DK153536B - COMPOSITION MATERIALS INCLUDING A POLYCRYSTALLIC DIAMOND BODY AND A SILICON CARBID OR SILICON NITRATE SUBSTANCE, AND A PROCEDURE FOR MANUFACTURING THE MATERIAL - Google Patents

Description

DK 153536 B

The invention relates to a composite material comprising a poly-crystalline diamond body and a silicon carbide or silicon nitride substrate.

U.S. Patent No. 4,042,347 discloses polycrystalline 5 diamond bodies in which a metal and polyurethane matrix is used as a binder, but a technical impediment to a high density diamond composite mat (large volume content of diamond) and manufactured below the diamond stability printing range has so far been lacking. developing a suitable binder which was capable of penetrating or infiltrating the capillary cavities in a tightly packed diamond powder of fine particle drying. The binder must also form a thermal stable, strong bond with the diamond and must not transform the diamond ten! graphite or react too far with the diamond.

This barrier has now been overcome by the composite material 15 of the present invention, which comprises a polycrystalline diamond nitride substrate and a silicon carbide or silicon nitride substrate, and is characterized in that the polycrystalline silicon substrate is bonded to a single polycrystalline silicon substrate or piece, wherein the 20 polycrystalline diamond body consists of a mass of diamond cross staii which are firmly bound ten! each other with a silicon atomic binder comprising silicon carbide and a carbide and / or silicon of a metal component forming a silicon with silicon, the diamond crystals having a size of from 1 to 1000 pmf of the diamond requirement of 70% to 90% of the body volume, the silicon atomic binder constitutes up to 30% of the body volume and is at least substantially uniformly distributed within the body, the portion of the binder which contacts the surface of the diamond crystals consists at least for the greater part. of the silicon carbide, the diamond gel is at least substantially free of pore, the substrate varies in density from 85% to 100% of the theoretical density of silicon carbide or from 80% to 100% of the theoretical density of silicon nitride and contains silicon carbide in Si Amount of at least 90% of the weight of the substrate, the polycrystalline diamond body forms an interface with the silicon carbide or silicon nitride substrate, and the binder extends from the crystalline diamond body to the contact surface of the substrate and fills at least substantially the pores of the interface, so that the interface is at least substantially pore-free.

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In the composite material of the present invention, an eutectiferous, silicon-rich alloy which penetrates well into the capillary cavities of a compacted diamond crystal mass and wets the crystals to form a strong, bonded diamond body is used. In addition, the penetrating alloy forms a strong bond with a silicon carbide or silicon nitride substrate. Furthermore, the silicon-rich alloy can be introduced into a compressed diamond crystal mass under pressure substantially lower than those required in the diamond stability range to provide a "polycrystalline diamond body / silicon carbide or various silicon nitride substrate" composites. configurations and sizes within a wide size range.

The composite material is useful as abrasive material, cutting tool, nozzle or other abrasion resistant component.

The invention also relates to a method ten. manufacture of the composite material according to the invention, characterized in that: a) a eutectic-containing, silicon-rich solid alloy has 20 solid components which produce a eutectic-containing silicon-rich alloy, a diamond crystal mass and a silicon carbide or silicon nitride substrate or silicon nitride substrate or the diamond crystal mass being placed between and in contact with the substrate and the eutectic-containing, silicon-rich solid alloy, at least one of the components producing a eutectic-containing, silicon-rich alloy, and the eutectic-containing, silicon-rich alloy, consist of silicon and a metal, with silicon d. (B) placing the container and its contents in a pressure transmitting powder medium which transmits applied pressure substantially undiminished and remains substantially unsintered during heat pressing; (c) applying a sufficiently substantially isostatic pressure to the container; and its contents via the powder medium to substantially completely uniformly stabilize the dimensions of the container and the content to provide a front stub, essentially an isostatic system comprising the powder enclosed container, whereby the 3

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provided; the density of compressed diamond crystal mass constitutes more than 70% by volume of the volume of the compressed diamond crystal clay; (d) hot-pressed substantially isostatic system 5 to produce a liquid, eutectic-containing, silicon-rich alloy that penetrates into the void. the compressed diamond crystal mass and comes into contact with the contact surface of the substrate which forms an interface to the compressed diamond crystal mass, the hot pressing being carried out at a hot pressing temperature below 1600 ° C at a hot pressing pressure sufficient to bring the liquid silicon-rich alloy to penetrate the voids in the compressed diamond crystal mass and the eutectic-containing silicon-rich solid alloy destroys the ten! producing a eutectic-high silicon-rich alloy used solid components are used in an amount sufficient to provide sufficient liquid, eutectic-high-silicon alloy to fill the voids at the hot-pressing temperature at the contact surface of the substrate and the diamond crystal mass is filled in, so that this at least substantially becomes pore-free. and wherein less than 5% by volume of the 25 diamond crystals during the hot pressing are converted to free, non-diamond carbon, and this non-diamond carbon or diamond surface of the diamond reacts with the liquid silicon-rich alloy to form the carbide; substantially isostatic system is cooled and, below, maintained under sufficient pressure to at least substantially maintain the dimensions of the hot pressed system, and f) the composite material produced in which the polycrystalline body is bonded to a silicon carbide body 35 silicon nitride substrate and the diamond crystals present in an amount constituting at least 70% by volume of the polycrystalline body are exposed.

