-metallic continuous phase.



   A general criterion to be followed for the formation of this preferred type of structure is that the product of the volume fraction and the specific surface area of essential nitrides be approximately equal to, or preferably greater than, the product of the volume fraction and of the specific surface of. the additive to be used. By suitably following this criterion in selecting the compositions, the preferred type of structure will usually be obtained.

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   As the fracture is also determined to some extent by the growth rates of the crystals which develop during fabrication, however, it is not necessary to apply this criterion in a completely straightforward fashion. fact rigid, Under particularly favorable circumstances, in which the rate of increase of @ network of nitrides.

   under the conditions of manufacture employed, greatly exceeds the rate of increase or the rate of recrystallization of the additive employed, quantities of essential nitrides considerably lower than those corresponding to the criterion mentioned above can be used and the The preferred interpenetrating network linked by nitrides of the non-metallic phase will still be formed.



   Preparation of metals.



   The metals which can be used in the dispersions of the invention are molybdenum, tungsten, chromium, rhenium, and their alloys. These metals with the requisite degree of purity can be obtained from commercial sources or can be prepared in a conventional manner. A suitable method of preparing these metals to be incorporated in the dispersions is the reduction using hydrogen at low temperature of the corresponding metal oxide.



   In the preparation of molybdenum and tungsten, the oxides of which are somewhat volatile at elevated temperature, it is preferable to employ a two-step reduction. The oxide is first reduced to a lower valent oxide, such as tungsten dioxide or molybdenum dioxide, at a temperature below the melting point of the oxide, for example about 60,000. The reduction is then completed at an elevated temperature of about 900 ° C., for example, which is low enough to avoid excessive agglomeration or sintering of the metal powder.

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   The reduction will be followed by grinding in an inert liquid agent and, if necessary, purification µ using hydrochloric acid. In this way, the pure metal can be obtained in powder form, preferably with a specific surface area greater than 1 m2 / g, which makes it suitable for subsequent mixed dispersion with the aluminum nitride.



   In order to avoid having to purify, it is desirable that the grinding agents used in the grinding be made of the same metal as that which is prepared.



   Preparation of nitrides.



   The nitrides used in the invention can be prepared by any conventional method.



   In a preparation process, a finely ground hydride of titanium, zirconium, tantalum or hafnium or finely divided aluminum, vanadium or niobium metal or a mixture thereof is placed. in a stove with gas, at high temperature. The air is removed from the furnace by purging for about half an hour with an atmosphere such as nitrogen or pure ammonia vapor. The temperature of the furnace is then increased at the rate of about 250 C per hour while maintaining an atmosphere such as nitrogen or ammonia in the furnace. When the temperature is raised from about 700 to 1000 C, the temperature is maintained for a period of time sufficient to be able to complete the formation, at a lower temperature, of the nitride formed.

   This prevents excessive agglomeration of metals formed by the decomposition of hydrides or of the metals themselves if they were used as precursors. The temperature is then raised to about 1100 ° C. and is held there for 1 to 16 hours while a stream of ammonia is maintained through the furnace. The temperature is then raised again to around 1200C,

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 under an atmosphere such as ammonia or nitrogen, and is maintained for a period of 1 to 8 hours.



   The furnace is then cooled to room temperature, and product removed. This three-step heat treatment has been found to eliminate the problems of excessive agglomeration which may occur if the temperature is brought directly to the final temperature of 1200 C, but still allows for the complete virtual conversion of the metal hydride in red corresponding to a lower temperature.



   When the reaction is carried out in these conciliations, it is found that all of these metal nitrides can be prepared in the form of nitride crystals the dimensions of which are colloidal. Although the latter agglomerate, to a certain extent, in clusters, the degree of agglomeration is not enormous and a relatively short grinding cycle in an inert solvent such as oil. hydrocarbon type or acetone is sufficient to break up the aggregates so that only their last crystals are left behind.



   After grinding, it may be desired to purify the nitride by treatment with acid, for example, to remove impurities collected during grinding by attrition of the grinding agent. If it is desired to obtain a very low oxygen level, the nitride can be reduced in an atmosphere such as cracked ammonia, to remove all traces of oxygen collected during the purification process. '
To avoid having to purify, it is preferred to use a grinding agent, such as balls, of the same metal as that with which the nitride is optionally to be dispersed.



   When nitriding aluminum, it is desirable to mix 1 to 25% by volume, based on the aluminum present, of a finely divided material having a high melting point, intimately, with the flakes. aluminum to prevent aluminum

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 to form a molten phase when the temperature exceeds its melting point. Suitable materials for such use are oxides of molybdenum, tungsten, chromium, aluminum, aluminum nitride, and aluminum salts which decompose to aluminum oxide, such as aoetate. aluminum,
In the presence of such high melting point materials, the reaction temperature can be raised to 1200-1500 ° C., to complete the reaction.

   When using molybdenum, tungsten, chromium, a temperature above 1400 0 is recommended to decompose the nitrides of these metals which are. present and to remove residual impurities such as carbon or oxygen which may be present in the metals. However, as high temperatures tend to increase; Due to the particle size of the aluminum nitride that forms, it is preferable to restrict the temperature to 1400 C or above and use high melting point compounds such as aluminum oxide or nitride. .



   During the preparation of the aluminum nitride it is also preferred to maintain a temperature above 900 C. At lower temperatures the reaction requires long periods of time to complete, and the aluminum nitride formed is so reactive in the process. from a chemical point of view that it is difficult to prevent its reaction with the water vapor in the air. However, aluminum nitride formed at somewhat lower temperatures can be used if contact with atmospheric moisture is avoided during handling.



   Preparation of powder dispersions.



   Interdispersions of the metals with nitrides and other refractory compounds if desired in powder form are one of the preferred forms of this invention. Aluminum nitride, titanium nitride, zirconium nitride, tantalum nitride, hafinium nitride, vanadium nitride, niobium nitride or mixtures thereof, and other refractory compounds as desired, can,

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 be mixed or inter-dispersed with the. metal powder in any suitable manner, for example, by mixing in a hydrocarbon solvent or acetone, in a colloid mill or ball mill.



  Grinding periods in a ball mill ranging from 24 to 500 hours have been found to be satisfactory.



   Since the nitride of the invention is difficult to purify, it is desirable to employ grinding agents, such as balls, of the same metal as that with which the nitride; is dispersed. The mill may be one which is coated with an elastomeric material such as neoprene, which is not softened or attacked by the mill fluid.



   After grinding the mixture to homogeneity, the grinding fluid can be removed by washing with a suitable solvent, such as hexane, and drying in vacuo. Chemical analysis can be performed at this point and, if appreciable amounts of oxygen, carbon, or nitrogen are combined with the metal in any form other than the stable refractory compounds mentioned above, the powders can be reduced to remove these impurities. This reduction is preferably carried out below 1000 ° C. with very dry pure hydrogen.



   The average particle size can easily be determined by examining the interdispersed powders using an optical microscope for large particles and an electron microscope for smaller particles.



  In the preferred powder dispersions the area per cm3 of solid material is about 3 to 180 m2. The area per cm3 can be determined by dividing the specific area by the density of the solid material in the dispersion.

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     repair of refractory dispersions.



   Interdispersions of metals with nitrides and other desired refractory compounds in solid form are another preferred form of the invention. A representative process for forming such dispersions is to heat and press the powdered dispersions to near theoretical density, under vacuum or in the presence of an inert atmosphere such as helium nitrogen. , '. hydrogen or argon.



   The pressing temperature depends on the amount of metal used, its state of subdivision and the composition and state of subdivision of the nitride. Generally, temperatures are between 3/10 and 9/10 of the melting point, expressed in degrees Kelvin, of the metallic component and should be at least 1600 C and not higher than 2200 C.



   The greater the amount of nitride used, and the lower the 'pressure' used, the higher the manufacturing temperature should be. '
The time that the compact matter spends at temperature. The highest pressure used and under the full pressure employed will vary with pressing temperature, composition, and state of dispersion. Usually the time varies from a few seconds to 30 minutes or more.



   The pressure employed will also vary depending on the temperature and method of manufacture used and the composition and state of dispersion, but is generally between about 35 to over 420 kilograms per cm 2.



   Usable combinations of pressing conditions will be more fully illustrated in the examples hereinafter.

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Another method of interdispersion of the constituents with each other, prior to the preparation of a solid interdispersion, is to precipitate the metal used on previously prepared fine particles of the niaride used. The metal can be precipitated, for example, as a hydroxide or a hydrous oxide and the resulting homogeneous mixture can then be reduced to hearth in an atmosphere rich in both nitrogen and hydrogen, such as hydrogen. cracked ammonia.

   This allows the reduction of the oxides which are present without making a change in the nitrides used.



   After a refractory dispersion has been prepared, the particle sizes of the constituents can be determined by making a metallographic section, etching the section with an appropriate chemical, and examining the surface with a microscope using an optical microscope. or an electron microscope as appropriate. When using an electron microscope, a conventional carbon or plastic replica is first made from the surface and measurements are then made on the replica.



   The average particle size of the constituents of a refractory disparsion should be less than 50 microns. In the more preferred embodiments the average particle size is less than 10 microns, and in the most preferred embodiments the average particle size is less than one micron.



   The nature of the interdispersion, of the nitride with the metal and the dimensions of the metal in the refractory dispersions are a function of the manufacturing conditions and the volume fraction employed as well as the nature of the starting material.

   Some agglomeration of the nitride particles occurs, but as mentioned above, one of the preferred embodiments is that in which

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 most of the nitride particles are separated from each other by a continuous metallic vehicle giving a homogeneous and uniform dispersion of distinct nitride particles. as previously mentioned, one of the most preferred embodiments is a refractory dispersion in which there is a mixed continuous network or vehicle of distinct very finely divided crystals of the metal phase and the nitride particles. both, such crystallites having an average particle size of less than one micron.



   More particularly, in its preferred aspects, it is desired that the homogeneity of the dispersion be such that the distribution of nitride or metal in the refractory dispersion is distributed on a scale of 100 square microns. By this is meant that a metallographic scan or electron microscopic photographic scan, as is conventionally used in metallurgy to examine the structure of alloys will show both nitride and metal. - tal present within a square area which has no more than 32 microns in side and preferably not more than 10 microns in side.

   Further, in the preferred embodiment, each 10 micron side square which is examined exhibits substantially the same structural characteristics as each other such region in the dispersion within the conventional limits of statistical distribution. . the presence of a continuous phase of the metal in the preferred refractory dispersions can be determined by measuring the electrical resistivity of the dispersion.

   Since the refractory compounds used in this invention have a higher electrical resistance than molybdenum, tungsten, chromium, rhenium or their alloys if the refractory compounds have a distribution such as to break the continuity of the metal, the electrical resistivity of the dispersion

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 refractory will be 10 to 100 times higher than if the metal is continuous. Conversely, if an electrical conductor such as molybdenum, tungsten, chromium or rhenium has a. Distributing in a continuous phase in a refractory dispersion, the electrical resistivity of the dispersion will be inversely proportional to the volume and thickness of the continuous path of the metallic component.

   Appreciable continuity of the metal in a refractory dispersion is indicated by a specific electrical resistivity of less than approx.
 EMI19.1
 At one ohm-centimeter and, in preferred refractory dispersions, the specific electrical resistivity is less than about 0.05 ohm-centimeter. , '
It is usually possible, by inspection of suitably prepared metallographic specimens of the compositions of the invention, to determine and show which of them contains the preferred interpenetrating nitride network.

   If the crystallite size is on the order of one micron or more for the various components of the structure, the existence of such a network can be observed directly in an optical microscope, using a power. 1000 or 2000 times.



   If some structural units, or all structural units, are significantly smaller than one micron, the structure can be examined by electron microscopic replica photographic examination techniques using conventional methods. .



   A technique similar to that used to determine! Undermining the continuity of the metallic phase can be used to determine whether or not the essential nitrides form a continuous vehicle or network. For example, compositions in which tungsten or molybdenum is used as the binder metal and titanium nitride as the essential main nitride can be experimented with in this way.

   There may be, present, other nitrides selected from

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 the essential nitrides mentioned, such as aluminum nitride, as well as suitable additives such as alumina. In these compositions, the tunsgtene is preferably extracted by reacting the composition with a bromine-ethanol solution which does not attack nitrides, oxides and carbides. The electrical conductivity of the partial structure obtained can then be determined.

   Since alumina is a non-conductor, as is aluminum nitride, the presence of appreciable conductivity in such a composition is indicative of a continuous network of titanium nitride, which is. a semiconductor having appreciable electrical conductivity, even at room temperature.



   The refractory dispersions of this invention have a density in excess of 90% of theoretical density and preferably in excess of 95% of theoretical density. These refractory dispersions which are to be used in making cutting tools more preferably have a density in excess of 98% of the theoretical density and are substantially free of pores when examined by metallographic methods. Theoretical density is calculated assuming the specific volumes of individual constituents are added.



   The density of the refractory dispersions can be determined by any technique to determine the simultaneous weight and volume of the compound. Very simply the weight can be determined with a sensitive analytical balance and the volume can be determined by displacement of mercury or water.



   It should be understood that the previously highlighted aspects relating to the structure, purity, density, homogeneity and metal continuity of the refractory dispersions are all factors which contribute to providing these dispersions with improved properties. However the results

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 the most interesting are obtained when all these characteristics are present simultaneously. The most preferred embodiment of the invention is such refractory material in the form of a cutting tool or bit.



   Such a refractory composition is one in which distinct nitride particles and distinct particles of other refractory compounds, if used, having an average size of less than one micron, are homogeneously dispersed in one. A continuous vehicle of molybdenum, tungsten, chromium, rhenium or their alloys such that the uniformity of distribution is on a scale of less than 100 square microns. The average size of the metal crystals in the composition is less than one micron and the continuity of the metal is such that the composition has an electrical resistivity of less than 0.01 ohm-centimeter.

   The amount of nitride and other refractory compounds, if used, is 1 to 19 parts by volume per part of metal, and the density of the composition is in excess of 99% of the theoretical density. The most preferred metals for making such a compound are molybdenum and tungsten. Among the mixtures of preferred refractory compounds, mention may be made of titanium nitride and aluminum nitride, titanium nitride and aluminum oxide; ternary mixtures of aluminum nitride, titanium nitride and aluminum oxide; and mixtures of one, two or all three of those just mentioned with titanium carbide.



   EXAMPLE 1. '
94 grams of particles crushed in a fiber ball mill of 250 millimicrons of titanium hydride are loaded into alumina pods and placed in a furnace purging for 30 minutes with pure nitrogen , after what

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 the furnace atmosphere is replaced with ammonia, and this new atmosphere is maintained throughout subsequent processing. The temperature of the furnace is increased at a rate of 250 C per hour to a temperature of 1000 C and the furnace is maintained at this temperature for 3 hours.



  The temperature is then raised to 1100 C and held for 16 hours, after which it is raised to 1200 C and this temperature is maintained for 6 1/2 hours. The furnace is cooled. to room temperature and a total of 114 g of product is collected as a finely divided powder. This represents 97.8% of the expected yield of a reaction to form titanium nitride. Chemical analysis shows that the product contains 17.91% nitrogen, 0.47% oxygen, the remainder of the composition being titanium.

   The nitrogen surface area of this powder is 0.3 m 2 / g and x-ray examination shows that it consists of titanium nitride with an average caliber of oristallites of 84 millimicrons. No other phase is present.



   50.8 grams of this material are charged to a 1.1 liter capacity rubber coated steel ball mill with 9.45 grams of finely divided metallic tungsten having a particle size of not less than 100 millimicrons and 2500. grams of tungsten carbide elements containing 6% oobalt. The tungsten and cobalt carbide elements are about 6.35mm in diameter and 6.35mm in length and are shaped like small cylinders. Also charged to the mill is 350 cc of a high boiling point hydrocarbon type oil having a flash point of 85 C.

   This crusher was run on rubber coated rollers for a period of 24 hours at a speed of 60 '. turn @ minute. The finely divided powdery dispersion obtained of titanium nitride and metallic tungsten is collected in the mill and separated from the elements of.

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 Tungsten cobalt carbide rod-shaped, separated from most of the oil by decantation, and washed until completely free of oil by six washes with hexane. It is then dried in a vacuum oven.

   Chemical analysis determines, in the final composition, about 18.7 parts by volume of titanium nitride, and about 0.3 part by volume of tungsten carbide, per part by volume of one. metal consisting of 98% by volume of tungsten and 2% by volume of cobalt. Tungsten carbide and cobalt are collected by attrition of the rod-shaped elements during grinding.



   25 grams of this powder are placed in a cylindrical carbon mold, the temperature of the furnace is raised to 1000 ° C. and a pressure of 280 kg / cm2 imposed. The temperature of the furnace is then increased while this pressure is maintained up to a final temperature of 2000 C. and maintained for a period of 5 minutes. The sample is then removed from the furnace. The refractory dispersion obtained according to the invention is cut with a diamond in specimens to test the transverse breaking strength, impact resistance, hardness.
Rockwell and density. A cut is also machined to form an insert of a metal cutting tool.

