US3565643A - Alumina - metalline compositions bonded with aluminide and titanide intermetallics - Google Patents

Alumina - metalline compositions bonded with aluminide and titanide intermetallics Download PDF

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US3565643A
US3565643A US803558A US3565643DA US3565643A US 3565643 A US3565643 A US 3565643A US 803558 A US803558 A US 803558A US 3565643D A US3565643D A US 3565643DA US 3565643 A US3565643 A US 3565643A
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aluminide
alumina
compositions
volume percent
carbide
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Horacio E Bergna
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EIDP Inc
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EI Du Pont de Nemours and Co
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
    • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
    • B23B27/148—Composition of the cutting inserts
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C04B35/111—Fine ceramics
    • C04B35/117—Composites
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/71—Ceramic products containing macroscopic reinforcing agents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors

Definitions

  • Aluminum oxide cutting tips are well known. Such tips possess advantages of extreme hardness and wearresistance as well as superior hot-bending strength. They are resistant to erosion and show little 'welding or diffusion between the chips and the tip. They are also oxidation resistant. However, these advantages are largely offset by the brittleness and lack of toughness of ceramic tips and a marked tendency toward stress, cracks, and eruptions.
  • compositions of alumina and certain carbides and nitrides bonded with an intermetallic are useful for making cutting tips having unusual properties. These compositions can be used to produce a cutting tip with an unusual combination of hardness and strength and one which is very resistant to wear and thermal shock.
  • dense compositions of this invention are useful as oxidation-resistant and chemical-resistant materials of construction.
  • This invention is directed to dense compositions having an average grain size smaller than 10 microns and composed of two interpenetrating three-dimensional networks; one network consisting essentially of alumina and the other network consisting essentially of a metalline selected from titanium carbide,
  • tantalum nitride and mixtures thereof;
  • nickel titanide nickel titanide, tungsten aluminide, molybdenum aluminide, niobium aluminide, tantalum aluminide titanium aluminide, zirconium aluminide, and mixtures thereof;
  • the alumina being present in an amount ranging from 20 to volume percent; the metalline being present in an amount ranging from 10' to 78 volume percent; and the intermetallic being present in an amount ranging from 2 to 30 volume percent, with the limitation that the volume percent of the metalline must not be less than the volume percent of the intermetallic.
  • compositions of this invention demonstrate exceptional advantages over similar compositions consisting of closely related compounds and over compositions of these same compounds in different amounts.
  • compositions of this invention are useful in cutting and milling ferrous alloys even at very high cutting speeds.
  • the figure is a graphical representation of the amounts of the components embraced within the compositional limits of this invention.
  • Area A is that area in 'which the compositional ratios are within the limits of this invention.
  • Area B is that area in which the compositional ratios are within the preferred limits of this invention, and
  • Area C is that area in which the compositional ratios are most preferred. Percentages shown on the graph are volume percents.
  • the refractory compositionspf this invention consist essentially of alumina; a metalline; and an intermetallic.
  • (a) Alumina The alumina is present in the compositions of this invention in amounts ranging from 20 to 80 volume percent. The need for at least 20 percent alumina is based on the desire to have the alumina present as a continuous phase. Amounts of alumina below 20 percent are less satisfactory because at these low levels the alumina phase tends to be discontinuous. The presence of at least 20 volume percent alumina insures continuity of the alumina phase under most ordinary conditions.
  • the amount of alumina is restricted to 80 volume percent because more alumina tends to prevent continuity of the electrically conductive phase of metalline and intermetallic.
  • alumina present in the compositions of this invention in amounts ranging from 30 to 70 volume percent and most preferably in amounts ranging from 40 to 60 volume percent, because such amounts virtually guarantee uninterrupted phases of alumina and the electrically conductive phase.
  • Alumina suitable for use in the compositions of this invention can be in many forms so long as it is finely divided. Thus, it can be in the form of gamma, eta, or alpha alumina or mixtures of these.
  • Alpha alumina is a preferred starting material because it does not have as high a specific surface areas as gamma or eta alumina and is likely to contain less adsorbed water which can be deleterious.
  • the alumina to be used should be sufliciently finely divided to produce the compositions of this invention with an average grain size of less than 10 microns.
  • a suitable starting alumina is alpha alumina with a specific surface area of more than 2 m. g. and preferably 5 to 25 m. g.
  • Such alumina can be obtained most simply by heating anhydrous alurninum diacetate to 1200 C. for 3 or more hours.
  • Alcoa Superground Alumina XA-l6 which is characterized by X-ray examination as alpha alumina, and has a specific surface area of about 13 square meters per gram which is equivalent to a spherical particle size of about 115 millimicrons.