The hot pressing in step d) should be carried out in an atmosphere which has no significant detrimental effect on the diamond crystals or

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4 on the penetrating, liquid, silicon-rich alloy or on the silicon carbide or silicon nitride substrate.

In one embodiment of the method according to the invention, in step a), as a protective container or cup, a recess is pressed which is pressed into the powder medium which transmits applied pressure substantially undiminished and which remains substantially uninterrupted during the hot pressing; and in step b), the recess and its contents are covered with an additional amount of pressure transmitting powder medium, whereby the recess is enclosed by the pressure transmitting powder medium and then steps d) to f) are performed.

In this embodiment, the recess in the pressure transmitting powder can be formed by various methods. Eg. For example, the pressure transmitting powder medium can be placed in a die, a solid form of desired size can be inserted into the powder, and the resulting system is pressed at ambient temperature under a pressure sufficient to render the powder stable in shape, i.e. give the pressed powder sufficient strength so that the mold can be removed therefrom leaving the recess it has extruded therein to act as a container for the silicon carbide or silicon nitride substrate, diamond mass and silicon rich alloy. After the silicon carbide or silicon nitride substrate, diamond mass and silicon rich alloy are placed in the recess with the diamond mass between the substrate and the alloy, an additional amount of pressure transmitting powder medium is applied to cover the recess and the whole system is cold pressed at ambient temperature to dim the ambient temperature. and its contents to provide a practically isostatic system comprising the powder-enclosed recess and the contents.

The invention will be further explained in the following with reference to some embodiments and with reference to the drawing, in which:

FIG. 1 shows a de! of a phase diagram of a silicon luminaire alloy showing the equilibrium diagram of eutectic-containing, silicon-rich zirconium alloys useful in the present invention: FIG. 2 shows a cross section of a cell, i.e. container and contents for producing penetration of silicon rich alloy according to the invention j 5

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FIG. 3 schematically shows an apparatus for applying light pressure to the cell of FIG. 2 while vibrating the cell to increase the density of the diamond crystal mass; Fig. 4 shows a cross section of an apparatus for applying at least 5 substantially isostatic pressure to the cell by means of a pressure transmitting powder medium for dimensional stabilization of the cell to provide a substantially isostatic system; FIG. 5 shows a cross section of a graphite form for simultaneously applying heat and pressure, i.e. hot pressing, to the substantially equal isostatic system, which cross section shows the cell contained therein; FIG. 6 is a vertical sectional view of a "polycrystalline diamond body / silicon carbide or silicon nitride substrate composite material made in accordance with the present invention; and FIG. 7 shows a photomicrograph (enlarged 690X) of a polished cross-sectional surface in a composite mat according to the present invention.

20

In the method according to the invention, a roof structure is formed in which the diamond crystal mass is placed between a silicon carbide or silicon nitride substrate and a eutectic-containing, silicon-rich solid alloy and is in contact with the substrate and the alloy.

In carrying out the method, the roof structure is subjected to cold pressing at ambient or room temperature to a substantially uniform stabilization of the layers of the structure. The layer structure is then subjected to hot pressing, which produces a liquid, silicon-rich alloy, which is caused by the silicon alloy to penetrate between the packed diamond crystals to contact the silicon carbide substrate.

Alternatively, the diamond crystal mass may be in contact with at least one of the components used to form the eutectic-containing silicon-rich alloy in situ, i.e. silicon or alloy metal, and the silicon carbide or silicon nitride substrate, diamond crystal mass and silicon-rich alloy forming components are subjected to an ambient temperature cold pressing step or room temperature to virtually complete stabilization of their dimensions, and then a hot pressing step

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6 liquid, eutectic-containing, silicon-rich alloy, which is caused to seep through the entire mass of compressed diamond crystals and make contact with the silicon carbide or silicon nitride substrate. The components for providing the silicon alloy are placed silently so that the formation of the silicon alloy begins before the hot pressing, i.e. Before the hot pressing temperature is reached.

The diamond crystal mass, the mass of solid, silicon-rich starting alloy, or solid components to provide the silicon-rich alloy and the silicon carbide or silicon nitride substrate can take many different forms. Eg. each mass may take the form of a diamond crystal layer between the other layers. Alternatively, the silicon-rich starting alloy may be in the form of a through-core tube or cylinder, the alloy tube being molded to form a tight fit with the inner wall of the container, and the substrate may be in the form of a rod capable of be located centers It in the core of the alloy tube, and the enclosing space between the silicon alloy tube and the substrate rod may be packed with diamond crystals.