   The transverse breaking strength is 3390 kg / cm2, its impact resistance about 6.66 kg / cm2, its Rockwall A hardness of 90.5. The density is 6.11 g / cm3, which is 97.8% of the density of 6.25 g / cm3 which would be expected for this composition.



   This composition forms an excellent cutting tool on 4340 steel, even at a surface speed of 450 meters per minute.



   EXAMPLE 2.



   40.2 grams of the titanium nitride powder of Example 1 and 47.7 grams of a metallic tungsten powder with a size of 100 millimicrons are placed in a ball mill, with the same quantity of 'elements of tungsten carbide and

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 cobalt and oil of the hydrocarbon type as in Example 1. ' Grinding is carried out in a similar fashion, as is the recovery of the final product. The intimate dispersion obtained according to the invention contains, according to the chemical analysis carried out, approximately 3.0 parts by volume of titanium nitride and approximately 0.05 part by volume of tunbsten carbide per part by volume of. a metal consisting of 99.6% by volume of tungsten and 0.4% by volume of cobalt.



   33 grams of this powder are placed in a carbon cylinder and pressed in the installation described in Example 1, under the same pressing conditions. The refractory dispersion obtained of the invention has a tensile strength. transverse of 5810 kg / om2, an impact resistance of about 10.29 kg / cm2, and a Rockwell A hardness of 88.3. The density is 8.79 g / om3; which represents 98% of the theoretical density of 8.97 g / cm3 expected for this composition.



   Metallographic examination of the refractory composition shows an interdispersion of titanium nitride and tungsten carbide in a tungsten-cobalt alloy. The average particle size of the alloy crystals is between 0.4 and 0.8 microns and the average particle size of titanium nitride is about 0.5 microns.



   Metallographic examination of the dispersion also shows that the tungsten-cobalt alloy and the titanium nitride are both present in a square of 10 microns side and 1Q. The 100 square micron regions examined, nine showed these same structural features. ,
The electrical resistivity of the dispersion is about 0.01 ohm-centimeter. This low value of electrical resistivity indicates that the continuity of the metal in this refractory dispersion is not interrupted by titanium nitride.

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   A cutting tool insert made from this composition is tested on 4340 steel, using a depth of cut of 1.5875 mm and varying the surface speed at which the cut is made.



  At a surface speed of 150 meters per minute, after 3 minutes of cutting, the wear of the cutting edge is approximately 0.152 mm, the depth of the crater formed 6.35 microns and the width of the crater 0.5588. mm. At surface speed. t 300 meters per minute, after an experiment of 1 minute, the wear of the bit is 0.127 mm, the depth of the crater is 12.7 microns and its width is 0.6604 mm.



  Even at a surface speed of 450 meters per minute, bit wear after one minute of cutting is between 0.1524 mm and 0.381 mm for various different faces of the tool insert. , while the crater width is 0.4064 mm and the crater depth is 50.8 microns.



    EXAMPLE 3 .. -
93.2 grams of zirconium hydride ground in a ball mill are placed in alumina boats and placed in a cold alumina tube. The tube is swept with. ammonia plus nitrogen. While maintaining a current of ammonia, the tube is heated to 1000 ° C. over 3 hours. It is maintained at 1000 C for three hours and the temperature is then raised to 1100 C and maintained at this value for 16 hours. Finally, it is heated to 1200 C and held for 8 hours, cooled to 250. C, removed from the hot zone of the nitrogen furnace and cooled to room temperature.



   . Chemical analysis of this material gives 11.28% nitrogen, 0.27% oxygen and 88.2% zirconium.

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   X-ray examination shows this material to consist of zirconium nitride having a crystallite size of 160 mm as indicated by the broadening of the lines.



   67.4 grams of this zirconium nitride powder and 9.6 grams of a finely divided metallic tungsten powder are ground during. 24 hours in a 1.1 liter rubber covered steel ball mill filled to 40% of its volume with cylindrical tungsten carbon rods containing 6% cobalt, 6.35 mm in diameter and 6.35 mm long. The grinder also contains
350 cm3 of a high boiling point hydrocarbon type oil. The grinding speed is 60 revolutions per minute. The recovery of the mixed powders of metallic tungsten and of zirconium nitride is carried out as described in the preceding examples.

   This powdered dispersion is hot pressed under the conditions described in Examples 1 and 2 and the refractory dispersion obtained according to the invention is analyzed. It contains approximately 19 parts by volume of zirconium nitride per part by volume of tungsten and at a density of 7.37 g / cm3 which represents 96% of the theoretical density which is expected for this composition, Its hardness Rockwell A is 87.8, its impact strength is 3.016 kg / cm2, and its transverse breaking strength is 3640 kg / cm2.



   This refractory material is shaped into a cutting tool insert and used as a cutting tool on 4340 steel. N using a cutting depth of 1.5875 mm and varying the cutting speed, it is observed that at a cutting speed of 152 surface meters per minute, using a cutting time of 3 minutes, the bit wear is 0.1651 mm, the crater width is 0.508 mm and the depth of the crater is

  <Desc / Clms Page number 27>

 20.32 microns. At a cutting speed of 304 surface meters per minute after one minute of cutting, the wear of the cutting or cutting edge is 0.127 mm, the crater width of.



  0.508 mm and the depth of the crater is 12.7 microns.



  Even at speeds of 456 surface meters per minute, after one minute of cutting, the bit wear is still only 0.889 mm, the crater width is 0.762 mm, and the crater depth is 88.9 microns.



   EXAMPLE 4.



   52.2 grams of the zirconium nitride of Example 3 and 48.3 g of a finely divided metallic tungsten powder are ground using the equipment and conditions described in Example 3.



   40 grams of this are pressed, using the conditions mentioned in Examples 1 to 3, and the refractory dispersion obtained according to the invention consists of 3 parts by volume of zirconium nitride per part by volume of tungsten. Resistance to. rupture of this refractory material is 5355 kg / cm2, its impact resistance is 6.864 kg-meter / cm2, and its Rockwell A hardness is 85.9.



   Its density is equal to 9.73 g / cm3, which corresponds to 96% of the theoretical density, which is 10.15 g / cm3, which one could: - hope for this composition.



   This refractory material is tested in the form of an insert of a cutting tool on 4340 steel under the conditions described in the previous example. At a cutting speed of 152 meters in surface per minute, the wear of the cutting edge is found to be 0.2032 mm, the crater width is 0.5588 mm and the crater depth is 25.4 microns. after 3 minutes of cutting. At a surface speed of
304 meters / minute, bit wear is 0.2032mm, crater width is 0.5334mm, and crater depth is 25.4 microns.

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   EXAMPLE 5.



   68.4 grams of the zirconium nitride of Example 3 and 1.77 grams of pure metallic chromium with a particle size of -0.44 mm are ground in a steel ball mill lined with rubber of a size. capacity of 1.1 liters, filled to 40% of its capacity with balls or steel balls with a diameter of 4; 732 mm and containing 350 om3 of a hydrocarbon-type oil. high boiling point bure. Grinding is carried out at a speed of 60 revolutions per minute and continued for 14 hours. The finely divided powder collected 0.86 grams of iron by attrition of the steel balls of the mill. This powder is recovered and purified as described in the previous examples.

   Chemical analysis shows that it contains 96.4% by volume of zirconium nitride, 2.5% by volume of metallic chromium and 1.1% by volume of iron. Thus the composition of this refractory material is 26.8 parts by volume of zirconium nitride per part by volume of an alloy consisting of 70% by weight of chromium and 30% by weight of iron.



   28 grams of this material are pressed under a pressure of 280 kg / cm2 imposed initially at a temperature of 1000 C, maintained under this pressure, while the temperature is raised to 1700 C, maintained at this temperature during 5 minutes, cooled and removed from the press. The refractory dispersion obtained according to the invention has a transverse breaking strength of 7521.5 kg / cm2, an impact resistance of 5.824 kg-meter / cm2, a Rockwell A hardness of 87.8 and a density of 6.74 g / cm3, which represents 96% of the theoretical density of 7.10 grams / cm3 which could be expected for this composition.

   This material makes a good cutting tool at a surface speed of 152 meters / minute on 4340 steel using a depth of cut of

  <Desc / Clms Page number 29>

 1.587 mm. After 3 minutes of cutting under these conditions, the wear of the bit is 0.381 mm, the crater width of: 0.508 mm and the crater depth of 6.35 microns. ',
This material is also an exceptional construction material at high temperatures, because it has excellent resistance to oxidation at temperatures up to and including 1100 C, while maintaining a a substantial fraction of its tensile strength at room temperature, even at elevated temperatures.



   EXAMPLE 6.



   679.5 grams of metallic tungsten powder are placed in a steel ball mill with a capacity of 3.78 liters filled up to 40% of its volume with 4.762 mm steel balls. This substance is covered with 1700 cm3 of a high boiling point hydrocarbon having a flash point of 170 C, and crushed for a period of 3 days at a speed of 60 rpm. The metallic tungsten powder is separated by sedimentation and centrifugation from the oil and washed twice with hexane, then with acetone, and finally with water. It is treated with a mixture of 1 liter of concentrated hydrochloric acid and 1.5 liters of distilled water, and heated for one hour at 90 C.

   This is done to dissolve the iron collected during grinding. It is allowed to stay, while stirring with the hydrochloric acid-water mixture, the whole night. It is then centrifuged to recover the tungsten and to separate it from the dissolved iron which has been removed by the acid treatment and washed with normal 0.1 HCl solution until the iron is removed.



   This requires 5 washes. It is then washed again with

  <Desc / Clms Page number 30>

 distilled water until the chloride ions are removed, and dried in a vacuum oven. The tungsten powder thus obtained has a nitrogenous surface area of 3.0 m2 / g, which corresponds to an individual particle size of about 100 milligrams. Chemical analysis gives 98.91% metal tungsten. lic, q, 6% iron and 0.66% oxygen.



   77.2 grams of the finely divided metallic tungsten is mixed with 32.6 grams of the titanium nitride of Example 1, and the mixture is ground over a period of 3 days in a rubber-lined ball mill. A capacity of 1.1 liters filled to 40% of its volume with 6.35 mm alumina balls and containing 350 cm3 of a high boiling point hydrocarbon type oil. The recovery of the powder consisting of tungsten, and of titanium nitride in the form of a dispersion, from the mill and its separation from the oil of the hydrocarbon type are carried out as described in the preceding example.



   44 grams of this dispersion are pressed at a temperature of 22000C, using a hold time of 1 minute and a pressure of .280 kg / cm2. The refractory dispersion obtained according to the invention contains 1.5 parts by volume of titanium nitride per part by volume of tungsten and has a transverse breaking strength of 7420 kg / cm2, an impact strength of 11.856 kg-meter / cm2 and a Rockwell hardness
A of 87.5. Its density is 10.93 g / cm3, which represents 99.6% of the theoretical density which is expected for this composition.



   This refractory dispersion makes an excellent cutting tool on steel, even at speeds of 304 surface meters per minute and this dispersion is also a good cutting tool on cast iron, due to its strength. high impact, low wear, and low tendency to form craters,.

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    EXAMPLE 7.



   77.2 grams of the metallic tungsten prepared as described in Example 6 are charged to a mill with 36 grams of zirconium nitride prepared as described in Example 3; The grinding and the recovery of the ground oil powders are carried out as described in the previous example. 45 gr @ m- mes of the intimately obtained mixed powder dispersion of tungsten and. of zirconium nitride are pressed at a temperature of 2100 C with a hold time of -3 minutes using a pressure of 420 kg / cm2.

   The refractory dispersion obtained has a tensile strength of 7000 kg / cm2, an impact strength of 9.672 kgrm / cm2, a Rockwell A hardness of 86.5 and. a density of 10.79 g / cm3, which represents 95.3% of the theoretical density for this composition. This refractory dispersion consists of 1.5 parts by volume of zirconium nitride / part by volume of metallic tungsten. This refractory material makes an excellent cutting tool at cutting speeds of up to 152 surface meters / minute on cast iron, its high impact resistance and high thermal conductivity making it attractive even when cutting. interrupted.



   EXAMPLE 8.



   1360 grams of molybdenum metal powder with a particle size of -0.044 millimeter are placed in a steel ball mill with a capacity of 3.78 liters filled to 40% of its volume with steel balls and also containing,
1800 cc of a high boiling point hydrocarbon type oil. This substance is crushed at a speed of 60 rpm for 3 days, after which the molybdenum powder is separated from the hydrocarbon type oil and steel balls, washed completely with hexane to remove the oil.

  <Desc / Clms Page number 32>

 and dried in a vacuum oven. It is purified using a treatment (hydrochloric acid and water in a manner identical to that described for the purification of the metal tungsten powder of Example 6.

   The finely divided metallic molybdenum powder obtained has an average particle size of 100 to 200 millimicrons and contains only traces of iron as an impurity.



   42.2 grams of the titanium nitride of Example 1 are placed in a mill with 7.15 grams of the metallic molybdenum powder prepared as described in the example above. The crusher has a capacity of 1.1 liters; it is of steel lined with rubber and contains 350 cc of a high boiling point hydrocarbon type oil; it is filled with 2600 grams of rod-shaped elements made of tungsten carbide containing 6% cobalt. The mill is started for 24 hours at 60 revolutions per minute, after which the intimate mixture consisting of the metal powder and the titanium nitride is recovered, as described in the preceding examples'.



   20 grams of the resulting dispersion, which consists of 13.3 parts by volume of titanium nitride per part by volume of molybdenum, are hot pressed at a maximum temperature of 2100 under a pressure of 402 kg / cm2 and kept under these conditions for 15 minutes before cooling and removing it from the press. The refraction dispersion. silencer obtained according to the invention has a transverse breaking strength of 4690 kg / cm2, a Rockwell A hardness of
89.30 and an impact resistance of 8.112 kg-meter / cm2. Its density is 4.88 grams / cm3, which represents 99% of its theoretical density calculated for this composition.

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    EXAMPLE 9.



   42.54 grams of the zirconium nitride of Example 3 and 40.8 grams of the finely divided molybdenum metal of Example 8, together with 0.2 gram of titanium hydride are ground under the conditions. described in the previous example. 24 grams of this powdered dispersion are hot pressed at a maximum temperature of 2000 ° C., using a pressure of 280 kg / cm2 with a hold time of 5 minutes under these conditions.



   The refractory dispersion obtained consists of 1.5 part by volume of zirconium nitride per part by volume of a molybdenum alloy containing 0.5% by weight of titanium. The transverse breaking strength of this refractory material is 5950 kg / cm2, its impact resistance is 15.6 kg-meter / cm2 and its Rockwell A hardness is 83.0. Its density is 6.33 g / cm3, which substantially represents the theoretical density expected for this composition.



   EXAMPLE 10.



   30.7 grams of the titanium nitride of Example 1 are charged to a mill with 25.5 grams of the colloidal metal powder prepared as described in Example 8.



   0.55 g of zirconium hydride is also added. The grinding is carried out in a steel ball mill filled with rubber with a capacity of 1.1 liters filled to 40% of its volume with sticks of pure metallic molybdenum having
6.35mm in diameter by 6.35mm in length. The grinding is constituted for a period of 48 hours at 60 revolutions per minute with regard to the speed of the grinder.



   The recovery and purification of the hydrocarbon-type oil powder contained therein is carried out as in the previous examples.

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   40 grams of this powdered dispersion are pressed at a temperature of 2200 C using a pressure of 280 kg / cm2 with a holding time under these conditions of one minute. The dense body obtained according to the invention is cooled and cut into specimens to test its mechanical properties. A chemical analysis shows that this body contains 3 parts by volume of titanium nitride per part by volume of a metal alloy consisting of
98% by weight of molybdenum and 2% by weight of zirconium.



   The transverse breaking strength of this refractory material is 8680 kg / cm2, its impact strength is 12.48 kg-meter / cm2 and its Rockwell A hardness is 84. Its density is 6.62 grams / cm2. cm3, which represents 100% of the theoretical density calculated for this composition.



     EXAMPLE 11.



   53.2 grams of the zirconium nitride of the example
3 and 17.75 grams of pure chromium metal powder with a caliber of 10 microns are loaded into a crusher, together with rod-shaped grinding elements made of molybdenum and 350 cm3 of hydro-type oil. - high boiling point carbide, and ground as described in the previous example. The recovery is also carried out as described in the previous examples.