  • Carbides or nitrides (metalline):
  • the metalline is used in the compositions of this invention in amounts ranging from to 78 volume percent and is selected from the group consisting of titanium carbide, titanium nitride, zirconium carbide, zirconium nitride, niobium carbide, niobium nitride, tantalum carbide, tantalum nitride, and mixtures thereof.
  • zirconium carbide or zirconium nitride When zirconium carbide or zirconium nitride is used, it may contain a small amount of hafnium carbide or nitride (i.e., 1% to 5% by weight, usually about 2%) which is normally present as an impurity in technical grades of zirconium compounds.
  • Preferred amounts of metalline range from 15 to 45 volume percent and most preferred amounts range from to 40 volume percent. These amounts contribute most effectively to properties such as hardness and wear resistance in the compositions of this invention.
  • the metallines can be obtained commercially or can be synthesized by methods well known to the art.
  • the metallines should preferably have a particle size of less than 5 microns and more preferably less than 2 microns. If the starting material is appreciably larger than 5 microns in particle size it can be pre-ground to reduce its size to that which is acceptable. Of course the milling of the components of this invention, which is carried out to obtain a high degree of homogeneity, will result in some comminution of the carbide and the other starting components.
  • Titanium nitride, titanium carbide, zirconium nitride, and zirconium carbide are preferred for use in the compositions of this invention as they are readily available, result in compositions which have an excellent balance of physical properties, and demonstrate great effectiveness when used to cut or mill ferrous alloys.
  • the intermetallics suitable for use in this invention are selected from the group consisting of iron aluminide, iron titanide, cobalt aluminide, cobalt titanide, nickel aluminide, nickel titanide, tungsten aluminide, molybdenum aluminide, niobium aluminide, tantalum aluminide, titanium aluminide, zirconium aluminide, and mixtures thereof.
  • the intermetallic should be present in amounts ranging from 2 to 30 volume percent. At least two volume percent is necessary in order to provide any significant bonding in the body and amounts greater than this give rise to additional strength and toughness, although decreased wear resistance. Above 30 volume percent little further improvement in strength is obtained but the wear resistance is decreased considerably.
  • zirconium aluminide or zirconium titanide when used, it may contain the usual amounts of hafnium, i.e., from 1% to 5% by weight.
  • Preferred amounts of the intermetallic are from 3 to 25 volume percent and are more preferably from 4 to 20 volume percent since it is over these ranges that the best balance between strength, toughness and wear resistance has been obtained.
  • the preferred intermetallic materials are the aluminides and the most preferred intermetallics are iron aluminide, cobalt aluminide, and nickel aluminide because they are the most ductile of the refractory intermetallic bindners used in the compositions of the invention.
  • Aluminides of nickel, molybdenum, and niobium available from Cerac, Inc.; iron aluminide from Shieldalloy Corp.; iron titanide from Shieldalloy Corp. or Fotte Mineral Co.; and nickel titanide from Metal Hydrides, Inc., may be used. Also the intermetallic compounds can be synthesized in situ by mixing together the correct ratio of elements in the powder from which the dense bodies of the invention are made.
  • the intermetallics can be synthesized by melting together the stoichiometric ratio of the components in an inert refractory crucible in a vacuum furnace. After allowing to cool, the solid billet of the intermetallic can frequently be broken up in a hammer mill and ground to a fine mesh size in a ball mill. Alternatively, a fine powder can be obtained by atomizing the molten intermetallic by the procedures known to the art for the production of atomized metal powders. Although minus 50 mesh powders (US. Standard Sieve Series) may be used to prepare compositions of the invention, minus 200 mesh powders are preferred, and minus 325 mesh most preferred.
  • the fine intermetallic powders prepared as described above can then be incorporated in compositions to be used in fabricating dense bodies of the invention.
  • Impurities The components used in the compositions of this invention should be essentially pure. It is desirable to exclude impurities such as oxygen which would tend to have deleterious effects on the dense compositions of this invention. H
  • the intermetallic can contain small amounts of metals such as titanium, zirconium, tantalum or niobium as minor impurities, although low melting metals like lead should be excluded.
  • metals such as titanium, zirconium, tantalum or niobium as minor impurities, although low melting metals like lead should be excluded.
  • oxidation particularly of the 'itenmetallic, occurs easily and should be avoided.
  • compositions of this invention can also be characterized on the basis of their structural characteristics.
  • compositions of this invention are characterized as containing two interpenetrating three-dimensional networks: one of alumina and one of intermetallic bonded carbide or nitride.
  • the presence of these co-continuous networks can be determined from analysis of the dense composition.