The diamond crystals used in the present method may be natural or synthetic, i.e. manmade. They vary in size with respect to the largest dimension from ca. 1 pm to approx. 1000 µm, and the particular size or sizes used depend essentially on the specific packing or diamond crystal density desired, and also on the particular use of the body produced. Ten! most abrasive applications are preferred e.g. diamond crystals no larger than about 60 pm. In order to maximize the packing of the diamond crystals by the present method, the diamond crystals must preferably be sorted by size, so as to contain a variety of sizes, i.e. crystals of lily, medium and large size. Preferably, the size-sorted crystals should be from about. 1 µm to about 60 µm, and in this size range, preferably from 60 to 80% by volume of the total crystal mass should belong to the larger proportion of the region, 5 to 35% to 10% by volume is of medium size travel, and the remainder is of slurry crystals or particles.

The classification of the diamond crystals is facilitated by the treatment of larger diamond crystals in the jet mill. The diamond crystals are preferably chemically purified so that any oxides or other impurities 7

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are removed from their surface Prior to use in the present method. This can be done by heating the diamond crystals in hydrogen at about 900 ° C for about 1 hour.

The solid, eutectic-containing, silicon-rich starting alloy used in the process of the invention, wherein the term '' alloy 11 in this text also includes an intermetallic compound, consists of silicon and metal, i.e. an alloy metal which forms a silicide with the silicon. The present eutectic-containing silicon-rich alloy preferably comprises silicon and one of the metals cobalt 10 (Co), chromium (Cr), iron (Fe), hafnium (Hf), manganese (Mn), molybdenum (Mg), niobium (Nb) , nickel (Ni), palladium (Pd), piatin (Pt), rhenium (Re), rhodium (Rh), ruthenium (Ru), tantalum (Ta), thorium (Th), titanium (Ti), uranium (U) , vanadium (V), tungsten (W), yttrium (Y), zirconium (2r) and mixtures thereof.

The present eutectic-containing, silicon-rich starting alloy is solid at room temperature and contains more than 50 atomic percent but less than 100 atomic percent silicon. Usually, it contains a maximum of about 99.5 atomic percent silicon, the silicon content being largely dependent on the specific effect of the alloying metal on the resulting silicon-rich alloy. The present solid, silicon-rich starting alloy is eutectic-containing, i.e. it contains some eutectic structure and may be of hypo-eutectic, hypereutectic or eutectic composition.

In FIG. 1 shows, for example, that the eutectic composition 25 2 is an alloy of a particular composition which, under equal weight conditions, solidifies at cooling at constant temperature to form a solid with at least two phases and which upon heating completely melts at the same constant temperature, where this constant temperature, called the eutectic temperature, is also denoted by 2. The eutectic composition 2 is the composition at which two downward liquid lines 3 and 4 meet at the eutectic point 2 and the eutectic composition thus has a lower melting point than the adjacent hypoeutectic or hypereutectic compositions. The liquidation line is er.

In a phase diagram, the curve or line represents the temperatures under equilibrium conditions at which melting is completed during heating of the silicon alloy or solidification begins upon cooling thereof. The solid, eutectic-containing, sulfate-containing solids used in the process of the invention

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8 starting alloy is one of a series of alloys on a horizontal eutectic line 1, ie. the horizontal line passing through the eutectic point 2, extending from alloys whose composition lies to the left of the eutectic 2 in an equilibrium diagram, 5 and which contains some eutectic structure, i. a hypoeutectic alloy, for alloys, the composition of which is to the right of the eutectic 2-in-balance diagram and which contains some eutectic structure, i. a hypereutectic alloy.

The solid silicon-rich starting alloy may, but does not need it, be of the same composition as the penetrating silicon-rich alloy. If a solid, silicon-rich starting alloy becomes liquid at the hot-pressing temperature, it will have the same composition as the penetrating silicon-rich alloy. However, if only part of the silicon-rich starting alloy, viz. a hypoeutectic or hypereutectic fluid becomes liquid at the hot pressing temperature, the starting alloy does not have the same composition as the liquid, penetrating, silicon-rich alloy, and in this case the penetrating, silicon-rich alloy will contain more silicon than the hypoeutectic; eutectic starting alloy, but containing less silicon than the wasp eutectic silicon containing alloy.

In FIG. 1 further states that the composition of the penetrating eutectic-containing, silicon-rich alloy and its melting temperature used in the present invention is found on the liquid lines 3 and 4 and comprises the eutectic point 2. The region 5, delimited by 1, 25 2 and 4, comprises a solid phase ( 51) and a liquid phase, i.e. an airborne, penetration-sealing phase where the amount of solid phase increases and the amount of liquid phase decreases correspondingly as the distance to the right from eutectic point 2 along the horizontal line 1 increases, i. when the amount of silicon in the alloy is increased from the amount contained in the eutectic. Similarly, the region 6 bounded at 1, 2 and 3 comprises a solid phase ZrSi 2 and a liquid phase, i.e. a liquid penetration sealing phase where the amount of solid phase increases and the amount of liquid phase decreases correspondingly as the distance to the left of the eutectic point 2 along the horizontal line 1 increases, i.e. when the amount of silicon in the alloy is reduced from the amount of dm- contained in the eutectic.