   28 grams of this powdered dispersion are pressed at a temperature of 1850 C, under a pressure of 35 kg / cm2, with a holding time of 30 minutes. The refractory dispersion obtained which consists of 3 parts by volume of zirconium nitride per part by volume of metallic chromium, at a density of 6.85 grams / cm3, which represents 96.5% of the theoretical density provided for this composition . Its transverse breaking strength is 9100 kg / cm2

  <Desc / Clms Page number 35>

 t its impact resistance is 16.64 kg-meter / cm2 and its Rockwell hardness. A is 83.

   This refractory material is useful as a high temperature building material; shows good resistance to oxidation and also good strength even at temperatures over 1000 C ..



   EXAMPLE 12. '
An alloy of titanium and tantalum in the weight ratio of 90 parts titanium to 10 parts tantalum is hydrided at a temperature of 800 C under an atmosphere of pure hydrogen and slowly cooled in the furnace while the temperature is maintained. hydrogen atmosphere. This composition is then ground in a ball mill to provide a finely divided mixed hydride containing titanium and tantalum in the weight ratio of 90 to 10.



   This composition is now nitrided, using the methods and conditions described in Example 1, to produce a finely divided powder of titanium and tantalum nitrides in the 90/10 weight ratio.



   47.5 grams of this powder, 26.0 grams of the tungsten powder of Example 6 and 1.07 grams of a pure metallic chromium powder with a particle size of less than 10 microns are charged. in a rubber lined steel ball mill with a capacity of 1.1 liters, together with 350 cc of a high boiling point hydrocarbon type oil. The mill is also filled to 40% of its volume with sticks with a diameter of 6.35 mm and a length of 6.35 mm made of pure metallic tungsten.



   This composition is ground for 48 hours and recovered as described in the previous examples. 33 grams of the powdered dispersion are pressed at a temperature of 1975 C

  <Desc / Clms Page number 36>

 using a pressure of 420 kg / cm2, with a hold time of 30 minutes, '
The resulting refractory dispersion consists of about 5.1 parts by volume of titanium nitride and about 0.6 parts by volume of tantalum nitride per part by volume of a tungsten-chromium alloy in a ratio volume of 90/10
The tensile strength of this refractory material is 5740 kg / cm2, its impact strength is 8.32 kg-meter / cm2 and its density is 7.46 grams / cm3, which represents substantially 100% of the theoretical density provided for this composition.



   EXAMPLE 13.



   29.5 gwammes of the titanium nitride of Example 1,.



   12.3 grams of titanium carbide powder of a particle size of about 5 microns, 15.3 grams of the metallic molybdenum powder of Example 8 and 10.65 grams of pure chromium powder of a size particulate less than
10 microns are ground in a steel ball mill lined with rubber with a capacity of 1.1 liters filled to 40% of its volume with molybdenum sticks with a diameter and a length of 6, 35 mm and 350 cm3 of an oil, of the high-boiling point hydrocarbon type. The grinding is carried out for 48 hours at a speed of 60 revolutions per minute.



   The powder dispersion is recovered as in the previous examples, 28 grams of this powdered dispersion is hot pressed at a temperature. of 2000 C under a session of 280 kg / cm2, with a holding time of 5 minutes. The refractory dispersion

  <Desc / Clms Page number 37>

 obtained consists of approximately 1.75 part by volume of titanium nitride and approximately 0.58 part by volume of titanium carbide per part by volume of metal.



   After hot pressing, an x-ray examination; shows that the metallic constituents are present in the form of a molybdenum-chromium alloy. The tensile strength of this refractory material is 6475 kg / cm2, its impact resistance is 11.024 kg-meter / cm2 and its Rockwell A hardness is 85. The density of this composition is 6.78 grams / cm2. cm3, which represents 99% of the theoretical density calculated for this composition.



  EXAMPLE 14.



   193 grams of the metallic tungsten powder of Example 6 and 153 grams of the metallic molybdenum powder of Example 8 are thoroughly mixed and melted to produce an alloy consisting of 40% by volume of tungsten and 60% by volume of molybdenum. The obtained material is crushed in a jaw crusher to reduce it to a powder and is then crushed and purified as described in Examples 6 and 8 to prepare a fine powder of tungsten and molybdenum, respectively.



     36.5 grams of the titanium nitride of Example 1 is mixed with 3.2 grams of rutile-type titanium dioxide having a particle size of about 1 micron, and
33.4 grams of the finely divided powdered alloy of molybdenum and tungsten. All of these substances are ground as described in the previous example using tungsten sticks as grinding agents. -
The recovery of the intemixed powder dispersion is also carried out as described in the previous examples.

  <Desc / Clms Page number 38>

 



   35 grams of this powdered dispersion are pressed), a temperature of 20000C under a pressure of 280 kg / cm2, using a holding time of 15 minutes.



   The refractory dispersion obtained according to the invention contains 2.7 parts by volume of titanium nitride and 0.3 part by volume of titanium dioxide per part by volume of a metal alloy of tungsten and molybdenum. in a volume ratio of 40/60. The transverse breaking strength of this refractory material is 7000 kg / cm2, its impact strength is 13.52 kg-m / cm2 and its Rockwell A hardness is 87.3. Its density is 8.40 grams / cm3, which represents 99.7% of the theoretical density expected for this composition.



   EXAMPLE 15.



   95 grams of the zirconium nitride powder of Example 3 and 5 grams of a finely divided powder of hafnium nitride are mixed thoroughly and agglomerated or sintered for 5 hours at a temperature of 1750 C, these substances being contained in alumina pods.



  The agglomerated powder obtained is ground to obtain particles of about 50 microns in diameter, and 64.8 grams of this powder are ground with 7.1 grams of pure metallic chromium powder with a particle size of 10. microns, using rod-shaped elements made of tungsten, a grinding time of 48 hours, 350 cc of a high boiling point hydrocarbon type oil as a dispersing agent and a speed of 60 revolutions per minute.

  <Desc / Clms Page number 39>

 



   The recovery is carried out as described in the previous examples and 30 grams of this powder is pressed hot at a temperature of 1700 ° C. under a pressure of 420 kg / cm 2 with a holding time of 30 minutes,
The refractory dispersion obtained consists of 8.55 parts by volume of zirconium nitride and 0.45 parts by volume of hafnium nitride per part by volume of chromium.



   The transverse breaking strength of this refractory material is 8050 kg / cm2, its impact strength is 10.4 kg-meter / cm2 and its Rockwell hardness. A is 86.0. Its density is 7.19 grams / cm3, which corresponds approximately to the theoretical density expected for this composition.
EXAMPLE 16.



   20.2 grams of the metallic tungsten powder of Example 6, 8.5 grams of the metallic rhenium powder of a particle size of 10 microns, 41.6 grams of the titanium nitride powder of the Example 1 and 6 O grams of the zirconium nitride powder of Example 3 are ground, using rod-shaped elements made from tungsten, with the other conditions for grinding and recovery. of the powder dispersion used in the previous example.



   After recovery of the powder and its purification, 35 grams are hot pressed at a temperature of 2100 C, a pressure of 420 kg / cm2 and a hold time of 1 minute. The resulting refractory dispersion consists of 5.1 parts by volume of titanium nitride and 0.57 parts by volume of zirconium nitride per part by volume, of a metal consisting of tungsten and rhenium 'in the ratio. - volume port of 70 parts of tungsten to 30 parts of rhenium.

  <Desc / Clms Page number 40>

 



   This composition is then agglomerated or sintered. at a temperature of 2100 C for a period of 24 hours to complete the alloy of the tungsten and rhenium phases.



   After this treatment, the mechanical properties and density of its substance are determined. It 'turns out that. the transverse breaking strength is 7490 kg / cm2, its impact resistance is 31.20 kg-meter / cm2 and its hardness
Rockwell A of 90.0. The density is 6.33 grams / cm3 which represents 97% of the theoretical density expected for this composition.



   EXAMPLE 17.



   38 grams of the titanium nitride of Example 1, 18.4 grams of the metallic molybdenum powder of Example 8 and
25; 2 grams of metallic rhenium powder of a caliber
10 microns are ground using shaped elements,.



  . rods made of molybdenum under the conditions described for the two preceding examples. The recovery is ef-. also performed as in the previous examples.



   32 grams of the finely divided powdered dispersion obtained are pressed at a temperature of 2000 ° C. under a pressure of 28D kg / cm 2 with a holding time of 5 minutes. This sample is then annealed under vacuum at 2000 C. for a period of 24 hours to complete the alloy by diffusion of molybdenum and rhenium. The refractory dispersion .., re obtained contains approximately 2.33 parts by volume of titanium nitride per part by volume of an alloy consisting of 60% by volume of molybdenum and 40% by volume of rhenium.

   Its transverse breaking strength is .6300 kg / cm2, its impact resistance is 26 kg-meter / cm2 and its hardness
Rockwell A is 89.0 Its density is 8.16 grams / cm3 which is approximately the theoretical density expected for this composition.

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   EXAMPLE 18.



   30.4 grams of the titanium nitride of Example 1,
58.6 grams of the metallic tungsten powder of Example 6 and 7.8 grams of an aluminum nitride powder with a size smaller than 10 microns are ground using elements in the form of rods of tungsten, under the grinding conditions described in Example 15. The recovery is carried out as described previously and 36 grams of this composition are pressed at a temperature of 2200 C under a pressure of 280 kg / cm2 with a time of hold for 10 minutes. The refractory dispersion obtained contains 2.8 parts by volume of titanium nitride and 1.2 parts by volume of aluminum nitride per part by volume of metallic tungsten.



   The transverse breaking strength of this refractory substance is 6720 kg / cm2, its impact resistance is 7.8 kg-meter / cm2, its Rockwell A hardness is
90.5 and its density is 9.68 grams / cm3, which corresponds to 100% of the theoretical density expected for this composition.



    EXAMPLE 19.



   407.2 grams of the titanium nitride (from Example 1 and 19.2 grams of a tungsten metal powder with a particle size of 100 millimicrons are ground.
500 hours in a steel ball mill with a capacity of 7.56 liters filled to 40% of its volume with metallic tungsten sticks and containing a high boiling point hydrocarbon type oil in sufficient quantities to barely cover the sticks with metallic tungsten and finely divided mixed powders.

  <Desc / Clms Page number 42>

 



   Recovery is performed as described in. the preceding examples and the mixture obtained of titanium nitride and metallic tungsten is hot pressed at a temperature of 21000C under a pressure of 280 kg / cm2, maintained at this pressure for 5 minutes, cooled and removed from the press. This refractory material consists of a dispersion of 75 parts by volume of titanium nitride in 1 part by volume of metallic tungsten. The density of this composition is 5.69 grams / cm3. This refractory material makes an excellent cutting tool, especially for making high speed cuts with. relatively light feeds on steel or cast iron.



   EXAMPLE 20.



     537.6 grams of the titanium nitride of Example 1 and 10.2 grams of the metallic molybdenum powder of Example 8 are ground as described in the previous example.



   Crusher recovery, purification, drying and hot pressing are also performed as described in the previous example.



   The refractory material obtained consists of a dispersion of 99 parts by volume of titanium nitride and
1.part by volume of metallic molybdenum. The density of this composition is 5.48 grams / cm3, which corresponds to the theoretical density expected for this composition. As in the previous example, this refractory material makes an excellent cutting tool for light, high speed cuts on steels and cast iron.

  <Desc / Clms Page number 43>

 



   EXAMPLE 21.



     40 grams of a finely divided form of gamma alumina, having an area of about 200 m2 / gram and consisting of relatively unagglomerated spheres are mixed with 400 grams of a pigment in the form of aluminum rods having an oxygen content by 1.43%. To this mixture is added 5.5 grams of a dispersion of metallic lithium in paraffin wax, the content of metallic lithium being about 37%. These substances are loaded into a steel grinder with a capacity of 3.78 liters which is filled to 40% of its volume with steel balls.

   A sufficient amount of an isoparaffinic hydrocarbon solvent having a flash point of 85 ° C. is then added to this mixture to coat the steel balls. The load of steel balls weighed 9288 grams and 1700 cc of a high boiling point hydrocarbon type oil was used. The mill is closed and rotated on rollers rotating at a speed of 60 rpm for a period of 4 days. A sample of about 150 grams of this material is separated from the steel balls and the hydrocarbon solvent and. loaded in a carbon boat which is placed in an alumina tube-which, in turn, is placed in an oven. 'electric.

   The temperature was raised to 1450 C while maintaining an atmosphere of cracked ammonia and N2 in the tube for about 3 hours, and maintained at this value for 2 hours.



   The product at this time consists of a powder. very finely divided aluminum nitride having an area of 6.6 m2 / gram and a crystallite size of 210 millimicrons as established by the broadening of the x-ray lines.

  <Desc / Clms Page number 44>

 



   'After determining the specific surface, this material is placed back in the carbon boat and burnt for an additional 8 hours under a nitrogen atmosphere at 1450 ° C. A chemical analysis shows that this material contains 65% aluminum, 2.43% oxygen and 30.72% nitrogen.



   Its surface is 2.0 m2 / gram. X-ray line broadening measurements show this material to be aluminum nitride having a dice size of about 265 millimicrons.



   20 grams of this aluminum nitride are mixed in a high speed mixer, suspended in 200.cm2 of the same high boiling point hydroqarbon type solvent that was used in grinding, with
3 grams of metallic molybdenum powder of a caliber less than 0.044 mm. The mixture of aluminum nitride and metal molybone is separated from the solvent by sedimentation, washed 4 times with hexane and dried overnight in a vacuum oven.



   10 grams of this powder, which consists of about 20.9 parts by volume of aluminum nitride per part by volume of molybdenum, are pressed in a hot press using carbon molds with a diameter. 2.54 cm.



   At a temperature of 160,000, a pressure of 14 kg / cm2 is applied to the sample, then the temperature is increased to 1900 C, after which Impression is increased to 280 kg / cm2, the temperature is increased again up to 2000 C and the sample is kept at this temperature for 5 minutes. The mold is cooled and the sample removed.



   A metallographic examination of the product obtained shows an interdispersion of metallic molybdenum of a size between 1 and 5 microns, with particles of an average size of 4 microns of the aluminum nitride of the invention. -   The

  <Desc / Clms Page number 45>

 Molybdenum metal is introduced in the form of crystals with a particle size of about 40 microns initially, and the grinding is not considerable. The electrical resistivity of the dispersion is 3.07 x 105 ohm / cm. This very high electrical resistivity value shows that the continuity of molybdenum in this dispersion is interrupted by aluminum nitride.

   Notwithstanding this fact, it should be noted that the use of this dispersion as a cutting tool on steel is still quite remarkable, as will be discussed in the following part of the example.



     The molded product is cut into small samples to test for transverse fracture, into bars to test impact resistance, and a cut section to evaluate sharp tips for cutting steel. The density of the dispersion was found to be 353 grams / cm3, which represented 98.7% of the theoretical density. The impact strength is 5.304 kg-meter / cm2, its Rockwell A hardness is 89.2, and the average transverse tensile strength of two stiffened bars is 3370.5 kg / cm2.



   The dispersion is tested as a cutting tool for steel on 4340 steel at feed rates of 103, 152, 304 and 456 surface meters per minute. The depth of the cut is 1.587 mm. The dispersion is very satisfactory, showing wear of the cutting edge at 103 surface meters per minute of only 0.127 mm after 3 minutes of cutting, from 0.2286 mm at 152 surface meters per minute after 3 minutes of cutting , and an edge wear of 0.2032 mm after 1 minute of cutting at 304 surface meters per minute.

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   EXAMPLE 22.



   20 grams of the aluminum nitride prepared as described in Example 21 are dispersed with each other with 5.6 grams of a -0.044 mm caliber tungsten metallic powder, mixed, washed, dried and pressed as described. in example 21.



  The dispersion obtained consists of approximately 21.5 parts by volume of aluminum nitride per part by volume of metallic tungsten, which corresponds to 1% by volume of 4.45% of metallic tungsten. After pressing, this dispersion has a resistance. impact of 4.16 kt-meter / cm2, a density of 3.93 grams / cm3 and an average tensile strength, based on the 4 bar tests, of 3052 kg / cm2. The density is 99.82% of the theoretical density of this dispersion. Rockwell A hardness is 89.9.



   This sample is examined by a metallographic technique and is found to consist of interdispersion of metallic tungsten having an average particle size of 1 to 6 microns and aluminum nitride having an average particle size. less than 4 microns. X-ray examination shows that the phases present are aluminum nitride, metallic tungsten and a small amount of tungsten carbide (W2C). Electrical resistivity is 4.0 x 105 ohm-cm. This high electrical resistivity is characteristic of a discontinuous phase of metallic tungsten.

   Despite this fact, as noted below, this dispersion still provides a satisfactory cutting tool for cutting steel.



   The dispersion is tested as a cutting tool similar to that of Example 21. It shows 0.127 mm edge wear after 3 minutes of cutting at a speed of 103 meters. on surface per minute on 4340 steel, and 0.254 mm apugs a cut for 30 seconds

  <Desc / Clms Page number 47>

      at a surface speed of 304 meters / minute; even after cutting for a full minute at a surface speed of
304 meters / minute, this dispersion shows a wear of the cutting edge which is only 0.3048 mm to only 0.406 mm.