  • the continuity of the network of alumina can be ascertained by removing the metalline and intermetallic by anodic etching in 10% ammonium bifluoride solution. Such etching while not apparently affecting the appearance of the composition, removes the electrically conducting material from the outer portion of the compositions nearest the surface and results in a non-conducting surface having an electrical resistivity of greater than 100,000 microohm-centimeter. Proof of continuity of the alumina phase is the solid coherent surface that exists despite the obvious removal of the conducting materials.
  • a convenient method for removing all of the metalline and intermetallic from the compositions of this invention and thus demonstrating the presence of a threedimensional skeleton of alumina is to immerse small bars of the composition in a mixture of 25 cc. of 12 percent hydrofluoric acid and cc. of concentrated nitric acid.
  • a bar 0.070 inch by 0.070 inch by 1.00 inch in dimensions can be left in the acid mixture for 24 hours during which the mixture is heated on a streambath. The portion of the bar which remains after 24 hours is alumina and can be examined for continuity and strength by the usual means.
  • compositions of this invention containing 40 or more volume percent of alumina yield very strong alumina skeletons by the above method of analysis.
  • an alumina skeleton obtained from a composition of this invention which contains about 60 volume percent alumina retains a transverse rupture strength of 15,000 psi.
  • the presence of alumina in amounts of about 30 volume percent tends to produce a fairly strong skeleton with transverse rupture strengths of about 1,400 psi.
  • compositions of this invention preferably have a specific electrical resistivity of less than about 1 ohm-centimeter, more preferably less than about 25,000 micro-ohm-centimeter and most preferably less than 5,000 micro-ohm-centimeter.
  • compositions of this invention are also characterized as having two continuous interpenetrating networks with very similar thenmal coefficients of expansion.
  • coefiicient of expansion of the alumina phase as well as the metalline and intermetallic phase will range between 4 10 and 5X10 inches/inch/ F. at temperatures from room temperature up to 1000" F.
  • cutting tips of the compositions of this invention are able to undergo extreme temperature change with little or no thermal strain being generated within the composition.
  • the compositions are very resistant to thermal shock both as regards shattering and as regards surface heat cracking.
  • compositions of this invention are also characterized as having a fine average grain size, smaller than 10 'microns and preferably smaller than 5 microns in number average grain diameter.
  • the number average grain size and the size distribution are obtained from enlarged electron micrographs on polished etched surfaces using an extension of the methods of John E. Hilliard described in Metal Progress, May 1964, pages 99 to 102, and of R. L. Fullman, described in the Journal of Metals, March 1953, page 447 et seq.
  • the grain size is uniform and homogeneous throughout the composition and there is essentially no porosity in the dense compositions of this invention.
  • Distribution of the co-continuous phases is also uniform and homogeneous, and generally speaking any area 100 microns square which is examined microscopically at 1000 magnification will appear the same as any other area 100 microns square, within conventional statistical distribution limits.
  • the fine grain size of the compositions of this invention is of course at least partly responsible for the continuity of the interpenetrating (i.e., alumina skeleton and the metalline-intermetallic matrix) phases. However, it also contributes along with the homogeneity and low porosity to the abrasion resistance of the compositions of this invention. Metal inclusions such as the carbide inclusions in cast iron abrade even the hardest of the metal-bonded, carbide cutting tools. Nevertheless the compositions of this invention are outstandingly abrasion resistant.
  • compositions of this invention are important because many of the characteristics of the compositions are achieved as a result of the manner in which they are prepared. Thus, the use of fine-grained starting materials and thorough milling of the mixed components are directly related to the fine grain size and uniform homogeneity of the compositions. Other precautions observed in preparing the compositions of this invention which have important effects on the products are:
  • Milling and powder recovery Milling of the components, to homogeneously intermix them and obtain very fine grain sizes, is carried out according to the practives common in the art. Optimum milling conditions will ordinarily involve a mill half-filled with a grinding medium such as cobalt bonded tungsten carbide balls or rods, a liquid medium such as a hydrocarbon oil, an inert atmosphere, grinding periods of from a few days to several weeks, and powder recovery also in an inert atmosphere. The recovered powder is ordinarily dried at temperatures of around ISO-200 C. under vacuum, followed by screening and storage when desirable in an inert atmosphere.
  • a grinding medium such as cobalt bonded tungsten carbide balls or rods
  • a liquid medium such as a hydrocarbon oil
  • an inert atmosphere grinding periods of from a few days to several weeks
  • powder recovery also in an inert atmosphere The recovered powder is ordinarily dried at temperatures of around ISO-200 C. under vacuum, followed by screening and storage when desirable in an inert atmosphere.
  • compositions of this invention are ordinarily consolidated to dense pore-free bodies by sintering under pressure. Consolidation is oridinarily carried out by hot-pressing the mixed powdefs in a graphite mold under vacuum.