In practicing the present process, the desired composition of the present eutectic-containing, silicon-rich penetration alloy and its melting point are found as a point 9.

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on the liquidus lines, including the eutectic point, in the phase diagram of the present silicon-rich alloy, and the hot-pressing temperature is the temperature at which such a desired silicon-rich penetration alloy composition is liquid, i.

5 sufficiently capable of flowing and penetrating through the compacted diamond mass. When a solid silicon-rich starting alloy having the same composition as the desired penetration alloy is used, the hot-pressing temperature is the temperature at which the alloy is liquid, which temperature is 10 m Preferably a maximum of about 10 ° C. 100 ° C above the melting point of the alloy, but if desired, hot pressing temperatures above this preferred maximum are useful depending on the particular alloy used. However, hot pressing temperatures above 1600 ° C are not applicable, since such temperatures tend to to transform the diamonds into graphite to a great extent.

However, if the starting alloy does not have the same composition as the desired penetration alloy, it does provide a side penetration alloy as liquid phase when heated to the melting point of the desired penetration alloy, then the hot pressing temperature is a temperature at which such penetration alloy phase is formed, i.e. about 10 ° C above the melting point of the penetration alloy phase.

Figure 1 also shows that for a particular penetration alloy 25 of hypereutectic composition, the melting point is pi iikvidus line 4. If e.g. the desired penetrating, hypereutectic icing contains 95 atomic percent Si, its melting point on the ITQ 4 is found to be approx. 1400 ° C, as shown on line 7. When the silicon-rich starting alloy has the same composition as the desired penetration alloy as shown on line 7, all starting alloy will melt at the melting temperature of 1400 ° C and the liquid or hot pressing temperature will be between 1410 ° C and preferably 1510 ° C, or up to a maximum of 1600 ° C if desired. When there. however, a silicon-rich starting alloy is a hypereutectic alloy 35 to the right of line 7 on the horizontal line 1 of the equilibrium diagram of FIG. 1, the hot pressing temperature is the temperature at which the desired penetration alloy containing 95 atomic percent Si and 5 atomic percent Zr is provided in liquid form, which will be

Q

about 1410 C.

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10

At the hot-pressing temperature, the starting alloy should provide the desired liquid alloy penetration in an amount sufficient to ten. filling the voids in the present compacted diamond mass having a crystalline density of over 70% by volume, and contacting the contact surfaces of the silicon carbide substrate while filling the pores or voids in the interface between the contact forming poly crystals! in the body and substrate so that the resulting composite has an interface which is pore-free or at least substantially pore-free.

In practice, the liquid penetration alloy at the hot-pressing temperature should be provided in an amount of at least approx. 1% by volume of the silicon-containing starting alloy.

The hot pressing is carried out at a temperature at which the penetrating silicon alloy is subjected to a pressure which only needs to be sufficient to break down resistant interfacial layers in the diamond mass which prevents penetration with the liquid mass at the hot pressing temperature. through the cavities therein, and usually this requires a minimum pressure of about 34.5 bar overpressure. Especially 20, the hot pressing pressure can be between approx. 34.5 bar overpressure and 1.4 kilobar overpressure, but usually it is between approx. SS carried overpressure and S90 carried overpressure. Hot pressing pressure in the method of the present invention over 1.4 kbbar overpressure provides no significant advantage.

By a temperature at which the penetrating alloy is liquid, in this text is meant a temperature at which the penetrating alloy is able to disperse easily. In particular, the penetrating alloy at its melting point given on the Hkvlduslin or at the eutectic point in the case of a eutectic alloy is a liquid, thick, viscous substance, but as its temperature increases from the melting point, the penetrating alloy becomes less viscous, and at at a temperature of about 10 ° C above its melting point, the liquid penetrating alloy is readily capable of being maintained. to flow, i.e. liquid. The temperature at which the penetrating silicon-rich alloy is liquid is the temperature at which it will penetrate or seep through the capillary-sized passages, voids, or voids in the present compacted diamond crystal mass having a crystalline density of over 70% by volume.

At still further temperature rise, the flowability of the 11

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liquid, penetrating, silicon-rich alloy, resulting in an increased penetration rate through the hot diamond crystal mass, and at a temperature about 10G ° C above its melting point, the penetrating alloy usually has its greatest flowability, and temperatures above this maximum are generally not necessary to apply.

The present silicon-rich alloy of eutectic composition melts at a temperature below about 1430 ° C. For the preferred group of silicon-containing alloys according to the invention, the eutectic melting point is between 870 ° C for a eutectic SiPd alloy, namely at about 56% Si, and 1410 ° C for a eutectic SiMo alloy composition, namely at about 97 atomic percent. Si. As shown in FIG. 1, the eutectic SiZr alloy contains 2 90.4 atomic percent Si and has a eutectic melting temperature of 1360 ° C.