   EXAMPLE 23.



   679 grams of a metallic tungsten powder are placed in a steel ball mill with a capacity of 3; 78 liters filled to 40% of its volume with balls or steel balls of a diameter of 4.762 mm. All the powder and the balls are covered. of 1700 cc of a high boiling hydrocarbon having a flash point of 85 ° C., and ground for a period of 3 days at a speed of 60 rpm. The metallic tungsten powder is separated by sedimentation and centrifugation from the oil and washed twice with hexane, then with aceto and. finally with water.

   It is treated with a mixture of 1 liter of concentrated hydrochloric acid and 1.5 liters of distilled water, and heated for 1 hour at 90 C. This operation is carried out to dissolve the iron collected during the heating. grinding. This substance is left to stand while stirring with the mixture of hydrochloric acid and water until the next day. It is then subjected to centrifugation to recover the tungsten and to separate it from the dissolved iron which has been removed by the acid treatment and wash it with 0.1 normal hydrochloric acid solution. until it is iron-free. This requires 5 washes.

   The substance is then washed further with distilled water until it is free from chloride ions, and dried in a vacuum oven: The tungsten powder thus obtained has a nitrogen surface area of 3.0. m2 / gram, which corresponds to an individual particle size of about 100 millimicrons.

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   Chemical analysis shows that this material consists of approximately 98.9% metallic tungsten, 0.6% iron and 0.7% oxygen. 66 grams of this tungsten powder are ground in a ball mill lined with rubber stroke.
34 g of aluminum nitride prepared as described in example
21. The mill is filled with alumina balls or beads, approximately 6.35 mm in diameter, which occupy 40% of the volume, of the mill. This mill also contains 350 cc of a high boiling point hydrocarbon, having a flash point of 85 C.

   After grinding overnight at 60 rpm, the product is recovered by filtering, washing with hexane and drying in a vacuum oven. A sample of
25 grams is pressed under the same conditions as those in Examples 21 and. 22 and the resulting dispersion is analyzed in a similar fashion. It has an impact strength of 5.512 kg-m / cm2, a Rockwell A hardness of 90.1, an average transverse tensile strength of 6742.75 kg / cm2 and a density of 6.98 grams / cm3. Compared to a theoretical density of
7.26 g / cm3 expected for a composition of this type, this represents 96.14% of the theoretical density. The dispersion is composed of about 2.94 parts by volume of aluminum nitride per part by volume of metal.



     When experimenting on 4340 steel as described in Example 21 as a cutting tool, the scattering shows cutting edge or cutting edge wear of 0.127 mm, a total width of crater of 0.635 mm and a crater depth of 0.0635 mm after 3 minutes of cutting at a surface speed of 103 meters / minute. After 3 minutes of cutting at a surface speed of 152 meters / minute, the corresponding figures show a cutting edge wear of

  <Desc / Clms Page number 49>

   0.2286 mm, a crater width of 0.6958 µm and a proton-. 0.1905 mm crater depth.

   After cutting for 30 seconds at a surface speed of 304 meters / minute, the figures have; a wear of the: '' bit of 0.1016 mm, a crater width of 0.5080 mm and a crater depth of 1.27 cm. Even after cutting at a surface speed of 456 meters / minute, the usu-. The cutting edge after 1 minute, cutting is only 0.348mm ,,. the crater width approximately 0.5588mm. and the crater depth -from 25.4 microns to 12.7 microns.



   Metallographic examination of this refractory dispersion shows a much more uniform distribution of the metallic component throughout the structure than in the previous examples. The result of using the finer particle size metallic tungsten powder is also shown by the smaller average particle size of the metal which is from less than one micron to about 4 microns, and that of the non-metallic constituents. which all have an average caliber appreciably less than 2 microns.



   This refractory material represents one of the preferred embodiments of the invention. It has a phase. continuous metal-as shown by its extremely low electrical resistivity of 0.034 ohm-cm. Improved distribution and. the effect of a continuous metallic phase can also be noted in the strength, the transverse fracture which is rather double and the increase in hardness, and in the use of this dispersion as a cutting tool, when 'this example is compared to Example 22.

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    EXAMPLE 24.



   61 grams of the metallic tungsten powder prepared as described in Example 23 are mixed with 5 grams of metallic chromium powder with a caliber of -0.044 mm, and with 34 grams of the aluminum nitride composition. prepared as described in Example 21. This mixture is ground in 300 cc of a high boiling point hydrocarbon type solvent placed in a rubber-lined steel ball mill with a capacity of 1.1 liters. The mill is filled to 40% of its volume with alumina balls with a diameter of 0.635 mm.

   After grinding for 14 hours at a speed of 60 revolutions per minute, the intimate grinding of tungsten and aluminum nitride is recovered by centrifugation and washed with hexane until the product obtained is free. hydrocarbon type oil used as a grinding agent. 25 grams of this composition are hot pressed under the conditions described in Example 21. The refractory material obtained consists of approximately 2.67 parts by volume of aluminum nitride per part by volume of an alloy. chromium-tungsten containing 13.2% by weight of chromium.



   The average tensile strength of this refractory is 4,707.5 kg / cm2, its impact strength is 6.344 kg-m / cm2, its Rockwell A hardness is 88.9 and its density is 6. 87 g / cm3, which represents 97.44% of the theoretical density.



     A metallographic examination of the structure of the refractory dispersion shows an extremely uniform interdispersion of the metal and the aluminum nitride, the particle size of the nitride being between about 2 to 4 microns, and that of the metal being between less than 1 micron and about 10 microns. The existence of a metallic phase

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 continuous is shown by measuring the electrical resistivity, which is 0.035 ohm-cm.

   It should also be noted that, by comparing this example with Examples 21 and 22, the tensile strength and the impact resistance improved :; such as, use as a cutting tool, discussed below,
A portion of this refractory material is machined to prepare a cutting tool insert and tested as Example 21. The following results are obtained: At a speed of 103 m surface area per minute, the usu-. The cutting edge is 0.1524mm, the crater width is 0.635mm, and the crater depth is 12.7 microns, after cutting for 3 minutes.

   When cutting for 3 minutes at a surface speed of 152 m / minute, the bit wear is 0.2032 mm, the crater width is 0.6958 mm, and the crater depth is 25, 4 microns. During a cut of .1 minute at a surface speed of 456 meters per minute, the bit wear is 0.635 mm, the crack width is 0.4572 mm and the crater depth is is .25.4 microns.



     EXAMPLE 25.



   20 grams of silicon carbide particles with a particle size of 1/10 of a micron are ground for 4 days with 380 grams of pigment in the form of aluminum rods, similar to that used in Example 21.



   5.5 g of a 37% dispersion of metallic lithium in paraffin wax are also added. carried out with 9300 g of steel balls and 1700 cm3 of a high boiling point hydrocarbon type oil as grinding fluid, Grinding is carried out in a steel grinder with a capacity of 3, 78 liters and the composition is ground for 4 days, after which the aluminum mixture

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 and silicon carbide is recovered from the grinding oil and washed until oil-free with hexane.

   150 g of this material are reduced in a carbon basket to
1450 C for a period of 8 hours under an atmosphere of nitrogen and cracked ammonia. The product obtained is a solid solution of 5% silicon carbide in aluminum nitride. The size of the agglomerated silicon carbide and aluminum nitride particles is about 40 microns.



   27.7 grams of this material and 4.05 grams of metallic chromium powder with a caliber of - 0.044 mm are ground in a rubber-lined steel crusher with a capacity of 1.1 liters, filled to 40% of its volume with alumina balls of 0.635 mm caliber and containing 350 cm3 of a high boiling point hydrocarbon type oil. Grinding is carried out at a rate of 60 revolutions / minute for a period of 2 days.

   After recovery of the product from the balls and washing separation of the high boiling point hydrocarbon type solvent, the final powder was found to have a volume percent composition which is as follows: 85.5% by volume of the powder. powder consists of the solid solution of 95% aluminum nitride and 5% silicon carbide, 5.7% by volume consists of metallic chromium and 8.7% by volume consists of a finely shaped di- vision of alumina collected from the alumina balls.



   15 g of this composition are pressed in a manner substantially similar to that described in Example 21, except that the pressure of 280 kg / cm2 is imposed at 1800 C and the temperature at which the sample is held for
5 minutes is 1900 C. The dispersion obtained is constituted

  <Desc / Clms Page number 53>

 
 EMI53.1
 1 of 14.25 partial by volume of aluminum nitride, about 1.53 parts by volume of alumina and 0.75 parts by volume of carbide, of silicon per part by volume of chromium me...



   The dispersion has an average transverse breaking strength of 3540 kg / cm2, a Rockwgll A hardness of 90.1, an impact resistance of 1.872 kg-m / cm2 and a density of 3.28 g / cm3. , which corresponds, with respect to the theoretical density of
3.54 g / cm3 intended for the above dispersion at a percentage of the theoretical density of 95.5%.



   EXAMPLE 26.



   Using the same starting materials as those employed in Example 25, 24.2 grams of the solid solution of aluminum nitride and silicon carbide of Example
25 are ground with 17.8 g of metallic chromium, with a particle size of - 0.044 mm, in a rubber-lined ball mill with a capacity of 1.1 liters and 350 cm3 of fine hydrocarbon type solvent. high boiling. The mill is filled to 40% of its volume with steel balls having a diameter of 4.762 mm and the milling is carried out for a period of 24 hours at a speed of 60 rpm.

   After recovering the intimate, finely divided mixture of chromium, aluminum nitride and silicon carbide from the steel balls and the hydrocarbon type solvent, washing with hexane and drying in a vacuum oven. Analysis shows that the dispersion obtained contains 2.24 parts by volume of aluminum nitride and 0.1 part by volume of silicon carbide per part by volume of metal. The metal is made up of
78% by volume of chromium and 22% by volume of iron.

  <Desc / Clms Page number 54>

 
 EMI54.1
 



  20 grams of this dispersion are pressed as in Example 25 and the refractory dispersion obtained has a Ro @ kwell A hardness of 89.6, an impact resistance of 15.6 kg-met @ / cm2, a resistance to the average transverse rupture of @ 00 kg / cm2 and a density of 4.34 g / cm3 which corresponds with respect to the theoretical density of 4.44 g / cm3 expected for this refractory dispersion, at a percentage of the theo- density risk of 98.0%.



  EXAMPLE 27.



  77.2 grams of the metallic tungsten of the example. 23 are ground with 19.5 grams of the aluminum nitride of Example 21. The grinding is carried out in a ball mill lined with rubber with a capacity of 1.1 liters, filled to 40% of its volume. with steel balls of 4.762 mm caliber and 350 cm3 of a high boiling point hydrocarbon type oil. Grinding is carried out at 60 revolutions per minute for 24 hours.

   The powder obtained from aluminum nitride and tungsten mixed intimately is recovered from balls and washed until the solvent of the hydrocarbon type is free with hexane and dried in a vacuum oven 36 grams of the powder obtained consisting of 1, 5 part by volume of aluminum nitride per part by volume of tungsten, are pressed under the conditions described in Example 21, except that the maximum imposed pre @ don is 420 @ / cm2 .



  The dispersion refracted: ;, this obtained has a resistance to. rupture of 10,360 kg / cm2, impact strength of 7.696 kg / cm2, Rockwell A hardness of 85.6 and density of 9.46 g / cm3, which represents 98% of theoretical density of 9.67 g / cm3 calculated for this refractory material. The refractory su stance is tested as a tool cut on cast iron; it performs exceptionally well even with interrupted cuts and at high speeds.

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  EXAMPLE 28.



   1360grams of metallic molybdenum powder with a particle size of -0.044 mm are placed in a steel ball mill with a capacity of 3.78 liters filled to 40% of its volume with steel balls and also containing 1800 cm3 of a high boiling point hydrocarbon type oil. This mixture is ground at a speed of
60 rpm for 3 days, after which the molybdenum powder is separated from the hydrocarbon type oil and steel balls, washed completely with hexane to remove the oil and dried in a vacuum oven . It is purified, with hydrochloric acid and water treatment identical to that described in the purification of tungsten metal powder of Example 23.

   The finely divided metallic molybdenum powder obtained has an average particle size of 100 to 200 millimicrons and contains no. only traces of iron as impurities.



  * 40.8 grams of this material are ground with
19.5 grams of aluminum nitride prepared as described in Example 21, in a rubber-lined steel ball mill with a capacity of 1.1 liters filled to 40% of its volume with balls of 4.762mm caliber steel.



   The grinder also contains 350 cc of a high boiling point hydrocarbon type oil, Grinding is carried out for a period of 24 hours at a speed of
60 revolutions / minute. After recovering the thoroughly mixed powder of molybdenum and aluminum nitride from the hydrocarbon oil, washing with hexane to remove the oil and drying in a vacuum oven, 25 grams of , this material are hot pressed under the conditions described in Example 21.

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   The resulting refractory dispersion contains about 1.5 parts by volume of aluminum nitride per part by volume of molybdenum. The dispersion has an average transverse tensile strength of 5447.75 kg / cm2, an impact strength of 11.648 kg-m / cm2, a Rockwell 'A hardness of 83.2 and a density of 5.97 g. /cm3. Compared to the theoretical density expected for this composition, which is 6.03 g / cm3, this represents 99% of the theoretical density.



    EXAMPLE 29.



   21.2 g of the aluminum nitride powder of Example 21 are mixed with 24.9 g of pure metallic chromium with a particle size of -0.044 mm. This ground powder is recovered as in the previous example. It is hot pressed by introducing carbon into the mold at 1600 C, heating to 1800 C, applying a pressure of 280 kg / cm2, increasing the temperature to 1900 C and maintaining this temperature for 5 minutes. The resulting dispersion has a tensile strength of 9240 kg / cm2, an impact strength of 15.6 kg-m / cm2, a Rockwell A hardness of 90.1 and a density of 4.61 g / cm3, which represents 100% of the theoretical density. The dispersion contains about 1.86 parts by volume of aluminum nitride per part by volume of metal chromium.

   This dispersion constitutes an excellent high temperature refractory material which exhibits high oxidation resistance as well as high resistance even above 1100 C.



  EXAMPLE 30.



   41.5 g of the metallic tungsten powder of Example 23 and 22.10 g of the aluminum nitride powder of Example 21 are mixed with 17.8 g of metallic rhenium powder with a particle size of -0.044 mm and ground under the same conditions as in Example 21. @ The conditions of

  <Desc / Clms Page number 57>

 pressing are also the same as those employed at. Example 21, except that a holding time of 15 minutes at 20000C is used instead of a holding time of 5 minutes at this temperature. The resulting refractory dispersion contains about 2.33 parts by volume of aluminum nitride per part of aluminum of an alloy consisting of 70% by weight of tungsten and 30% by weight of rhenium.

   Its transverse breaking strength is 14,000 kg / cm2, its Rockwell A hardness is 91.5, its impact resistance is 46.8 kg-m / cm2, and its density is 7.20 g / cm3. , which represents more than 99.5% of the theoretical density expected for this composition. X-ray examination shows that this dispersion consists of aluminum nitride and a tungsten-rhenium alloy phase. This dispersion is used as a cutting tool to cut cast iron, stainless steel, 4340 steel as well as various nickel and chromium base super alloys containing aluminum and titanium. - me precipitation hardening agents.

   Its use as a cutting tool on these metals is remarkable, with wear being almost negligible even at the highest cutting speeds on all of these metals except superalloys.



   Even with these extremely hard and strong alloys, it has been found possible to cut without excessive wear at high speeds.



   EXAMPLE 31.



   31 grams of the aluminum nitride powder of Example 21 and 3.85 grams of the molybdenum powder of Example 28 are mixed with 2.48 grams of pure rhenium powder with a particle size. -0.044 mm..These materials are ground in a steel mill lined with rubber with a

  <Desc / Clms Page number 58>

 1.1 liter capacity filled to 40% of its volume with 4.762 mm steel balls and containing 350 cm3 of a high boiling point hydrocarbon.

   The grinding is carried out for 24 hours at a rate of 60 revolutions / minute and the cutting of the intimately mixed powder of metal and aluminum nitride is carried out as indicated in the preceding examples.



   15 grams of this composition are pressed at 2000 C for a period of 5 minutes, after first applying a pressure of 280 kg / cm2 at a temperature of 1900 C. The resulting dispersion has a breaking strength. re of 4200 C, an impact resistance of 15.6 kg-m / cm2, a density of 3.70 and a Rockwell A hardness of 89. The dispersion consists of 19 parts by volume of aluminum nitride per part by volume of a rhenium alloy and. molybdenum in a ratio of 40 to 60 and the density obtained corresponds to 99% of the expected theoretical density. for this composition.