  • the powders When the powders are hot-pressed they are placed in the mold and inserted into the heated zone of the hot press without application of pressure thus allowing volatile impurities to escape before the composition is densified.
  • Full pressure is usually applied at or near the maximum temperature.
  • Maximum temperatures range between 1400 and 1900 C. depending upon the amount of intenmetallic present and will ordinarily be between 1600 and 1800 C.
  • Maximum pressures range between 500 and 4000 psi. with lower pressures being used usually in combination with lower temperatures for compositions with a high intermetallic content. Conversely, higher pressures and temperatures are employed for compositions low in intermetallic.
  • composition not be heated to a temperature, or for a period of time, which is in excess of that required to eliminate porosity and achieve density.
  • Such higher temperatures or longer times result in undesirable grain growth and a resultant coarsening of the structure, and can even result in development of secondary porosity due to recrystallization, or in the formation of undesirable phases.
  • pressing temperatures in the range of 1700 to 1900 C. are usually employed for the preferred products of this invention and maximum temperature is applied for less than 30 minutes, usually no more than minutes and preferably no more than 6 minutes after which the product is removed from the hot zone.
  • the compositions of this invention are compacted such that porosity is eliminated and maximum density attained without undue recrystallization.
  • Such products are characterized by their fine grain size and outstanding transverse rupture strength.
  • compositions of this invention can also be densified by cold-pressing and sintering under high vacuum provided that the above limitation on minium sintering time at maximum temperature is followed. It is preferred to isostatically press the powder in a sealed rubber mold suspended in water in an isostatic press capable of applying high pressures (60,000 p.s.i.) hydraulically.
  • compositions of this invention can be employed in a variety of types of cutting tools designed for numerous use applications. They can be molded or cut into standardized disposable inserts, suitable for turning, boring or milling. Or, they can be laminated with or otherwise bonded to metal-bonded carbides or tool steels for regrindable types of tooling. They are suitable generally for metal removal of ferrous metals including machining or cutting hardened steels, alloy steels, maraging steels, cast iron, cast steel, nickel, nickel-chromium alloys, nickel based and cobalt superalloys, as well as for cutting non-metallic materials such as fiber glass-plastic laniinates and ceramic compositions.
  • compositions of this invention are best suited for cutting at very high speeds such metals as alloy steels (800 surface feet per minute) and cast iron (1200 surface feet per minute). This is so because of the great resistance to cratering and edge wear and retention of good hardness of the compositions of this invention at elevated temperatures. Because of their good thermal shock resistance they are particularly well suited for making repeated short cuts or other interrupted cuts in which the temperature of the cutting edge fluctuates rapidly.
  • compositions of this invention can also be used in general refractory uses such as thread guides, bearings,
  • compositions of this invention are useful in any application where their combination of refractory properties, electrical conductivity, metallophilic nature, and thermal shock resistance offer an advantage such as in making an electrically conducting ceramic-like grit for grinding wheels to be employed in electrolytic grinding.
  • the bodies of the invention are extremely resistant to oxidation at high temperatures and this, together with their electrical conductivity, enables them to be used as furnace heating elements which can maintain high temperatures for long periods in oxidizing atmospheres.
  • EXAMPLE 1 This is an example of a composition containing 50 volume percent of aluminum oxide, 45 volume percent of titanium carbide and 5 volume percent of nickel aluminide.
  • the alumina in the form of very finely divided alpha alumina is prepared from colloidal boehmite, as described in US. 2,915,475 by heating for 20 hours in air at 350 C., then increasing the heat to 500 C. and holding at this temperature for 15 hours, and finally increasing the heat at about C. per hour to a goal temperature of 1240 C., where it is held for 3 days.
  • a sample of the cooled product is then treated with hydrofluoric acid and is 88.5% insoluble in 24% aqueous hydrofluoric acid over a period of 16 hours, indicating an alpha alumina content of about 88.5
  • the specific surface area of the hydrofluoric acid insoluble alumina is 6.3 m. g. as measured by nitrogen adsorption using the Brunauer, Emmett, Teller method.
  • This surface area corresponds to a crystallite size of alpha alumina of about 240 millimicrons average particle diameter. Under an electron microscope the alpha alumina appears as aggregates of alumina crystals in the range from 100 to 300 millimicrons in diameter.
  • the density of the free-flowing finely divided alpha alumina is 0.5 g./cc., as obtained by measuring the volume of a weighed sample after tapping in a 100 cc. glass cylinder.
  • the titanium carbide to be used has a nominal particle size of 2 microns and a specific surface area of 3 mF/g. as determined by nitrogen adsorption.