The main phase of the present solid, silicon-rich eutectic alloy is almost pure silicon.

The present penetrating eutectic-rich silicon-rich alloy has a melting point of less than 1500 ° C, usually between 0 and 850 C and 1450 C, and the temperature at which it becomes apparent is at least about 10 ° C above the melting point.

The solid, silicon-rich starting alloy or the ten! providing the present silicon-rich alloy solid components may be in the form of a continuous solid body or in the form of a powder.

The particular amount or volume of solid silicon-rich starting alloy used may vary depending on the amount of liquid, silicon-rich + intrusion alloy it provides and the capacity of the material. Generally, the amount of the penetrating silicon alloy is from 25% to 80% by volume, but for best results 30 it is preferably between 30 and 60% by volume of the present compacted diamond crystal mass having a crystal density of over 70% by volume.

The hot pressing step used is carried out in an atmosphere which has no significant detrimental effect on the dismantling crystals or the penetrating silicon-rich alloy or the silicon carbide substrate. In particular, the hot pressing step may be carried out in practically a vacuum or in an inert gas, e.g. argon or helium, or it can be carried out in nitrogen or hydrogen. The present hot pressing is carried out sufficiently quickly so that none can be found

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12 significant reaction occurs between the penetrating, silicon-rich alloy and the nitrogen or hydrogen. The hot pressing step cannot be carried out in atmospheric air since diamond in atmospheric air at more than 800 ° C is rapidly converted to graphite and the liquid, penetrating, silicon-rich alloy would be oxidized to form solid silicic anhydride before any substantial infusion of liquid alloy into the diamond mass has taken place.

The silicon carbide substrate is a polycrystalline body having a density of between 85% and 100% of the theoretical density of silicon carbide. The silicon carbide density given herein is the relative density based on the theoretical density of silicon carbide, which is 3.21 3 g / cm. A polycrystalline silicon carbide body with a density less than 85% is not applicable as it does not have it for most applications, such as use as a tool insert required 15 mechanical strengths. Generally, the greater the density of the silicon carbide egg, the greater its mechanical strength.

The silicon nitride substrate is a polycrystalline body having a density of between 80% and 100% of the theoretical density of silicon nitride.

The silicon density indicated herein is the relative density 20 based on the theoretical density of silicon nitride, which is 3.18 g / cm. A polycrystalline silicon nitride body having a density below 80% is not usable as it will not have it for most applications, e.g. for use as tool insert, mechanical strength required. Generally, the greater the density of the silicon nitride body, the greater its mechanical strength.

For the purposes of the present invention, the polycrystalline silicon carbide or silicon nitride substrate is a hot pressed or sintered element containing silicon nitride, i.e., it contains silicon nitride in an amount of at least 90% by weight and usually at least 95% by weight and usually millimeters. 96% by weight and 99% by weight or more by weight of the substrate body. Other constituents or components other than silicon nitride in the present polycrystalline silicon nitride body should have no significant deteriorating effect on the mechanical properties of the resulting composite material. In particular, they should have no significant deteriorating effect on the properties of the silicon nitride and all the other materials used in the present process for the manufacture of the composite material or the properties of the composite material itself.

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The present silicon carbide body can be prepared by sintering processes known from U.S.A. Patent No. 4,004,934.

Briefly, the sintered silicon carbide body can be prepared by providing a submicron particle mixture of B-silicon ~ 5 carbide, boron additive, and a carbonaceous additive in the form of free carbon or a carbonaceous organic material which is heat decomposable to form free carbon and form the mixture into a green vegetable. In an alternative method, A-SiC of submicron size but with an average particle size equal to two-ten times the particle size of B-SiC is mixed with the particle mixture in an amount of 0.05% by weight and 5% by weight based on A-SiC. one. The "green" element is sintered at a temperature of between 1900 ° C and 2300 ° C to the required density.

The boron additive may be present as pure boron carbide or as a boron compound which decomposes at a temperature below the sintering temperature to form boron or boron carbide and gaseous decomposition products, and is used in an amount equal to 0.3 to 3.0% by weight of pure boron calculated from the amount of silicon wrist. During sintering, the boron additive goes into solid solution with the syncium carbide, and when amounts of the additive exceeding what corresponds to ten in about 1% by weight of pure boron are additionally a boron carbide phase is excreted.

The carbonaceous additive is used in an amount corresponding to often from ca. 0.1 to approx. 1.0 percent by weight of carbon calculated from the amount of silicon carbide. The additive may be free carbon or a solid or liquid carbonaceous organic material which completely decomposes at a temperature of 50 ° C - 1000 ° C to submicron free carbon and gaseous decomposition products. Examples of carbonaceous additives are polymers of aromatic hydrocarbons such as e.g. polyphenylene or polymethylphenylene, which is soluble in aromatic hydrocarbons.