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   EXAMPLE 32
19.5 grams of the silicon carbide and aluminum nitride powder of Example 25 are mixed with 17.7 g of chromium metal powder, with a particle size of −0.044 mm and 5 g of commercial magnesium nitride. This mixture is ground in a rubber-lined grinder with a capacity of 1.1 liters containing 350 cm3 of a high boiling point hydrocarbon and filled to 40% of its volume with dumplings. 'steel of a' gauge of 4.762 mm, for a per @ ole of 24 hours at a speed of 60 revolutions / minute.



   After recovering and washing the powder as described in the previous examples, 17 g of this powder are pressed into a carbon mold at a temperature of 1900, however for a period of 5 minutes. The reactionary dispersion obtained shows a resistance to transverse rupture of
7210 kg / cm2, an impact resistance of 12.48 kgm / c @ 2, a Rockwell A hardness of 91-.0 and a density of 4.2 cm3, which is very close to 100% of the theoretical density that we are waiting for this composition.

   It should be noted that the non-metallic constituents of the dispersion constitute 3 parts by volume per part by volume of metal.



   EXAMPLE 33.



   2.48 g of pure metallic chromium powder with a caliber of'-0.044 mm and'3.5? g of the metal molybdenum powder prepared in Example 28 are mixed with 30.3 g of aluminum nitride prepared as described in Example 21. The grinding conditions, recovery from the solvent and the - pressing are substantially identical to those described in Example 21. After pressing, the dispersion obtained contains - about 13.3 parts by volume of aluminum per part by volume.

  <Desc / Clms Page number 60>

 lume of an alloy which is 50 vol% chromium and 50 vol% molybdenum.

   The transverse breaking strength of this dispersion is 7140 kg / cm2, its impact resistance is 7.28 kgm / cm2 and its Rockwell A hardness is 88.5. The density of 3.60 g / cm3 represents 99.3% of the theoretical density of this composition. This dispersion shows high temperature resistance together with excellent oxidation resistance, even at temperatures over 10,000 C.



   ......



   EXAMPLE 34: 13.45 g of the metal tungsten powder of Example 23, and 7.65 g of the metal molybdenum powder of Example 28 are mixed with 27.7 g of the metal powder. aluminum nitride of Example 1 and these substances4 are ground in a rubber-lined grinder with a capacity of 1.1 liters filled to 40% of its volume with steel balls with a caliber of 4.762 mm and containing 350 cm3 of a high boiling point hydrocarbon. The grinding is carried out for a period of 24 hours at a speed of 60 revolutions per minute. After the recovery of the intimate mixture of aluminum nitride and metal in powder form, as described in the preceding examples, 18 g of this composition are pressed under the pressing conditions described in example 21.

   The refractory dispersion obtained shows a tensile strength of
5250 kg / cm2, a Rockwell A hardness of 90, an impact resistance of 4.16 kgm / cm and a density of 4.83 g per cm3, which corresponds to 97% of the theoretical density expected for this composition. This dispersion contains approximately 5.67 parts by volume of aluminum nitride per part by volume of an alloy consisting of 50% by volume of molybdenum and 50

  <Desc / Clms Page number 61>

 by volume of tungs @ ene.



   E X E M P L E 35.



   5.10 g of the molybdenum powder of Example 28 are mixed with 0.12 g of zirconium hydride and 31.0 g of the aluminum nitride powder of Example 21. These substances are crushed and separated from the oil as described in the previous example. The pressing conditions used are those of Example 21. The dispersion obtained, consisting of 5% by volume of an alloy with 98% molybdenum 'and 2% zirconium, has a breaking strength of 4900 kg / cm2, a Rockwell A hardness of 91, an impact resistance of 10.4 kgm / em2 and a density of 3.61 g / cm3, a value which is very close to 100% of the theoretical density expected for this composition.



   EXAMPLE 36.



   26 g of the metallic molybdenum powder of Example 28 are ground with 24.4 g of the aluminum nitride powder of Example 21 and to this mixture 0.6 g of hydride is added. of zirconium. This mixture is crushed and recovered as described in the preceding examples and 20 g of this mixture is pres-. ses at 2000 C, using the pressing cycle described in Example 21 '. The refractory dispersion obtained shows a transverse breaking strength of 11,210 kg / cm, an impact strength of 31.20 kgm / cm, a Rockwell A hardness of '90.5 and a density of 5.05 g per cm, which represents 99% of the theoretical density.

   The dispersion contains 25% of an alloy of molybdenum and zirconium which consists of 98% by weight of molybdenum. -
The dispersion is exceptionally attractive as a cutting tool on a variety of metals and alloys with minimal wear. The alloys tested include

  <Desc / Clms Page number 62>

 nent bronze, an abrasive copper-aluminum alloy, precipitation hardened, a cobalt superalloy containing chromium and tungsten as well as carbon as hardening agents, cast iron, and 4340 steel. minor wear using cutting speeds up to 456 m surface per minute on all alloys except the cobalt based superalloy. This alloy can be cut with relatively low 'wear' at a speed of up to 122 surface meters per minute.

   This cutting tool composition is particularly noteworthy in interrupted cuts on steel and cast iron, due, it is believed, to its impact resistance, high mechanical strength and hardness.



     EXAMPLE 37.



   19.6 g of aluminum nitride from Example 21 are mixed with 22.6 g of titanium hydride powder and these substances are ground in a grinder lined with rubber with a capacity of 1, 1 liter filled to 20% of its volume with 4.762 mm gauge steel balls in 350 cc medium of high boiling point hydrocarbon type oil.



   Grinding is carried out for 4 days at a speed of 60 revolutions / minute. The intimate mixture obtained of titanium hydride and aluminum nitride is recovered from the beads or balls in the mill and washed until it is free of oil with hexane. This mixture is then loaded into an alumina tube ¯, gas-tight in alumina boats and is nitrided at a temperature of 8500 C for a period of b hours under an atmosphere of cracked ammonia. At the end of the 8 hour period the temperature is raised to 12000 C, while maintaining the atmosphere of cracked ammonia and nitriding.

  <Desc / Clms Page number 63>

      is carried out pedant 4 additional hours.

   The oven is cooled and the product removed. Chemical analysis and identification of the X-ray diffraction shows that the powder consists of 60% by volume aluminum nitride and 40% by volume titanium nitride. The size of the crystallites of the two phases is less than 1 micron, as de- '. ended by the widening of the lines during the x-ray examination.



   28.8 g of this powder are mixed with 21.3 g of pure metallic chromium powder of 0.044 mm caliber and these substances are ground together for 3 days in a ball mill lined with rubber. a 1.1 liter capacity containing 350 cc of a high boiling point hydrocarbon solvent and filled to 40% of its volume with 4.762 mm caliber steel balls. The grinding speed is 60 revolutions / minute. The product is then recovered and washed until it is free from oil with hexane and dried in a vacuum oven.



   20 g of this mixture are pressed at a temperature of
1900 C, with a holding time of 5 minutes and a pressure of 280 kg / cm. The pressure of 280 kg / cm2 is first imposed at 1800 ° C. after the carbon mold containing the powder has been introduced into the hot zone of the oven.



   The resulting dispersion contains 0.93 parts by volume of titanium nitride and 1.4 parts by volume of aluminum nitride per part by volume of chromium, which is present in. form of a continuous network or vehicle. The dispersion has a transverse tensile strength of 14,000 kg / cm2, an impact strength of 15.6 kgm / cm, a Rockwell A hardness of
91 and a density of 4.97 g / cm3, which represents 99.2% of the theoretical density expected for this composition.

  <Desc / Clms Page number 64>

 



   E X E M P LE 38.



   This example illustrates the preparation of a dispersion containing 30% by volume of metallic chromium and 70% by volume of a dispersed refractory phase consisting of 60% by volume of aluminum nitride and 40% by volume of nitride. of zirconium. 19.6 g of the aluminum nitride of Example 21 are mixed with 29.1 g of zirconium hydride and this mixture is ground and recovered from the mills as mentioned in the previous example. The nitriding of this mixture is also carried out as described in Example 37.

   After nitriding, chemical analysis and X-ray examination show that the powder obtained consists of an intimate mixture of zirconium nitride and aluminum nitride in the ratio of 40% by volume of nitride. of zirconium at 60% by volume of aluminum nitride. Both nitride phases have particle sizes less than 1 micron as shown by line widening on x-ray examination.



   33.6g of this material is combined with 21.3g of high purity metallic chromium of -0.044mm caliber and these materials are ground in a ball mill and recovered as described in Example 37.



   23 g of this product are hot pressed using a pressure of 35 kg / cm2, a temperature of 1600 C and a hold time. 30 minutes at maximum temperature and pressure. The refractory dispersion obtained shows a transverse breaking strength of 12,600 kg / cm2, a hardness of 90.5 on the Rockwell A scale and an impact resistance of 13.52 kg-m / cm2. The density is 5.45 g / cm3, which represents 99.4% of the theoretical density expected for this composition. The dispersion combines high resistance ###### '

  <Desc / Clms Page number 65>

 with reasonable ductility and excellent oxidation resistance even at temperatures over 1000 C.



   E X E M P L E 39.



     317.15 g of chromic pirate, 7.5 water of hydration are dissolved in 1 liter of water. A second solution consisting of 6.6 g of magnesium nitrate and water of hydration is also dissolved in 1 liter of water. These two solutions are poured simultaneously and in equal ratios into a 3 liter bottom consisting of a solid solution of ammonium bicarbonate. The precipitates obtained from the basic carbonates of magnesium and chromium intimately mixed with each other are washed completely to remove the dried ammonium salts in a vacuum oven. They are then heated to a temperature of 2500 C to decompose the basic chromium carbonate.

   This mixture is reduced in hydrogen by slowly raising the temperature at a ratio of 2000 C per hour to a peak temperature of 1200 C. The sample is then maintained at this temperature for 18 hours and cooled. Chemical analysis and X-ray diffraction show that the powder obtained consists of an intimate, uniform and fine dispersion of 2% of magnesium oxide in pure metallic chromium.



   10.65 g of this powder are mixed with 28.7 g of the aluminum nitride powder of Example 21 and the mixture is ground and recovered as described in the preceding examples. 18 g of this mixture are pressed at a temperature of 1800 C and a pressure of 280 kg / cm2, with a holding time of 15 minutes at 18000 C. A pressure of 280 kg / cm is first applied. at a temperature of 1700 C: The refractory dispersion obtained consists of particles of aluminum nitride mutually dispersed with metallic chromium which has, dispersed in the mass, finely divided crystals of magnesium oxide.

   The trans-

  <Desc / Clms Page number 66>

 versal dispersion is 8610 kg / cm2, impact resistance is 31.2 kg / cm2, Rockwell A hardness is 90, and density is 3.93 g / cm3, which roughly corresponds to the density theoretical expected for this composition.



   E X E M P L E 40.



   48.2 g of a sample of metallic tungsten powder containing, dispersed in its mass, 1% by weight of particles with a size of 100 millimicrons of thorium oxide are mixed with 24.5 g of aluminum nitride of Example 21. This mixture is ground for 24 hours in a rubber-lined grinder with a capacity of 1.1 liters containing 350 cm3 of a high boiling point hydrocarbon solvent. and filled to 40% of its volume with steel balls of a caliber of -1.5875 mm. The grinding speed is 60 revolutions per minute.

   After the recovery and removal of the oil as described in the previous examples, 25 g of this material are pressed at a temperature of 2200 C with a holding time of 1 minute at the peak temperature under a pressure. 280 kg / cm2 which is first introduced at 2000 C. The refractory dispersion obtained consists of approximately 0.09 part by volume of thorium oxide and 3.26 parts by volume of. aluminum per part by volume of metallic tungsten. The transverse breaking strength is 7700 kg / cm2, its density is 7.20 g / cm3, its Rockwell A hardness is 90.9, and the impact resistance is 20.8 kg-m / cm2. The density represents 96.2% of the theoretical density expected for this composition.



    EXAMPLE 41.



   20.4 g of a sample of finely divided molybdenum powder containing, in the dispersed state, 10% by weight of thorium oxide in the form of discrete crystals of a size of 100 millimicrons, are mixed to 26.1 g of nitride

  <Desc / Clms Page number 67>

 aluminum 'of \.;

   Example 21 and these materials are crushed, recovered from the biibyeur and washed until they are free of oil as will be described in the previous example, 18 g of this material are pressed under the conditions described in the previous example and the dispersion refractory obtained shows a transverse breaking strength of 6300 kg / cm2, a Rockwell A hardness of
91.5, an impact resistance of 15.6 kg-m / cm2 and a density of 4.63 g / cm3. This density represents 99.5% of the theoretical density provided for this composition.

   The dispersion consists of 20% by volume of a molybdenum binding metal phase containing, in the dispersed state, 10% by weight relative to the weight of the molybdenum of distinct particles of thorium oxide with a size of 100 to 200 millimicrons, and a refractory phase comprising 80% of the dispersion of finely divided aluminum nitride particles. This material exhibits high strength as well as exceptional resistance to blistering, even at temperatures up to 1500 C in inert atmospheres.



   . EXAMPLE 42.



   322.7 g of the aluminum nitride of Example 21 and
19.2 g of the metallic tungsten of Example 23 are ground using 2500 g of cylindrical-shaped rod-shaped elements or rods made of cobalt and tungsten carbide and 350 cc of a type oil. High boiling point hydrocarbon in a 1.1 liter capacity rubber lined steel ball mill. Grinding is carried out for a period of 500 hours at a speed of 60 revolutions per minute.

   The ground mixture of tungsten and aluminum nitride is recovered as described in the preceding examples. '

  <Desc / Clms Page number 68>

 
The intimately mixed powder obtained consists of 99 parts by volume of aluminum nitride and * of 1 part. by volume of metallic tungsten, both phases having particle sizes of less than 1 micron. 14 g of this powder are pressed in a nitrogen atmosphere, the pressure being applied at a temperature of 2000 C. A pressure of 280 kg / cm2 is used.



   The dense body obtained according to the invention consists of a dispersion of 99 parts by volume of aluminum nitride in one part by volume of metallic tungsten.



  Its density is 3.42 g / cm3, which is the theoretical density provided for the composition. This body is hard and strong, resists corrosion and erosion and is well suited for high temperature structural applications.



   EXAMPLE 43.



     244.5 g of the aluminum nitride of Example 21 and.



    19.2 g of the metallic tungsten from Example 23 are mixed, ground and recovered from the mill as described in the previous example. The pressing is also carried out under the same conditions and the dense body obtained according to the invention consists of a dispersion of 75 parts by volume of aluminum nitride in one part by volume of metallic tungsten. The density of the hot-pressed body is 3.34 g / cm3, which represents the theoretical density of this composition. This composition is stronger, more ductile, but otherwise similar in properties and utility to the composition of Example 42.



   EXAMPLE 44.



   An ammonium tungstate solution is prepared by dissolving tungsten oxide in an excess of concentrated ammonium hydroxide. This solution contains 11.2% tungstic oxide. 6317 g of the ammonium tungstate solution are adjusted to a volume of 6 liters. 1821 g of 22% titanium oxide sol, the titanium oxide being in the form of spherical aggregates with a size of 20 millimicrons of ###############

  <Desc / Clms Page number 69>

 particles of size 5 to 10 millimicrons are mixed with 1713 g of a so. 3.5% alumina, the alumina being in the form of particulates with a size of 20 millimicrons. The pH of the mixed soils adjusted to 1 with hydrochloric acid and the mixture is then adjusted to a total volume of 6 liters.



   2970 cm3 of an 18.5% aqueous hydrochloric acid solution is adjusted to 6 liters n volume with water. A bottom of 6 liters of distilled water adjusted to a pH of 1 with hydrochloric acid.



   The solution of the mixed salts of titanium oxide and alumina, the solution of ammonium ignstate and the solution of hydrochloric acid and the water are poured at equal flow rates simultaneously into the aforementioned section vigorously. restless.



   The resulting precipitated mixture of tungstic oxide, titanium dioxide and alumina is washed by decantation and centrifugation, and dried in an air oven overnight at 250 - 300 C.



   The weight recovered at this stage is 1076 g. This material is then calcined in an oven at 400 - 450 C overnight and the weight decreases to 956 g. This material is then reduced with the aid of hydrogen in an electrically heated oven in a stream of pure dry hydrogen, first at 600 C and finally at 1000 C. Under these conditions, the tungstic oxide is transformed. tungsten metal in a colloidal mixture with titanium monoxide and alumina.



   826 g of this mixture are recovered and analysis shows that it has an oxygen content of 22.1% at this stage.



     141 g of carbon are mixed with this material and the mixture is heated in a tubular ceramic furnace in a nitrogen atmosphere at a temperature of 1250 C.