  • An electron micrograph shows that the titanium carbide grains are approximately 2 microns in diameter and are clustered in the form of loose aggregates.
  • the carbon content is 19.0%, and the oxygen analysis indicates a titanium dioxide content of about 2.5%.
  • the nickel aluminide to be used has a particle size such that it all passes through a 325 mesh screen.
  • the specific surface area of the powder is 0.3 mF/g. as determined by nitrogen adsorption. This specific area cor responds to particles of nickel aluminide of about 3.4 microns average particle diameter.
  • the oxygen content The powders are milled by loading 4000 grams of preconditioned cylindrical cobalt-bonded tungsten carbide inserts, inch long and A inch in diameter, into a 1.3 liter steel rolling mill about 6 inches in diameter, also charged with 375 ml. of Soltrol (saturated paraffinic hydrocarbon, approximate boiling point C.). The mill is then charged with 59.75 grams of the alpha alumina, 67.50 grams of the titanium carbide powder, and 8.78 grams of the nickel aluminide powder, all as above described.
  • the mill is then sealed and rotated at 90 rpm. for 5 days.
  • the mill is then opened and the contents emptied through a No. 7 sieve size screen while keeping the milling inserts inside.
  • the mill is then rinsed out with Soltrol 130 several times until all of the milled solids are removed.
  • the milled powder is transferred to a vacuum evaporator, and the excess hydrocarbon is decanted off after the suspended material has settled.
  • the wet residual cake is then dried under vacuum with the application of heat until the temperature within the evaporator is between 200 and 300 C., and the pressure is less than about 1.0 millimeter of mercury. Thereafter the powder is handled entirely in the absence of air.
  • the dry powder is passed through a 40 mesh screen in a nitrogen atmosphere, and then stored under nitrogen in sealed plastic containers,
  • a consolidated billet is prepared from this powder by hot pressing the powder in a cylindrical graphite mold having a square cavity 1 inches x 1 inches and fitted with opposing close-fitting pistons.
  • One piston is held in place in one end of the mold cavity while 25 grams of the powder is charged into the cavity under nitrogen and evenly distributed by rotatin the mold and tapping it lightly on the side.
  • the upper piston. is then put in place under hand pressure.
  • the assembled mold and contents are then placed in a vacuum chamber of a vacuum hot press, the mold is held in a vertical position, and the pistons extending above and below are engaged between opposing graphite rams of the press under pressure of about 100 to 200 psi. Within a period of a minute the mold is raised into the hot zone of the furnace at 1500 C.
  • the furnace temperature is increased while the positions of the rams are locked so as to prevent further movement during the heatup period.
  • the temperature is raised from 1500 to 1800 C. in 10 minutes, and the temperature of the mold is then held at 1800 C. for another 2 minutes to ensure uniform heating of the sample.
  • a pressure of 4000 psi. is then applied through the pistons for four minutes.
  • the mold and contents still being held between the opposing rarns, is moved out of the furnace into a cool zone where the mold and contents are cooled to dull red heat in about 5 minutes.
  • the mold and contents are then removed from the vacuum furnace and the billet is removed from the mold and sand blasted to remove any adhering carbon.
  • the billet which is a 1 inch square about 0.30 inch in thickness, is cut so that a piece slightly larger than one half inch square is removed from the center. Strips 0.070 inch in thickness are cut from the material remaining to each side of this center piece and are further out in 0.70 inch X 0.70 inch square bars for testing transverse rupture strength. Other portions of the billet are used for indentation hardness tests and for other product characterization.
  • the transverse rupture strength as measured by bending the 0.070 inch x 0.070 inch test bars on a inch span is 165,000 p.s.i.
  • the hardness is 93.2 on the Rockwell A scale.
  • the square center piece is finished as a cutting tip to exact dimensions, /2 inch x /2 inch x inch and the corners are finished with a & inch radius, a style known in the industry as SNG-432.
  • This tip is employed as a single tooth in a 4 inch diameter milling cutter to face mill dry and on center 4340 steel (R 36) bars 2 inches wide at a surface speed of 535 feet per minute and a feed rate of 0.0053 inch per tooth with a depth of cut of 0.100 inch.
  • Milling is continued under these conditions for 36 inches of bar length and upon examination the cutting tip shows only 0.005 inch of uniform flank wear, and 0.008 inch of local flank wear, with no cratering on the face of the tool and no braking or chipping of the edge, Under these same cutting conditions, commercially available ceramic cutting inserts chip and break after cutting 2 to 11 inches.