The sintered elements comprise silicon carbide and calculated from the amount of silicon carbide from 0.3 to 3.0 weight percent boron and up to 1 weight percent free carbon. The drill is in solid solution with the silicon carbide or alternatively as the solid carbide phase in solid solution with the silicon carbide. The free carbon is present if it can be detected as submicron particles dispersed throughout the sintered solid.

Preferably, the hot pressed silicon carbide bodies can be prepared

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14 by methods described in the specification ten! U.S. Patent No. 3,853,566 and U.S. Patent No. 4,108,929.

A dispersion of silicon carbide sub-micron powder and a boron or boron carbide amount corresponding to ten! 0.5-3.0% by weight of boron is hot pressed 5 by a hot pressing process at 1900-2000 ° C and 345-690 bar overpressure to provide a boron-containing silicon carbide body. In another hot pressing process, 0.5 - 3.0% by weight of free carbon or carbonaceous additive, which can be heat-decomposed to free carbon, is included in the dispersion.

The polycrystalline silicon nitride body can be prepared by the sintering processes described in the specification described above. U.S. Patent Nos. 4,119,689 and 4,119,690.

In the specification of U.S. Patent No. 4,119,689, a sintered silicon nitride body is prepared which is produced by providing a homogeneous dispersion of suction micron drying and comprising silicon nitride and a beryllium additive which may be beryllium, beryllium carbide, beryllium fluoride, beryllium silicon nitride and mixtures thereof in an amount in which the beryllium component corresponds to from 0.1 wt% to 2 wt% pure beryllium on the basis of the amount of silicon nitride, forming the dispersion to a "green body" and sintering the "green body" by from 1S00 ° C ti! 2200 ° C in a nitrogen sintering atmosphere at a superatmospheric pressure which at the sintering temperature prevents substantial thermal decomposition of the silicon nitride and provides a sintered body having a seal of at least 25 80% of the theoretical density of silicon nitride, where the minimum pressure of said nitrogen is between approx. 20 atmosphere at a sintering temperature of 19G0 ° C and a pressure of approx. 130 atmosphere at a sintering temperature of 2200 ° C.

The process of U.S. Patent No. 4,119,6S0 is similar to that of U.S. Patent No. 4,119,689 except that a magnesium additive is included in the dispersion which comprises silicon nitride and beritium additive. green body sintered by from approx. 1800 ° C for approx. 2200 ° C in a nitrogen sintering atmosphere at a superatmospheric. pressures ranging from a minimum of 10 atmospheres 43 at a sintering temperature of 1800 C to a minimum of 130 atmospheres at a sintering temperature of 2200 ° C. The magnesium additive is selected from the group comprising magnesium, magnesium carbide, magnesium nitride, magnesium cyanide, magnesium fluoride, magnesium silicide, magnesium silicon nitride and mixtures thereof. Magnesium 15

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the additive is used in an amount in which the magnesium component corresponds to from 0.5 wt. 4% by weight of pure magnesium based on the amount of silicon nitride,

The polycrystalline body described in U.S. Patent No. 5,119,689 has a density of between 80% and 100% of the theoretical density of silicon nitride and contains silicon nitride and beryllium in an amount of less than 0.1% by weight to less than 2% by weight of the silicon nitride. The polycrystalline body disclosed in U.S. Patent No. 4,119,690 is similar to that described in U.S. Patent No. 4,119,689 except. it also contains magnesium in pea amount of less than 0.5% by weight dl less than 4.0% by weight of the silicon nitride.

The hot-pressed, polycrystalline silicon nitride bodies can be prepared by methods described in the disclosures of U.S. Patent No. 4,093,687 and U.S. Patent No. 4,122,140, U.S. Patent No. 4,093,687 to a hot-pressed silicon-cesium nitride body. prepared by providing a homogeneous powder dispersion of submicron size of silicon nitride and magnesium silicide in an amount of between 0.5 and 3.0% by weight based on the amount of silicon nitride and hot pressing the dispersion in a nitrogen atmosphere at 1600 ° C to 1850 ° C under a minimum pressure of 138 bar overpressure. The resulting polycrystalline silicon nitride body has a density of 80 to 100 percent of the theoretical density of silicon nitride and contains silicon nitride and magnesium in an amount of from 0.3 wt% to about 9 wt% of the silicon nitride.

! U.S. Patent No. 4,122,140 discloses a hot-pressed poly-crystalline silicon nitride body produced by providing a submicron size powder dispersion containing silicon nitride and a beryllium additive selected from the group consisting of beryllium, beryllium nitride, berylium nitride, -silicon nitride and mixtures thereof, in an amount in which the beryllium component corresponds to from 0.1% to 2% by weight of pure beryllium on the basis of the amount of silicon nitride, and hot pressing the dispersion in a nitrogen atmosphere at from 1600 C to 1850 C under a minimum pressure of 138 bar overpressure. The resulting poly-crystalline silicon nitride body has a density of from approx. 80% to cs. 100% of the theoretical density of silicon nitride and contains silicon nitride and beryllium in an amount of 0.1% by weight to? F) of the silicon nitride

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16

The thickness of the silicon nitride substrate may vary depending on the end use of the composite material provided, but it should be at least sufficiently thick to provide a sufficiently strong support substrate for the polycrystalline diamond body attached thereto. In order to provide sufficiently strong support for the attached poly-crystalline diamond body, the silicon nitride substrate for most applications is preferably at least twice as thick as the fixed poly-crystalline diamond body.