   The atmosphere is then replaced by an ammonia atmosphere and the system is maintained at 1250 C for 15.5 hours, after which it is heated to 1550 C and maintained at

  <Desc / Clms Page number 70>

 this temperature for 22.5 hours.



   The product obtained is an intimate colloidal mixture of metallic tungsten and titanium nitride, with a small amount of alumina and aluminum nitride. X-ray examination of this powder shows that it consists of crystallites of tungsten, 30 millimicrons in diameter, together with titanium nitride, 17.5 millimicrons in diameter. Alumina. and aluminum nitride are below the X-ray detection limit.



   The product is somewhat agglomerated, as indicated by its nitrogen surface area of 2 m2 / g, which is considerably less than that which would be obtained with a mixture of crystals. non-agglomerated of the caliber indicated by x-rays.



   274 g of this composition, 1.5 g of a pure cobalt powder of 1 micron caliber and 4996 g of tungsten sticks or rods are charged into the rubber-lined ball mill, together with 180 cm3 of an oil of the non-volatile hydrocarbon type. The capacity of the crusher is approximately 1300 cm3. The grinding is carried out at a speed of 60 revolutions / minute for 5 days.



   During grinding, 13g of tungsten is collected by the product, from the tungsten sticks due to partial attrition during grinding. This powder was found, during chemical analysis, to be composed of
2.59 parts by volume of titanium nitride and 0.58 parts by volume of alumina per part by volume of the metal which consists of 98% by volume of tungsten and 2% by volume of cobalt. The predicted theoretical density for this composition, which is calculated assuming that the specific volumes of the components can be added, is 8.50 g / cm3.

  <Desc / Clms Page number 71>

      



   A number of refractory samples are made from this powder by hot pressing it at a temperature of 1800-1845 C, using a pressure of 280 kg / cm2 and a hold time at this temperature of 1 minute. The average properties obtained are as follows :. the density is 8.52 g / cm3, the Rockwell A hardness is 90, the transverse breaking strength is 11,060 kg / cm2, and the impact strength is 38.48 kg-m / cm2.



   This refractory dispersion constitutes an excellent cutting tool as shown in the following tests. The samples of hardened steel, 4340 grade, Brinnel hardness 351 are machined on a lathe using a feed of
0.254 mm, a cutting depth of 1.2? mm and a speed expressed in surface meters / minute of approximately 274 meters.



   After 3 minutes of cutting, the average wear of the cutting edge or cutting edge is about 0.127 mm, the highest local wear observed is 0.1524 to 0.2032 mm and the crater depth is about 31.75 microns. ,
In a one-lathe machining test, in which the feed is 0.762 mm, the depth of cut is 3.175 mm, and the surface speed of 91.2 meters per ninute, a machining of 1 minute results in .a-local wear of 50.8 microns and an average wear of 50.8 microns; as well as zero crater depth.

   Tool life curves are calculated on the same steel, using a surface speed of 152 meters per minute, a feed rate of
0.508mm and a cutting depth of 1.587mm, and the tool operates without failure for a period of 19 minutes and 45 seconds. At the end of this test, wear and crater formation are not excessive; although a slight peeling -

  <Desc / Clms Page number 72>

 causes some deterioration of the surface finish of the refractory dispersion at this stage. Under conditions, similar to a surface speed of 121.6 ours per minute, the life of this refractory is 14 minutes and 15 seconds.



   As a further indication of the excessively high strength of this tool, it is used as a single tooth in a milling head to cut malleable iron to a cut depth of 0.254 cm. , a feed rate of 1.016 mm per tooth, and a speed of 60 surface meters per minute. No crater wear @ observable bit wear and no bit failure followed, even after a 1.68 cm cut of metal, the es @ i being completed by this time.



   Therefore, this utility functions in a remarkable fashion in the case of. practical grinding conditions of the harshest type and in those conditions where only the most wear resistant ceramic tools are normally used.



   EXAMPLE 45.



   An aci @ ball mill with a volume of
1.3 liters is charged with 114 g of finely divided titanium nitride, 17.1 g of aluminum nitride and 90 g of tungsten ground in a ball mill. 450 g of a hydrocarbon oil having a flash point of 130 ° C. and 5.75 kg of tungsten elements are also charged to the mill.
This mixture is ground in a mullet mill for 5 days.

   Product recovery is carried out by transferring the suspension from the ball mill to a resin kettle, the suspension is deposited and the liquid which supersedes is removed by a siphon. The wet cake is washed thoroughly with hexane and then dried in vacuo. The resin cauldron containing the dry powder is

  <Desc / Clms Page number 73>

 opened in an inert atmosphere in a dry box and the resin is sieved through a 0.210 mm sieve.



   A sample of this 0.210 mm powder dispersion is hot pressed according to the following method: the sample is heated to 1900 ° C. in a graphite mold and maintained at this temperature for 6 minutes. A pressure of 280 kg / cm2 is then applied and maintained for a total of 5 minutes, the sample is then allowed to cool rapidly. These operations are carried out in a half atmosphere of nitrogen.



   The obtained sample has a transverse tensile strength of 9527 kg / cm2, an impact strength of 6.24 kg-m / cm2 and a Rockwell A hardness of dE 90.1. The density of 7.7 g / cm3 is equal to 100 of the theoretical density expected for this eompo-. sition, which contains about 3.0 parts by volume of titanium nitride and about 0.8 part by volume of aluminum nitride per part by volume of tungsten.



   This refractory dispersion is used to make a cutting tool insert and used as a cutting tool. pant on 4340 steel. It makes an excellent high speed cutting tool at 274 surface meters per minute, using a feed of 0.254 cm / revolution and a depth of cut of 1.27 mm. After 3 minutes of operation, the tool. has an average bit wear of 0.1778 mm and a crater depth of 25.4 microns. At a surface speed per minute of 91.2 meters, also on quality steel
4340, using a heavy feed of 0.762mm and a cutting depth of 3.175mm, this tool cuts satisfactorily. , health and resists breaking.

   After a minute, the tool cut off. has an average cutting edge wear of only 76.2 microns @ t none,

  <Desc / Clms Page number 74>

 wear by measurable crater formation,
This tool operates for 30 minutes without failure on 4340 steel at a speed of 112.5 surface meters / minute, with a cutting depth of 3.175 mm and a feed of 50.8 microns and it exhibits wear. cutting edge of only 91.6 microns and a crater depth of 25.4 microns. The finish of the workpiece is excellent.



     EXAMPLES 46 - 60.



   The following examples illustrate other compositions which are prepared in a similar manner to that described. in Example 1. 'The specific conditions used in the grinding and hot pressing operations, the chemical analysis of the powder, and the nominal composition as well as the properties of the pressed parts are given in the tables given below. -after.

   The operation of the refractory dispersion in the form of a cutting tip is described separately for each example,

  <Desc / Clms Page number 75>

 
 EMI75.1
 1-1 TABLE
 EMI75.2
 
 <tb> Exem- <SEP> Quantities <SEP> of <SEP> materials <SEP> of <SEP> Conditions <SEP> of <SEP> treatment <SEP> Analysis <SEP> of <SEP> the <SEP> powder <SEP> Calibers <SEP> of
 <tb> ple <SEP> departure <SEP> (grams) <SEP> in <SEP> a <SEP> crusher <SEP> to <SEP> cannonballs <SEP> crystals <SEP> determined <SEP> by <SEP> exam
 <tb> to <SEP> spokes <SEP> X.
 <tb>



  . <SEP> TiN <SEP> AIN <SEP> Al2O3 <SEP> 'He <SEP> Co <SEP> El- <SEP> Weight <SEP>!) Urea <SEP> of <SEP>% <SEP> C <SEP>% <SEP> 0 <SEP>% <SEP> N <SEP> 'Surface <SEP> TiN <SEP> W <SEP> '' <SEP>
 <tb>
 
 EMI75.3
 elements (gram- grinding of N 2 (m2 / g .. ## - # - - '¯¯¯ ..' - ¯ ¯ ¯, nies) ¯¯ ¯¯¯¯¯¯
 EMI75.4
 
 <tb> 45 <SEP> 114 <SEP> 17.1 <SEP> - <SEP> 90.0 <SEP> - <SEP> W <SEP> '5.75 <SEP> 5 <SEP> days <SEP> 1.15 <SEP> 1.68 <SEP> 10.26 <SEP> 10 <SEP> 19 <SEP> 30
 <tb> 46 <SEP> ' <SEP> 114 <SEP> 17.1 <SEP> - <SEP> 90.6 <SEP> 1.6 <SEP> W <SEP> 5.58 <SEP> 6 <SEP> days <SEP> 1.34 <SEP> 1.80 <SEP> 8.64 <SEP> 8.6 <SEP> -
 <tb> 47 <SEP> 66.6 <SEP> 9.9 <SEP> - <SEP> 90.0 <SEP> - <SEP> W <SEP> 7.86 <SEP> 5 <SEP> days <SEP> 1.11 <SEP> 2.01 <SEP> 8.37 <SEP> 11 <SEP> 27
 <tb>
 
 EMI75.5
 48 89.5 17.4 fui '- 125 - W 6, 64 5 days 0, 24 3.12 9, 07' = r 22 30 -.



  49 64.0 6t2 60 - W 7.00 16 hours 0.81 0.80 11.39 - 5, 6 37 29
 EMI75.6
 
 <tb> 50 <SEP> 72.8 <SEP> 7.0 <SEP> - <SEP> 77.2 <SEP> - <SEP> WC <SEP> ' <SEP> 3.44 <SEP> 15 <SEP> hours- <SEP> - <SEP> - <SEP> -
 <tb> 51 <SEP> 94.0 <SEP>. <SEP> 17.2 <SEP> 100- <SEP> w <SEP> 7.50 <SEP> 8 <SEP> days <SEP> 1.18 <SEP> 4.80 <SEP> 6.39 <SEP> 8.8 <SEP> 27 <SEP> 23
 <tb>
 
 EMI75.7
 52,114 17.1 - 169 -. WC 4.00 5 days 1.50 1.43 8.00 8.16 - - 53 63 9.45 - 69.5 - W - tu, 70 16 hours 0.81 0, 94 11.10 6.1 40. 25
 EMI75.8
 
 <tb> 54 <SEP> 54.3 <SEP> 8.15 <SEP> - <SEP> 104.2 <SEP> .- <SEP> W <SEP> 4.72 <SEP> 16 <SEP> hours <SEP> 0.73 <SEP> 0.70 <SEP> 8.34 <SEP> 5.5 <SEP> 32 <SEP> 25.
 <tb>



  55 <SEP> 47.8 <SEP> 7.17 <SEP> - <SEP> 139.0 <SEP> - <SEP> W <SEP> 4.71 <SEP> 16 <SEP> hours <SEP> 0.63 <SEP> 0.72 <SEP> 5.57 <SEP> 4.6 <SEP> 39 <SEP> 25 <SEP>
 <tb>
 
 EMI75.9
 56 114 17.1 - 55.2 1.2 W 5.00 6 days 1r23 2.08 9.54 11 22 33 57 39.9 1.78 8 - 16.6 - W b, 38. 16 hours - - - .. ¯ ¯ 58 36.1, 2.51 a - 25.0 0.8 W 6.24 16 hours - - - .-- - -
 EMI75.10
 
 <tb> 59 <SEP> 43.5 <SEP> - <SEP> - <SEP> 30 <SEP> - <SEP> W <SEP> 7.00 <SEP> 16 <SEP> hours <SEP> - <SEP> - <SEP> - <SEP> - <SEP> - <SEP> -
 <tb>
 
 EMI75.11
 60 43.5 - '- 7.0 0319 W 6.31 16 hours - - - - - -
 EMI75.12
 
 <tb> @ <SEP> = <SEP> aluminum <SEP> atomized <SEP> substitute <SEP> on <SEP> nitride <SEP> of aluminum.
 <tb>
 

  <Desc / Clms Page number 76>

 



  TABLE II.
 EMI76.1
 



  #### '####' "" ###### "" '"Refractory composition
 EMI76.2
 
 <tb> Parties <SEP> of <SEP> material <SEP> refract-
 <tb> @ <SEP> shut up <SEP> by- <SEP> Composition
 <tb> Conditions <SEP> of <SEP> press <SEP> Properties <SEP> mechanical <SEP> tie <SEP> of <SEP> metal <SEP> Composition <SEP> of <SEP> the
 <tb>
 
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 DIe I:> <it! .c hase "meta liaue pie boLb.¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯. ###:

  ############### * "####### * n Tema Atmos- Resistance - Hardness' Observed density / TiN AIN'AL 0% W% C% others
 EMI76.4
 
 <tb> C <SEP> of <SEP> phere <SEP> tance <SEP> Rockwell <SEP> density <SEP> calculated ' <SEP> '' <SEP>
 <tb> main- <SEP> to <SEP> the <SEP> A
 <tb> tienruptu-
 <tb> (min) <SEP> re
 <tb> transverse
 <tb>
 
 EMI76.5
 45 l90Ck 6 N 2 9527 90.1 "'7.7 / 7.75 3s4 0.8 100 - 46 1750 5 N2 12341 90.2 8.23 / 8.35 - 2.10.6 - 97.9 2 , 1 - 47 1810 2 empty - 90.4 907/9, iz 2.1 0.5 - ¯i00 - 48 1800 1 empty 10 388 86.2 8th! 1 / 8.53 2.9 0.6 - 100. - - 49 1500 4 empty 10528 88.8 8.06 / 7.86 3.0 0.6 - 100 - - 50 1600 4 empty 11815 - 88.8 7, 96/8, OI.), 4 0.5 - 100 - 51 1800 2 empty 17413 90.6 8.49 / 8.69 2.9 - 0.6 100 -.

   - 52 1900 6 empty 9212 $ 91 0- 8.53 / 8.86 2.4 0.6'- 846 ¯ 15.4 wc / 'co 1800 empty 8918 91,, 3 8.65 / 8.86 2.4 0.6 84s6 - 15.4 wc / co
 EMI76.6
 
 <tb> 53 <SEP> 1850 <SEP> 4 <SEP> empty <SEP> 7280 <SEP> 87.8 <SEP> 7.60 / 7.97 <SEP> 3.1 <SEP> 0.8 <SEP> - <SEP> 100 <SEP> - <SEP> -
 <tb> 54 <SEP> 1850 <SEP> 4 <SEP> empty <SEP> 8659 <SEP> 86.0 <SEP> 8.99 / 9.43 <SEP> 1.8 <SEP> 0.4 <SEP> - <SEP> 100-
 <tb>
 
 EMI76.7
 55 1825 4 empty 11515 84.1 10.71 / 10.61 1 # 2 oye3 - 100 56 1780 5 empty - - 7.73 / 7.86 3.1 0.8 - 97.5 2.5 57 1700 4 empty 9562 89.0 7.97 / 8.03 3.7 Oe3 - 100 - -
 EMI76.8
 
 <tb> 1600 <SEP> 4 <SEP> empty <SEP> 9723 <SEP> 87.4 <SEP> 8.13 / 8.05 <SEP> 3.5 <SEP> 0.5 <SEP> - <SEP> 98.1 <SEP> 1.9 <SEP>
 <tb> 59 <SEP> 1750 <SEP> 4 <SEP> empty <SEP> 8148 <SEP> 88.4 <SEP> 8.50 / 8.56 <SEP> 3.4 <SEP> - <SEP> - <SEP> 100 <SEP> - <SEP>
 <tb> 60 <SEP> 1750 <SEP> 4 <SEP> empty <SEP> 6482 <SEP> 88.2 <SEP> - <SEP> 6,

  0 <SEP> - <SEP> - <SEP> 97.2 <SEP> 2.8 <SEP> -
 <tb>
 

  <Desc / Clms Page number 77>

 
EXAMPLE 46.



   A compression tool is made as described in Example 1 from the pressed ball shown in Example 46 in Tables I and II. This cutting tool is tested on 4340 grade steel at a surface speed of 152 meters / minute, using a feed of 0.254mm and a depth of cut of 1.27mm. The tool is working satisfactorily. After 3 minutes without failure, it shows an average bit wear of 101.6 microns and a crater depth of only 25.4 microns.

   At a speed of 61 surface meters per minute, used a cutting depth of 1.587 mm and a feed of
0.762mm, this tool shows no bit wear and no crater wear, when running for 1 minute. In another test at a surface speed of 91.2 meters per minute, again using a depth of cut d @ 1.587mm and a feed of 0.508mm, this cutting tip runs for 30 minutes without breaking. , fault, giving an excellent finish to the workpiece and it exhibits a bit wear of only 101.6 microns and a crater depth of only 25.4 microns.



    EXAMPLE 47.



   A molybdenum cuvette is charged with 73 g of a colloidal titanium nitride active in an inert atmosphere and placed in a tubular ceramic furnace.