  • the tip is also employed as a cutting tool on Class 30 (170 BHN) gray cast iron in a high speed turning test at 1250 surface feet per minute, using a feed of 0.005
  • the tool is also used to dry turn extremely hard 4340 steel (54 R at 400 s.f.m., 0.005 i.p.r. and 0.050" depth and is found to have a tool life of 15 minutes. Under the same conditions, a commercial ceramic tool is found to have a tool life of 5 minutes and a commercial TiC-Mo-Ni tool fails immediately.
  • Example 2 The procedure of Example 1 is repeated except that the components are used in amounts as follows: 66.3 grams of alumina powder, 34.2 grams of titanium carbide powder, and 8.18 grams of nickel aluminide. These amounts correspond to a composition containing 70 volume percent alumina, 25 volume percent titanium carbide and 5 volume percent nickel aluminide.
  • the tip is employed as a cutting tool on Class 30 BHN) gray cast iron in a high speed turning test at 1250 surface feet per minute, using a feed of 0.005 inch per revolution and a depth of cut of 0.050 inch. After 10 minutes of operation the tip has a uniform flank wear of 0.008 inch and a local flank wear of 0.012 inch.
  • This tip is also employed as a single tooth in a 4 inch diameter milling cutter to face mill dry and on center 30 (170 BHN) gray cast iron bars 2 inches wide at a surface speed of 1575 feet per minute and a feed rate of 0.010 inch per tooth with a depth of cut of 0.250 inch.
  • Milling is continued under these conditions for 220 inches of bar length without wearing out.
  • the cutting tip shows only 0.012 inch of uniform flank wear, and 0.036- inch of local flank wear, with no cratering on the face of the tool and no breaking or chipping of the edge.
  • commercially available ceramic cutting inserts break immediately.
  • Example 3 The procedure of Example 1 is repeated except that the following components are used: 71.6 grams of alumina powder, 37.0 grams of titanium carbide powder, and 14.8 grams of molybdenum aluminide (Mo Al) powder. These amounts correspond to a composition containing 70 volume percent alumina, 25 volume percent titanium carbide and 5 volume percent molybdenum aluminide.
  • a cutting tip prepared as in Example 1 from this hot pressed composition, performs exceptionally well as a cutting tip for metal cutting by turning and milling.
  • the tip is employed as a cutting tool on Class 30 (70 BHN) gray cast iron in a high speed turning test at 1250 surface feet per minute, using a feed of 0.005 inch per revolution and a depth of cut of 0.050 inch. After 10 minutes of operation the tip has a uniform flank wear of only 0.002 inch.
  • the same tip is also employed as a single tooth in a 4 inch diameter milling cutter to face mill dry and on center 4340 steel (R 36) bars 2 inches wide at a surface speed of 535 feet per minute and a feed rate of 0.0053 inch per tooth with a depth of cut of 0.100 inch.
  • Milling is continued under these conditions for 36 inches of bar length without wearing out.
  • the cutting tip shows only 0.003 inch of uniform flank wear and 0.006 inch of local flank wear, with no cratering on the face of the tool and no breaking or chipping of the edge.
  • commercially available ceramic cutting tools fail by chipping after cutting between 2 and 11 inches.
  • EXAMPLES 47 The following examples are carried out using the raw materials and procedures described in Example 1, except TAB LE I Preparation and fabrication Hot press cycle Powder composition Mill- Insertime Metal cutting test mg tion Max. at max. Example Metalline Interconditemp, temp, temp., T.R. Perform- N o. AlzOa phase metallic tions 0. min. Kp.s.i. Type of test ance 4 W0 1 30 45 T10 25 NiAl B 1, 500 1, 600 4 140 High speed turning grey cast iron Very good.
  • AluminaAlcoa Superground Alumina XA-16 characterized by X-ray examination as alpha alumina and has a specific surface area of 13 square meters per gram.
  • Zirconium carbide-Materials for *Industry fine powder characterized by X-ray examination as pure zirconium carbide and has a particle size less than one micron as measured with a Fisher Sub-Sieve Sizer. Specific surface area of the powder is 0.5 m. g. and oxygen content only 0.18%.
  • Titanium nitride Materials for Industry minus 325 mesh titanium nitride powder, characterized by X- ray as pure titanium nitride.
  • the specific surface area of the powder is 1.1 m. /g., oxygen content is 0.87%, and total carbon content 0.33%. Chemical analysis shows that the titanium content of the powder is 76.19%.
  • Tantalum aluminide-Fine powder minus 325 mesh, characterized by X-ray examination as pure TaAl
  • Iron aluminideFine powder, minus 325 mesh characterized by X-ray examination as pure FeAl.
  • Nickel titanide-Fine powder minus 325 mesh characterized by X-ray examination as pure Ni Ti.