In the arrangement shown in Figure 2, a cell 10 consists of a ', J cup-shaped member 11 (right angled, circular cylindrical wall with bottom).

In the cup-shaped member 11 is placed a disc 12 of a eutectic-containing silicon-rich alloy, a mass 13 of diamond crystals in contact with the silicon-rich alloy 12 and a thick plug 14, e.g. a cylinder of polycrystalline silicon nitride substrate, which cylinder fits snugly into cup-shaped member 11 and acts as a closure therefor.

The copper-lined member 11 is made of a material which is substantially inert under the hot-pressing network, i.e. a material which has no significant deteriorating effect on the properties of the present diamond. Such a material may be a non-meta such as e.g. compressed hexagonal boron nitride, but it is preferably a metal and preferably one of the metals of the group comprising tungsten, yttrium, vanadium, tantalum and molybdenum.

Since this would allow for a mixing or free movement of the contents of the cup-shaped member, there should be no free space in the cup-shaped member left over so that. the content is subjected to the substantially isostatic pressure during the co-pressing step 1 at least substantially in the original location.

The purpose of using size-sorted diamond crystals is to provide a maximum packing of the diamond crystals. Alternatively or additionally, the arrangement shown in Figure 3 is useful for increasing the density or packing of the diamond crystals. The cell 10 is placed on a vibrating plate 16 and is held there under light pressure application (about 3.45 bar) while vibrating the cell 10 to promote and repackage the diamond crystals or particles to fill the gaps and decrease the cavity content to increase the diamond crystal mass. density to over 70% by volume of the diamond mass.

The required compression ratio can be determined by an independent 17

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study done on diamonds of similar size in a fixed-size matrix.

The cue 10 is subjected to a co-pressing step as shown in Figure 4, which cold pressing step is carried out at room-temperature ambient temperature, whereby only sufficient pressure is required to provide a dimensionally stabilized practically isostatic system. The cage 10 is disposed in the cylindrical core of a printing mold 20 and is surrounded by a mass 19 of fine particles (preferably sieve size 0.037 rnm (-400 mesh)) and most preferably 10 with sizes of approx. 2 pm to approx. 20 µm of a pressure transmitting powder medium which, e.g. hexagonal boron nitride and silicon nitride remain practically sintered under the pressure and room temperature conditions of the present process. This pressure transmitting powder or buffer medium provides for the application of approximately 15 or substantially isostatic pressure to the cage 10, whereby the cage 10 and its contents are dimensionally stabilized, i.e. is densified, substantially uniformly, to provide a shaped, substantially isostatic system consisting of the powder-enclosed cehe, wherein the density of the generated compressed crystal layer is over 70 to 20 vol% of the volume of the compressed crystals. The pressure mold 20 (ring 22 and pistons 23, 23a) may be made of tool steel and if desired, the ring 22 may be arranged as shown; a sinter carbide bushing 22a to enable application of pressure up to 13.7S0 bar overpressure. Pressure above 13,790 bar overpressure provides no significant advantage. Within the confines of piston 23, bush 22a and piston 23a, pressure is preferably exerted from the range of 1380 bar overpressure to up to 6.895 bar overpressure and usually up to 3,447 bar overpressure on the pressure transmitting powder medium using the pistons operated in a conventional manner. the applied pressure becomes stable, as is done by conventional powder packing technology.

It can be noted that the specifically applied cold-pressing pressure used can be determined empirically, and pressure over the pressure they produce a conductively stabilized, substantially isostatic system, provides no significant additional densification or dimensional stabilization of cell 10 and its contents.

The present pressure transmitting powder media, e.g. hexagonal boron nitride and silicon nitride, are of such a nature that it results in an approximately hydrostatic effect upon reaction to

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18 a uniaxial applied pressure ten! exerting a substantially isostatic pressure on the entire surface of cell 10. It is assumed that the applied pressure is transmitted substantially undiminished to cell 10. The cold pressing step reduces the size of the gaps, maximizing the presence of capillary size pores in the diman mass, and it also produces the required diamond crystal density of over 70% by volume of the diamond mass. This reduction of the pore void also decreases the final content of non-diamond material in the diamond mass and provides tens, for effective bonding to each other appropriately placed, side by side, crystal-to-crystal! areas.

At the end of the coasting step, the density of the compressed diamond crystals * cell 10 should be over 70% by volume of the volume of the crystals. The density of the compacted I5 diamond crystal mass layer is pi from 71% by volume to not more than 95% by volume and often from 75% by volume to SO% by volume of the diamond crystals. The greater the crystal count, the less the amount of non-diamond matrices occurring between the crystals will be, resulting in a relatively tougher 23 diamond body.