   This material is calcined for 16 hours at 1200 C in an ammonia atmosphere. The oven is opened to the air and 69 g of a crumbly brown powder are recovered. This material has the following composition: 2.16% oxygen, 0.04% carbon, 7.1% titanium, and 20.55% nitrogen. This powder has a specific surface area of 7.3 m2 / g, which corresponds to a particle size of 155 millimicrons, X-ray examination

  <Desc / Clms Page number 78>

 reveals that the only phase present consists of titanium nitride.

   A refractory dispersion is prepared from this titanium nitride, in combination with aluminum nitride and tungsten, like Example 45, but using operating conditions given in Tables 1 and II for Example 47. L A cutting tool made from this material performs excellently when used to cut 4340 steel. Has a surface speed greater than 274 surface meters / minute and a depth of cut of 1.27 mm and a feed of 0.254 mm, this tool exhibits a bit wear of 101.6 microns and a crater depth of 50.8 microns, when operated for 3 minutes. This tool operates without failure and produces an excellent finish on the workpiece.

   On 4340 steel, at a surface speed per minute of 132 meters, using a cutting depth of
3.175 mm and a feed rate of 0.762 mra, this tool exhibits a cutting edge wear of only 50.8 microns and no measurable crater wear after 1 minute of operation. This cutting tool is used to remove the beards from a new log made of 4340 steel, and cuts a total length of '91.44 cm with' cutting edge wear.
Only 101.6 microns and a crater depth of 63.5 microns, giving an excellent finish to the workpiece.



   The conditions are here. of 97 surface meters / minute, a speed of 0.508 mm and a cutting depth of 3.175 mm.

  <Desc / Clms Page number 79>

 



   EXAMPLE 48.



   A cutting tool was prepared from the heat treated bead prepared for Example 48 as shown in Tables 1 and 2. ' This cutting tool experienced on cast iron has a surface speed of 152 meters / minute, using a feed of 0.508 mm and a depth of cut of.
1.27mm, cuts for 91 minutes without failure.



   Also on cast iron and at a surface speed of
231 m / minute, with the same cutting depth and feed conditions, this tool cuts for 43 minutes without failure.



   Another pressed dispersion of this same powder gave a cutting tool with a life of 43 minutes and 30 seconds on 4340 steel at a surface speed of 121.6. m / minute, a feed of 0.508 mm and a depth of 1.587 mm. The same tip is used to make a milling on malleable cast iron at a surface speed of about 60m per minute, using a depth of cut of 2.54mm and a feed of 1.016mm per tooth and cut one, total of 58.736 cm before failure occurs.



    EXAMPLE 49.



   Using a commercial titanium nitride, a hot-pressed refractory dispersion is prepared as in Example 45, under the same conditions as Example 49 (see Tables 1 and 2). A cutting tool is prepared from this material, which tool operates excellently on steel at a surface speed of 121.6 m per minute - and shows low wear and long life. .

  <Desc / Clms Page number 80>

 



    EXAMPLE 50.



   A cutting tool is made as described in Example 45, using a finely divided titanium nitride: A hard and strong cutting tool is obtained which operates satisfactorily on steel at a surface speed of. 91:, 2 m / minute, with a long operating time or life.



    EXAMPLE 51.



   A high speed cutting tool is prepared from the hot pressed refractory dispersion shown for Example 51 in the table. This tool is prepared according to the method of Example 45 and it constitutes a refractory cutting tool which is stable against thermal shocks. This cutting tool cuts for 9 minutes and 12 seconds on 4340 steel. Brinnel hardness 203, when experimenting at a surface speed of 167 m / minute, using a feed or lateral displacement of 0.508 mm and a depth of cut of 1.587 mm.



    EXAMPLE 52.



   The first cutting tool of Example 52 in Tables 1 and 2 was tested on 4340 steel and performed excellently, as shown by the following test:
At a surface speed of 258 meters per minute, using a depth of cut of 1.27 mm and a feed of 0.254 mm, this tool runs for 3 minutes without slipping and exhibits a bit wear of 1.016. mm only and a crater depth of only 38.1 microns.



   At a speed of 112.5 m at surface per minute, using a cutting depth of 3.175 mm and a feed rate of 0.508 mm, this tool will only run for 1 minute with a cutting edge wear of 25.4 microns only and no wear by formation

  <Desc / Clms Page number 81>

      of measurable crater.

   Also at a surface speed of
112.5 meters / minute, with. A cutting depth of 3.175 mm and a feed rate of 0.76 @ mm, this tool performs excellently for 15 minutes and 27 seconds,
The second, the cutting edge, prepared from the same orderly dispersion, with the properties shown in the tables, also exhibits excellent cutting tip properties when experienced on steel.
4340 at a surface speed of 304 meters per minute. This tool operates satisfactorily for 3 minutes, with a bit wear of only 76.2 microns and a crater depth of 0.1397 mm.

   At a surface speed of 99 meters / minute, this tool cuts satisfactorily for 10 minutes with a cutting wear of only 50.6 microns and a crater depth of only 6.35 microns. of course. In a milling test on malleable cast iron. this cutting point exhibits a toughness exceeding that of other commercial cutting points used on this type of material. This tool is tested at a speed of 78 @etres. surface / minute, a cutting depth of 2.54 mm, with feeds of 0.208 mm, 0.432 mm and 0.953 mm. In all. under these conditions, the tool operates satisfactorily without failure.



   EXAMPLE 53.



   The hot-pressed ball shown for the example
53 in the table is used to make a cutting tool and is tested on 4340 steel of hardness
Brinnell greater than 307. This tool, at an over- "face speed of 112.5 meters / minute, with a cutting depth of 1.587 mm and a feed of 0.508 mm, has an existence of
66 minutes and 30 seconds. At surface speed

  <Desc / Clms Page number 82>

 of 161 meters / minute, this tool has a life of 18 minutes.



   EXAMPLE 54.



   A refractory dispersion is prepared as in Example 45 and under the conditions shown in Tables 1 and II for Example 54. This material constitutes a strong and hard cutting tool which has a life of.
23 minutes and 30 seconds on 4340 steel at a speed of 121.6 surface meters / minute.



   EXAMPLE 55.



   An extremely hard and solid refractory dispersion shown for Example 55 in Tables I and II conformed to a cutting tool for 6t steel tested on 4340 steel at a surface speed of 125 meters / minute, in using a cut depth of 1.587mm and a feed of 0.508mm. This tool will perform satisfactorily for more than 9 minutes on 4340 steel.



   EXAMPLES 56 '- 60 ..



   The following five examples are prepared as in Example 45P except that after the grinding period indicated in the table for the suspension of titanium nitride and luminium nitride, finely tungsten. divided is added to the ball mill and dispersed in the slurry by additional grinding for two hours.



   EXAMPLE 56.



   A hard refractory cutting tool intended for steel is prepared as in Example 45 from the refractory dispersion shown for Example 56 in the Tables. In the machining tests on high grade steel - bed 4340, at a surface speed of 304 meters / minute, using a cutting depth of 1.27 mm and a feed of 0.254 mm, this refractory cutting tool has a

  <Desc / Clms Page number 83>

 101.6 micron bit wear and 38.10 micron crater depth after 3 minutes cut without failure.

   On the same steel at a speed of 109 surface meters per minute $ with a cut depth of 3.175 mm and a feed of 0.762 mm, this tool shows bit wear of only 25.4 microns and no wear by measurable crater formation after 1 minute of operation.



   EXAMPLE 57.



   A hot-pressed bead was prepared in the same manner as that of Example 45, with the exceptions mentioned above. The preparation process and the physical properties are given in Tables I and II.



   A cutting tool made from this material makes an excellent cutting tool on steel and cast iron when used at a feed rate of 91.2 to.
152.0 surface meters / minute, a depth of cut of 1.587mm and a feed of 0.254mm.



    EXAMPLE 58.



   This composition, shown in Tables I and
It is prepared as described above, being an excellent cutting tool on cast iron, at a high speed. face of 121.6 meters / minute, with a cutting depth of
3.175 mm and a lead of 0.508 mm.



    EXAMPLE 59.



   A cutting tool is made as described in Example 45 from the pressed refractory dispersion shown for Example 59 in Tables I and II. This cutting tool exhibits excellent wear resistance when not used to cut 4340 steel at a speed of 91.2 surface meters / minute with a depth of

  <Desc / Clms Page number 84>

 cutting of 3.175 mm and a feed of 0.254 mm.



   EXAMPLE 60.



   The hot pressed refractory dispersion shown in Tables I and II for Example 60 is used to make a cutting tip for steel. This tool exhibits exceptionally wear resistance and thermal shock stability and cuts steels at speeds of up to 152 surface meters per minute with good run time.



   EXAMPLE 61 ..



   A ball mill is charged with 92 grams of commercial vanadium nitride with a caliber of 0.044 mm which is ground for 5 days in a steel mill. with 6000 g of tungsten elements and 150 g of an oil. , hydrocarbon type. To this ground suspension of finely divided vanadium nitride, 77.8 g of a tungsten powder previously ground in a ball mill is added.



   These substances are then mixed for 2 hours by grinding. The suspension obtained is then placed in a resin boiler and dried in vacuo. The dried powder is then discharged into an inert atmosphere and sieved through a 0.210 mm sieve. A hantillon of this powder dispersion is used to shelter a hot pressed log and cutting tool as rewritten in Example 45.



   The samples of ecanic experimentation give the following results: resistance to transverse rupture
7854 kg / cm2, Rockwell A hardness: 86.4 \ and density: 9.18 g / cm3.



   This density constitutes approximately 98% of the expected density for this material, which has a nominal conposition of 3 parts by volume of vanadium nitride per part by volume of metallic tungsten.

  <Desc / Clms Page number 85>

 



   This sample constitutes a good quality cutting tool for steel, which shows good wear resistance and thermal shock resistance.



   EXAMPLE 62.



   36 g of a colloidal corundum powder having a specific surface area of 29 m2 / g and an average crie- tallites size of about 40 millimicrons are screed in a 1.9 liter steel grinder with 40 g of the @ The titanium nitride powder of Example 1, 6 g of the powdered aluminum nitride of Example 21 and 93 g of the metallic tungsten fiber of Example 23.



   345 ml of a high boiling point hydrocarbon type oil having a flash point of 8 C as well as 6.622 g of metallic tungsten rods or rods are also charged to the mill. The metallic tungsten elements are in the form of small cylinders, 6.35 mm in diameter and 6.35 mm in length. The crusher is charged and closed in an atmosphere of nitrogen to prevent oxidation of the material during the grinding operation, the tower crusher. ne on rubber lined rollers for a period of 5 days at 90 revolutions / minute.



   The mill is connected to a vacuum system and the contents are vacuum dried by heating the exterior of the mill with steam. The obtained finely divided powder dispersion of alumina, nitrides and metal is recovered from the mill and separated from the tungsten elements. These operations are carried out in a nitrogen atmosphere. ,

  <Desc / Clms Page number 86>

 
The tungsten elements Ierdent 29 g during the 5-day grinding, This quantity, adulated to the 93 g of the tungsten metallic powder init. alement cracked in the mill, gives a total of 122 g of metallic tungsten incorporated in the composition.



   Chemical analysis of the powdered dispersion shows that it contains approximately 18% Al2O3, 20% TiN, 3% AlN, and 59% W. The specific surface area is 11 µ2 / g.



   23 g of this powder are placed in a carbon mold, in an inert atmosphere, using metal molybdenum discs as a separator. The temperature is raised to 1775 C, under vacuum, and after 5 minutes a pressure of 280 kg / cm2 is imposed. The temperature and pressure are maintained for 2.5 minutes. The pressure is then removed, the sample is cooled and then removed from the oven.



   The refractory compact body obtained according to the invention is cut with a diamond so as to obtain samples for testing the transverse breaking strength, the impact resistance, the hardness on the Rockwell A scale and the ' .ensile. A cut is made as a carry-over piece of a metal cutting tool.



   The transverse breaking strength is 8750 kg / cm2, its impact resistance is 1 @ 68 kg-m / cm2 and its hardness
Rockwell A is 91.8. The density is 8.12 g / cm3 which represents more than 99% of the theoretical flow rate which was expected for these compositions, relative to the specific volumes of the initial constituents.



   . A metallographic examination of this compact body shows that the alumina, the tungsten and the nitride phase are present in a square region of 10 mirons apart, and,

  <Desc / Clms Page number 87>

   in 10 100 square micron genus regions examined, all showed these same structural features. The compacts contain 1.5 parts of aluminum, 1.2 parts of titanium nitride and 0.3 part of aluminum nitride per part of tungsten.



   A cutting tool insert of this composition is tested on 4340 steel, using a cutting depth of 3.175 mm, a surface speed of '
91.2 mm / minute and a damage of 0.762 mm per revolution.



   After 1 minute of cutting, the wear of the cutting edge observed is 50.8 microns and the crater depth is 12.7 microns.



   The cutting tool insert according to the invention can cut 4340 steel even at a speed of
274 surface meters / minute, with a cutting depth of 1.27 mm and a feed of 0.254 mm per revolution. In this case, the average bit wear is 0.1524 mm in three minutes and the crater depth is 25.4 microns.



   Another cutting tool of this composition is used as a single tooth in a milling head during conventional milling to cut hardened 4340 grade steel of Brinnell hardness 330 with a profile. - cutting depth of 1.27 mm, feed rate of 0.1778 mm per tooth and a speed of 144 surface meters per minute. The average bit wear is only 0.3048 mm and no tool failure or swelling ensues, even after cutting 6.10 meters of metal, the experiment being stopped at this point. point. Finished. of the metal surface at this point is still very good.

   A wear-resistant commercial * cutting tool made of modified tungsten carbide and tested titanium carbide and tantalum carbide

  <Desc / Clms Page number 88>

 under the same conditions cut only 122 cm of metal, the test being stopped at this point due to deterioration in the finish of the metal surface. The average wear of the cutting edge of commercial steel is then 0.6096 mm.



   Another cutting tool of this composition is used as a single tooth in a milling head to cut malleable cast iron at a depth. 0.254mm cutting depth, 1.016mm feed per tooth and 60 surface meters per minute. No crater wear or cutting edge wear was observed as well as no tool failure even after a 168 cm cut of metal, so the experiment was stopped.



   EXAMPLE 63.



   51 g of the alumina powder of Example 62, 55 g of titanium nitride powder of Example 1, 8 g of aluminum nitride powder of Example 23 and 81 g of molybdenum powder metal of Example 8 are placed in a ball mill with 350 milliliters of hydrocarbon type oil and 4883 g of metal molybdenum rods or rods. The grinding is carried out as described in Example 62 as well as the recovery of the final product. Molybdenum elements show no weight loss during the grinding operation.



   The intimate dispersion obtained according to the invention has, according to the chemical analysis carried out, the following composition: 25.5% by weight of Al2O3, 27.5% of TiN, 4%
AlN and 43% Mo,

  <Desc / Clms Page number 89>

   17 g of this powder are folded into a die
 EMI89.1
 of carbon and pres, 4a with the ins% allat ..> n described in llextm- # 62, using the same pressure conditions at
 EMI89.2
 1725 * 0 * The refractory dispersicn obtained according to the invention has a transverse breaking strength of 8750 kg / cm2, an impact strength of 14.56 kg-m / cm2 and a du-. Rockwell A retainer of 91.8.

   The density is 5.86 g / cm3, which represents 100% of the theoretical density expected for this composition.



   Metallographic examination of the refractory dispersion shows interdispersion of almine, molybdenum and nitrides. The average size of crystallites determined by X-rays of alumina is 420 millimicrons, that of molybdenum is 71 millimicrons and that of titanium nitride is 100 millimicrons. Metallographic examination shows that all of the constituents are present within a 10 micron square region and that, of 10 100 square micron regions examined, 9 show these same structural characteristics. The dispersion consists of about 1.5 parts of alumina, 1.2 parts of TiN and 0.3 part of AlN per part of molybdenum.



   The cutting tool insert according to the invention, when used to cut 4340 steel at a speed of 274 surface meters per minute, with a depth. cutting thickness of 1.270 mm and feed of 0.254 mm per revolution, shows cutting edge wear of 0.1524 mm in
3 minutes and a crater depth of 25.4 microns,

  <Desc / Clms Page number 90>

 
EXAMPLE 64
2000 g of a -0.044 mm caliber tabular alpha alumina, commercially available as a grade T-61 alumina powder, sranx loaded into a steel mill half-filled with iron balls. 'steel.



  200 g of water are added and the mill is rotated at 35 revolutions / minute for 144 hours, After grinding, the alumina is recovered, treated with a mixture of hydrochloric acid and nitric acid to remove iron, washed with water and dried.



   Alumina powder. ground has a specific surface area of about 9 m2 / g and an average particle size of about 2 microns.



     6 g of this alumina powder, 40 g of the titanium nitride powder of Example 1 and 6 g of the aluminum nitride powder of Example 21 are placed in a ball mill. together with 5837 g of the tungsten elements used in Example 62 and about 200 ml of hydrocarbon type oil. Grinding is carried out for 5 days as described in Example 62 and the recovery of the product is carried out likewise.