  • the milling conditions designated A, B and C in Table 1 correspond to the general conditions of Example 1 with the following provisions:
  • the metal cutting tests in Table I correspond to the general conditions of the cutting tests in Example 1 with the following additional: High Speed Turning Test on AISI 1045 carbon steel (Brinell Hardness Number of 183); the speed is 900 surface feet per minute (s.f.m.); the feed is 0.005 inch per revolution (i.p.f.); the depth of cut is 0.050 inch; and there is negative rake. Uniform and local flank wear is measured after 10 minutes of dry turning.
  • a dense refractory composition consisting essentially of:
  • a metalline selected from the group consisting of titanium carbide, titanium nitride, zirconium carbide, zirconium nitride, niobium carbide, niobium nitride, tantalum carbide, tantalum nitride, and mixtures thereof;
  • an intermetallic selected from the group consisting of iron aluminide, iron titanide, cobalt aluminide, cobalt titanide, nickel aluminide, nickel titanide, tungsten aluminide, molybdenum aluminide, niobium aluminide, tantalum aluminide, titanium aluminide, zirconium aluminide, and mixtures thereof;
  • composition having the further limitations that:
  • (A) the average grain size is smaller than 10 microns
  • composition is composed of two interpene trating three-dimensional networks, one network consisting essentially of alumina and the other network consisting essentially of the metalline and the intermetallic;
  • the volume percent of the metalline must not be less than the volume percent of the intermetallic.
  • volume percent of alumina ranges from 40 to 60.
  • the refractory composition of claim 1 wherein the metalline is selected from the group consisting of titanium nitride, titanium carbide, zirconium nitride, and zirconium carbide.
  • intermetallic is selected from the group consisting of iron aluminide, cobalt aluminide, and nickel aluminide.
  • the dense refractory composition consisting essentially of:
  • composition having the further limitations that:
  • (A) the average grain size is less than 5 microns
  • composition is composed of two interpenetrating three-dimensional networks, one network consisting essentially of alumina and the other network consisting essentially of the metalline and the intermetallic.

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Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2314384A1 (de) * 1972-03-23 1973-10-18 Norton Co Dichte siliciumcarbidkoerper und verfahren zu deren herstellung
WO1981001143A1 (fr) * 1979-10-26 1981-04-30 Minnesota Mining & Mfg Compositions de ceramique
WO1981001144A1 (fr) * 1979-10-26 1981-04-30 Minnesota Mining & Mfg Materiaux ceramiques resistants a l'usure
US4356272A (en) * 1980-03-29 1982-10-26 Nippon Tungsten Co., Ltd. Sintered bodies Al2 O3 -TiC-TiO2 continuing yttrium (y)
USRE32093E (en) * 1971-05-26 1986-03-18 General Electric Company Aluminum oxide coated titanium-containing cemented carbide product
EP0174463A1 (fr) * 1984-07-13 1986-03-19 NGK Spark Plug Co. Ltd. Procédé pour la fabrication de matériaux céramiques résistant à la chaleur et à l'usure, produit de ce procédé et produit de départ pour ce procédé
USRE32110E (en) * 1971-05-26 1986-04-15 General Electric Co. Aluminum oxide coated cemented carbide product
US4788167A (en) * 1986-11-20 1988-11-29 Minnesota Mining And Manufacturing Company Aluminum nitride/aluminum oxynitride/group IVB metal nitride abrasive particles derived from a sol-gel process
US4855264A (en) * 1986-11-20 1989-08-08 Minnesota Mining And Manufacturing Company Aluminum oxide/aluminum oxynitride/group IVB metal nitride abrasive particles derived from a sol-gel process
US4957886A (en) * 1986-11-20 1990-09-18 Minnesota Mining And Manufacturing Company Aluminum oxide/aluminum oxynitride/group IVB metal nitride abrasive particles derived from a sol-gel process
US5196385A (en) * 1985-08-06 1993-03-23 Ngk Spark Plug Co., Ltd. Process for the preparation of a heat-resistant and wear resistant ceramic material
US8708033B2 (en) 2012-08-29 2014-04-29 General Electric Company Calcium titanate containing mold compositions and methods for casting titanium and titanium aluminide alloys
US8858697B2 (en) 2011-10-28 2014-10-14 General Electric Company Mold compositions
US8906292B2 (en) 2012-07-27 2014-12-09 General Electric Company Crucible and facecoat compositions
US8932518B2 (en) 2012-02-29 2015-01-13 General Electric Company Mold and facecoat compositions
US8992824B2 (en) 2012-12-04 2015-03-31 General Electric Company Crucible and extrinsic facecoat compositions
US9011205B2 (en) 2012-02-15 2015-04-21 General Electric Company Titanium aluminide article with improved surface finish
US9192983B2 (en) 2013-11-26 2015-11-24 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9511417B2 (en) 2013-11-26 2016-12-06 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9592548B2 (en) 2013-01-29 2017-03-14 General Electric Company Calcium hexaluminate-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US10391547B2 (en) 2014-06-04 2019-08-27 General Electric Company Casting mold of grading with silicon carbide

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BR7604418A (pt) * 1975-07-09 1978-01-31 Teledyne Ind Composicao de material e processo para sua formacao
AU512633B2 (en) * 1976-12-21 1980-10-23 Sumitomo Electric Industries, Ltd. Sintered tool
GB2110246B (en) * 1981-02-23 1985-02-06 Vni Instrument Inst Multilayer coating for metal-cutting tool
DE3365733D1 (en) * 1982-12-30 1986-10-02 Alcan Int Ltd Metallic materials reinforced by a continuous network of a ceramic phase

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE32093E (en) * 1971-05-26 1986-03-18 General Electric Company Aluminum oxide coated titanium-containing cemented carbide product
USRE32110E (en) * 1971-05-26 1986-04-15 General Electric Co. Aluminum oxide coated cemented carbide product
DE2314384A1 (de) * 1972-03-23 1973-10-18 Norton Co Dichte siliciumcarbidkoerper und verfahren zu deren herstellung
WO1981001144A1 (fr) * 1979-10-26 1981-04-30 Minnesota Mining & Mfg Materiaux ceramiques resistants a l'usure
WO1981001143A1 (fr) * 1979-10-26 1981-04-30 Minnesota Mining & Mfg Compositions de ceramique
US4356272A (en) * 1980-03-29 1982-10-26 Nippon Tungsten Co., Ltd. Sintered bodies Al2 O3 -TiC-TiO2 continuing yttrium (y)
EP0174463A1 (fr) * 1984-07-13 1986-03-19 NGK Spark Plug Co. Ltd. Procédé pour la fabrication de matériaux céramiques résistant à la chaleur et à l'usure, produit de ce procédé et produit de départ pour ce procédé
US4839315A (en) * 1984-07-13 1989-06-13 Ngk Spark Plug Co., Ltd. Process for the production of ceramic materials having heat and wear resistance
US5196385A (en) * 1985-08-06 1993-03-23 Ngk Spark Plug Co., Ltd. Process for the preparation of a heat-resistant and wear resistant ceramic material
US4855264A (en) * 1986-11-20 1989-08-08 Minnesota Mining And Manufacturing Company Aluminum oxide/aluminum oxynitride/group IVB metal nitride abrasive particles derived from a sol-gel process
US4957886A (en) * 1986-11-20 1990-09-18 Minnesota Mining And Manufacturing Company Aluminum oxide/aluminum oxynitride/group IVB metal nitride abrasive particles derived from a sol-gel process
US4788167A (en) * 1986-11-20 1988-11-29 Minnesota Mining And Manufacturing Company Aluminum nitride/aluminum oxynitride/group IVB metal nitride abrasive particles derived from a sol-gel process
US8858697B2 (en) 2011-10-28 2014-10-14 General Electric Company Mold compositions
US9011205B2 (en) 2012-02-15 2015-04-21 General Electric Company Titanium aluminide article with improved surface finish
US8932518B2 (en) 2012-02-29 2015-01-13 General Electric Company Mold and facecoat compositions
US9802243B2 (en) 2012-02-29 2017-10-31 General Electric Company Methods for casting titanium and titanium aluminide alloys
US8906292B2 (en) 2012-07-27 2014-12-09 General Electric Company Crucible and facecoat compositions
US8708033B2 (en) 2012-08-29 2014-04-29 General Electric Company Calcium titanate containing mold compositions and methods for casting titanium and titanium aluminide alloys
US8992824B2 (en) 2012-12-04 2015-03-31 General Electric Company Crucible and extrinsic facecoat compositions
US9803923B2 (en) 2012-12-04 2017-10-31 General Electric Company Crucible and extrinsic facecoat compositions and methods for melting titanium and titanium aluminide alloys
US9592548B2 (en) 2013-01-29 2017-03-14 General Electric Company Calcium hexaluminate-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9192983B2 (en) 2013-11-26 2015-11-24 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US9511417B2 (en) 2013-11-26 2016-12-06 General Electric Company Silicon carbide-containing mold and facecoat compositions and methods for casting titanium and titanium aluminide alloys
US10391547B2 (en) 2014-06-04 2019-08-27 General Electric Company Casting mold of grading with silicon carbide

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NL7002932A (fr) 1970-09-07
DE2009696A1 (de) 1970-09-17
FR2037480A5 (fr) 1970-12-31

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