   The finely divided powder dispersion obtained is recovered and separated from the tungsten elements. These operations are carried out in a nitrogen atmosphere.



   The tungsten elements lose 48 g when grinding for 5. days.



     70 g of tungsten metal powder of Example 23 and all of the powder dispersion previously recovered from the sant mill placed in a mill with the same amount of tungsten elements and hydrocarbon type oil used above. Grinding is carried out for 2 hours,

  <Desc / Clms Page number 91>

 as described in Example 62 and recovery of the product.



     The same is done. The resulting finely divided powder dispersion of alumina, mixed nitrides and tungsten is recovered from the mill and separated from the tungsten elements. do in an inert atmosphere. The tungsten elements do not lose any weight during the 3 hour grinding operation.



   23 grams of the product are placed in a graphite mold in an inert atmosphere. The temperature is @. raised to 1775 C under vacuum and a pressure of 280 kg / cm2 is imposed after 5 minutes. The temperature and pressure are maintained for 3 minutes, the pressure is then removed, the sample is cooled and then removed from the oven.



   The compact refractory product obtained is substantially dense, very strong and has excellent impact resistance. This refractory compact body can be an excellent cutting tool for steel. It contains 1.5 part of aluminum, 1.2 part of TiN and 0.3 part of AlN per part of tungsten.



   A cutting insert of this composition is used as a single tooth in a milling head to cut hardened steel, grade 4340, Brinnell hardness 330, with a depth of cut of 1.27mm, . a feed rate of 0.1778 mm per tooth and a speed of about 144 meters on the surface per minute. The average cutting edge wear was only 0.508 mm after cutting 244 cm of metal, the experiment being stopped at this point.



    EXAMPLE 65. '
27 g of the alumina powder of Example 62 and
35.7 g of the titanium nitride powder of the same example are placed in a ball mill, together with the same amount of tungsten elements and hydrocarbon type oil, as described in example. 62.

  <Desc / Clms Page number 92>

      



   The grinding is carried out in the same way as described in Example 62 and the recovery of the final product is done in the same way. The elements of tungs @ only lose 25 g during the. 5-day grinding,
62.2 g of the metallic tungene powder of Example 23 and all of the sewing dispersion previously recovered from the mill are placed in a steel mill with the same amount of tungene and metal elements. hydrocarbon type oil used above.

   The grinding is carried out for hours as described in Example 62 and the recovery of the product is carried out likewise. The obtained finely divided powder dispersion of alumina, titanium nitride and tungsten. is recovered from the mill and stripped of the tungsten elements in an inert atmosphere. There is no weight loss from the tungsten elements during engagement.



   23 g of this powder are loaded into a graphite mule and heated to 1680 C. After 5 minutes at this temperature, a pressure of 280 kg / cm2 is applied which is maintained for 1 minute The pressure is then released, the sample is cooled and is then removed from the oven.



     The compact refractory body obtained is substantially dense, solid, very hard and is useful for carrying out a treatment for metals rotating at high speeds, under conditions in which commercial tools do not give satisfaction. This body contains 1.5 parts. of alumina and 1.5 parts of TiN per part of tungsten.



   EXAMPLE 66.



   24 g of the alumina powder of Example 62, 14.1 g of the titanium nitride powder of Example 1, and 2.11 g of the aluminum nitride powder of Example 21 are placed. - cés in a ball mill, together with the same portion '

  <Desc / Clms Page number 93>

 tungsten elements and hydrocarbon-type oil as described in Example 62. Grinding is carried out for 5 days as described in Example 62 and the product is recovered in the same way. . The tungsten elements do not lose. 22 g leaning this grinding.



     The powdered dispersion obtained is charged again in a ball mill together with 37.75 g of metallic t @ngsten powder of Example 23. The grinding for 2 days, the drying and the recovery of the product are identical to those. which were described in Example 65. The tungsten elements show no weight loss during this grinding operation.



   23 g of this product are placed in a carbon mold and heated under vacuum at 1650 C. After 5 minutes a pressure of 280 kg / cm2 is applied which is kept little. in 1 minute..The pressure is then released, the sample is cooled and is then removed from the oven. The refractory compact body obtained is substantially dense, very hard and very strong.

   It contains 1.95 part of alumina, 0.84 part of TiN and 0.21 part of AIN per part of metallic tungsten. This body is useful for rotating metals under high speed conditions with advances where commercial ceramic tools do not give satisfaction.



    EXAMPLE 67.



   60 g of the alumina powder of Example 62,
16.34 g of the titanium nitride of Example 1 and 2.44 g of the aluminum nitride of Example 21 are placed in a ball mill with 200 ml of hydrocarbon oil and
5981 g of metallic tungsten sticks or rods,

  <Desc / Clms Page number 94>

      
The grinding is carried out as described in the example
62 and the product is recovered in the same way. The tungsten elements lose 33 g during the 5 day grinding iteration.



   The powder dispersion recovered from the grinding and 87 g of the metal lungsten powder of Example 23 are placed in a ball mill with the same amount of tungsten elements and hydrocarbon oil as in. the previous grinding operation, The grinding is carried out for 2 hours as described in Example 62, as well as the recovery of the product. The resulting finely divided powder dispersion of alumina, mixed nitrides and tungsten in an inert atmosphere. There is no loss of weight of the tungsten elements during grinding.



   23 g of this powder are loaded into a graphite mold and heated to 1730 C. After 5 minutes at this temperature, a pressure of 280 kg / cm2 is applied which is maintained for 1 minute. The pressure is then released, The sample is cooled and then removed from the oven.



   The obtained refractory compact body is substantially dense * $ has a transverse tensile strength of 8890 kg / cm2 and an impact strength of 5.2 kg-m / cm2.



   It contains 2.4 parts of umine, 0.48 part of TiN and
0.12 part of AlN per part of tungsten. It shows a. remarkable utility% Or $ forms the one tool for cutting metals.

  <Desc / Clms Page number 95>

 
 EMI95.1
 



  'j,,' 7 '.;! (".... ff, I;' EXAMPLE 68." '- -' '. 1). "" (. "$ Il <", /" 114 g d! titanium nitride, 17.1 g of nitride f <) ,,, µj + 0/9, 19 dta.um3, n.um oudr ma1 bdns 3, nemant. ':; ';, I a of aluminum and 5C of molybdenum powder finemon% # 1-] 4' () "'referred to are loaded into a steel ball mill and,: 1",. / ". It" ', 1.} ..,'; f ground for 5 days with 3.96 kg of elementa of molys- <, 1 (é "" \;. 'J .. f. T 1.. Dene. This suspension is elaborated and prepared pure s' = 1 ,.' '. Pressing; (1'. The is pressed retort to l 'example 4S have this' \ -.' f;:; "'' '?; Íi; ::,' '!' \: ;; f'l, i" I; .... is only 1s powder is held at 1835 "C for 5 minutes before pressure is applied.

   This d ", y:., 'Y'" '"t ;.'. <'reaction persion "" e obtained has a tensile strength,:, 1).' 7;:. ' / transverse of 11.907 k / om, a Rockwell A hardness of :: /:;.,;.: '' ':: z8 and a density of 6.05 g / cm3. Theoretical density '' /. '. planned for this composition is 6.0 g / cm3 The dispexr,. , y ',,, s consists of about ,, t partios volume. The ion consists of about 34 parts by volume of ni "l." . ' titanium tride and about 0.8 part by volume of nitt->;: 5 re aluminum per part by volume of molybdenum. '> :. a;., tJ, j?' ';;., This substance is an excellent tool when ': "vt;',. which can be used to machine 4340 steel. At a speed of. 1: ..; ' , 4 .y.

   N, surface of 304 meters / minute, with an advance of 0.254 ama ... v Fe. yt ', and a cutting depth of i, 27 mm, this tool cuts pen-. .. "for 3 minutes without failure and shows edge wear ./gl¯,j ,, cutting 101.6 microns only and depth <1. OI "QI'If ':': 't'; 1" e of 25.4 miorona ..ulemeSu.r of 3.'f, Q: Ltr 4340 to uno. bzz surface speed da $ 6 mittra, / m1nute, with an avanoe 4 # y, ', "5 .. 0, 76 mm and a throat depth of 3.17S mm, this bu% # 1'" 1 '/ , 1,]): cuts without failure for 1 minute, showing an "É J 1µ,. Tr., ', 1 (1. Cutting edge wear of 25, µ microns only and a p" o ","' '.;, 1, founder crater who doesn * t pao moaUrabÀa, flela oon # ti% ùe' o) Ç? crater which is not measurable This constitutes 1 \ 1 ..;. "lament a good cutting tool for milling on cast iron,.

   Y, '' S, p4A.3'a.: 'Y malleable to 27.94 cm without failure, wear of, \ ,. i') '7: 2'. dY
 EMI95.2
 cutting edge being only 50.8 microns, when experienced
 EMI95.3
 : "}" '- /. \

  <Desc / Clms Page number 96>

 at a speed of 106 meters in area @ ar minute, with a cutting depth of 2.54 mm and a feed rate of
0.762 mm per tooth.



    CLAIMS, 1.- Refractory composition comprising a metal selected from molybdenum, tungsten, chromium, rhenium and their alloys, with which is interdispersed or mutually dispersed a nitride selected from titanium nitride, nitride 'of zirconium, (tantalum nitride, hafnium nitride, aluminum nitride, vanadium nitride, niobium nitride, and mixtures thereof.



     2.- refractory composition according to claim 1, in which are dispersed: homogeneously 1 to
99 parts by volume per part by volume denoted distinct particles of the nitride.



     3, - Refractory composition according to claim-% ion 1 or 2, in which are homogeneously dispersed
1.5 to 19 parts by volume per part by volume of metal of distinct particles of the nitride.



   4. A refractory composition according to one or other of claims 1 to 3, characterized in that the metal and the nitride have an average particle size of less than 50 microns.



   5.- refractory composition according to one or the other of claims 1 to 4, characterized in that the metal and the nitride have an average particle size less than
10 microns.

** ATTENTION ** end of DESC field can contain start of CLMS **.

 

Claims (1)

6.- A refractory composition according to one or the other of claims 1 to 5 @ comprising a metal selected from molybdenum, tungsten, chromium, 'rhenium, their alloys with each other, and their alloys with minor amounts ... <Desc / Clms Page number 97> EMI97.1 res of a metal chosen from among ter # titanium and, csn.ur., in aque'sat from '1 part to 99 parts by volume' per part by volume of metal of a particular nitride ch plligt among titanium nitride, zirconium nitride, leni @ ride EMI97.2 tantalum, hafnium nitride, aluminum nitrate, vanadiolate nitride, niobium nitride and their m4le.ige; 7.- The refractory composition according to one or more of claims 1 to 6, characterized in that the compound is replaced by amounts up to 95% by volume of a compound. EMI97.3 particulate matter selected from bary.à.umy nitride, thorium nitride, cerium nitride, boron nitride, uranium nitride, titanium monoboride, zirconium monoboride, titanium carbide , zirconium carbide, EMI97.4 tantalum carbide, niobiuni carbide, magnesium, zirconium oxide, alumina, thorium oxide and their mixtures with each other. 8.- refractory composition according to one or other of claims 1 to 7, characterized in that the dispersion has a density of more than 95% of its theoretical density,. 9.- refractory composition according to one or the other of claims 1 to 8, characterized in that the dispersion at a density of more than 98% de.sa theoretical density, EMI97.5 10.- refractory composition according to either of claims 1 to 9, characterized in that the metal is in the form of a continuous matrix. 11.- Refractory composition according to one or the other EMI97.6 tre of claims 1 to 10, characterized in that the me, -; tal is molybdenum * <Desc / Clms Page number 98> EMI98.1 12, '* Refractory composition according to one or. The other of claims 1 to zij, aax; ctdt $ s if the material is tungsten. 13. "A composition in the form of ,, ordre comprising a metal selected from molybdenum, tungs @ ene, chromium, EMI98.2 rhenium and their alloys with which is, re-dispersed a nitride selected from lo titanium nitride, tirconima nitride, tantalum nitride, nitride! a'n3.uzvrr,, enaru re cfa, m, n, um, vanadium nitride, niobium nitride their mixtures. EMI98.3 ... 14.- Powder composition according to the claim :. No. 13, characterized in that 1 to 99 parts by volume of distinct particles of nitride per part by volume of metal are homogeneously dispersed therein. EMI98.4 .5. Powder composition according to Claim, 13 or 14, characterized in that 1.5 to 19 parts by volume distinct disarticles of nitride per part by volume of metal are homogeneously dispersed therein. 16.- A powder composition according to any one of claims 13 to 15, characterized in that the metal and; nitride have an average particle size less than 50 microns. 17.- Compositio @ powder according to one or the other EMI98.5 of claims 13 to 16, characterized in that .e ,, dta. and the nitride have an average paz.cu.a, r size less than 10 microns. 18.- Sewing composition according to any one of claims 13 to 17, comprising a metal selected from molybdenum, tungsten, chromium, rhenium, their alloys with each other and their alloys with minor amountsa of a metal selected from iron, titanium, and zirconium, in which are dispersed from part to 99 parts by volume per part by volume of metal of a particulate nitride <Desc / Clms Page number 99> chosen from titanium nitride, zirconium nitride, cantaloupe nitride, hafnium nitride, aluminum nitride, vanadium nitride, niobium nitride and mixtures thereof ..- 19 .- * Powder composition according to one or the other <, of claims 13 to 18, characterized in that the nitride is replaced by amounts up to 95% in wlume of a particulate compound selected among beryllium nitride, thorium nitride, cerium nitride, boron nitride, uranium nitride, titanium monoboride, zirconium monoboride, carbide of titanium, zirconia carbide, tantalum carbide, niobium carbide, magnesium, zirconium oxide, alumina, thorium oxide, and mixtures thereof with each other. 20 ,, - 'Powdered composition according to one or the other of claims 13 to 19, characterized in that the metal is molybdenum, 21. Powder composition according to one or the other of claims 13 to 19, characterized in that the metal is tungsten. 22.- A method of forming a refractory composition, characterized in that a composition comprising a metal chosen from molybdenum, tungsten, chromium, rhenium and their alloys with which is interdispersed a nitride chosen from among titanium nitride, zirconia nitride, tantalum nitride, hafnium nitride, aluminum nitride, vanadium nitride, niobium nitride and mixtures thereof is compacted and heated. 23. A method according to claim 22, characterized in that the pressure is 35 to 420 kg / cm2. <Desc / Clms Page number 100> 24.- Method according to claim 22 or 23, characterized in that the temperature is from 1600 C to 2200 C. EMI100.1 25- A method to any of claims 22.4 24s characterized -n that the heating is carried out for a period of 5 seconds to 30 minutes. 26.- A method according to either of claims 22 to 25, characterized in that the heating and pressing are carried out under via; or in an inert atmosphere. EMI100.2 2? .- Process according to ltur. to the other of claims 22 to 26, characterized in that the composition is in powder form. 28.- Process according to one or the other of the claims EMI100.3 cations.:22 to 27, characterized in that the; onstituantl an average part.uaire caliber less than 50 microns. 29.- 'x, ddd according to one or the other of the resales 22 to 28, characterized in that the constituents have an average size of less than 10 beakers. 30.-. Procedure according to one or the other of the claims EMI100.4 cations 22 to 29, characterized in that a minor amount of iron, titanium or rconium is present. 31, - 'A method su @ ant either of claims 22 to 30, characterized in that the nitride is replaced. EMI100.5 o6 by amounts of up to 95% in y, uzr.a of a com-. selected from among \ <9 beryllium nitride, thorium nitride, erium nitride, boron nitride, uranium nitride, titanium monoboru @, monobide, zirconium, titanium carbide , e zirconium carbide, EMI100.6 tantalum carbide, carbide. ' obium, agnsia, zirconium oxide, alumina, Itoxyu, thorimn and their mixtures with each other. <Desc / Clms Page number 101> 32, - P @ océdé according to one or the other of claims 22 to 31 characterized in that the nitride is prepaid by reducing u @ hydride of titanium, zirconium, tantalum, * vanadium, niobium or hafnium to a particle size of less than 1 micron by contacting the powder with a reducing nitrogen atmosphere for a period of about 1 to @ hours at a temperature of about 800 to 1000 C. maintaining this atmosphere while increasing the temperature from approximately 1000 to 1100 C and maintaining this temperature for a period of approximately 1 to 16 hours, while still maintaining this atmosphere, increasing the temperature from 1200 to 1300 C and maintaining this temperature until nitrogen absorption ceases and recovering the refractory colloidal nitrides. 33. - A refractory composition according to one oul'autre of claims 1 to 21, we form a neck @ or cutting edge of a cutting tool,