The essentially iso-static pursuits produced during the co-pressing step. 21, comprising: ·· the powder enclosed container is subjected to a hot pressing step thereby subjected to hot pressing temperature and pressure simultaneously, cb. When the coiding pressing step is completed, one of the pistons 23, 23a is withdrawn, and the resulting consolidated, substantially isostatic shaped system 21 is forced out of casing 22a and then into a hole of identical diameter in a graphite form 30, so that the transferred system 21 is now enclosed by the walls of the hole 31 30 between two graphite pistons 32, 32a. The graphite mold 30 is provided with a thermocouple 33 to provide an indication of the temperature applied to the dimensionally stabilized, substantially isostatic system 21. The mold 30, with the substantially isostatic system 21, is enclosed on the aforementioned 35 way, is placed in a conventional hot-pressing oven not shown. The furnace chamber is evacuated or evacuated at least almost completely, causing evacuation of the system 21 including the cell 10, thereby providing the system 21 and the cell 10 with an almost complete vacuum in which the hot pressing step may be effected.

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fed. However, at this point, nitrogen or hydrogen or an inert gas such as e.g. argon, into the furnace chamber to provide a suitable hot pressing atmosphere in the furnace chamber as well! as in the system 21, including the interior of the cell 10. While the pistons 32, 32a apply a uniaxial pressure, namely the hot pressing pressure, on the system 21. its temperature is raised to a value at which the silicon-rich alloy disk 12 produces liquid silicon-rich penetration alloy.

During the hot pressing step, the hot pressing temperature must be reached 10 quickly and maintained for generally at least 1 minute at this value below the hot pressing pressure to ensure satisfactory penetration through the cavities of the diamond crystal mass. Generally, a hot pressing time period of from about 1 minute to about 5 minutes is satisfactory. Since the transformation of diamond ten! free Non-15 diamond carbon large seal depends on time and temperature, ie. the higher the temperature and the longer the time at such a temperature, the more likely the conversion to free non-diamond carbon, the hot pressing step must be carried out within 5% by volume, of the diamond converted to free non-diamond carbon, and this can be determined empirically. Convert- £ 0 nesse of 5% by volume or more of the diamond ten! free Non-diamond carbon probably leads to us being a fr; non-diamond carbone phase back into the final product, which we; have a significant detrimental effect on its mechanical properties.

During the hot-pressing step, the application of the hot-pressing force on the liquid, penetrating, silicon-rich alloy leads to breaking of the resistant interface layer or interface layer, which is mainly composed of oxide or carbide, usually formed between the liquid-rich, silicon-rich and silicon-rich alloy. thereby exposing the capillary pore system to the silicon-rich alloy, after which penetration by hair-tube action takes place. Studies have shown that penetration of silicon-rich alloy into the diamond mass will not occur unless during the entire hot pressing, and while the silicon-rich alloy is liquid, a pressure sufficient to break the slag is maintained and maintained on system 21.

As the liquid, silicon-rich alloy, during hot pressing, seeps and flows through the diamond mass and comes into contact with the substrate, it encapsulates the surfaces of the compressed diamond crystals and reacts with the diamond surfaces or possibly look free

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20 non-diamond carbon, optionally formed, thereby producing a carbide which is at least for a large day and usually predominantly silicon carbide. During hot pressing, this penetration alloy also fills the interface between the contact surfaces of the polycrystalline diamond body and the substrate, resulting in the formation of a strong bond in situ. The product produced is a well-connected integral composite material. The penetrating alloy can also! penetrate or diffuse into the substrate.

It is during this hot pressing step that it is particularly important to maintain essentially isostatic conditions such that when the alloy of the silicon-rich state is converted to the liquid stage, this liquid will not be able to pass between the masses. 13 and the cup-shaped organ Π:, y escape substantially but will be forced ten! to move through the entire diamond crystal mass 13.

When the hot pressing step is completed, at least a drawable pressure must be maintained while cooling the hot pressed system 21 tb. that the hot-pressed cell 10 is subjected to a substantial isostal pressure sufficiently large to maintain its 20-dimensional stability. The hot-pressed system?: 'Is preferably allowed to cool down to room temperature. The hot pressed mold is then removed from the system and the generated composite material 36 is uncovered and comprises a poly crystalline diamond body 13a which is bonded in situ directly to a substrate 14a. Optionally, non-penetrating metal from the protective container and optionally extruded surplus-site alloy on the outer surfaces of the composite material can be removed by conventional methods, such as by grinding. When the present process is carried out with the components as layers having all the same extent, the composite piece produced can have many different forms, such as e.g. a disc, a cube or a rectangle, a rod or rod, and may have a flat surface of bound diamonds.

When the present process is carried out with the silicon-rich alloy present as a tube or cylinder having a through-core or through-hole, and when the substrate is rod-shaped and located centrally in the core of the tube, and the enclosing space between the silicon alloy tube and the substrate is packed with diamond crystals, the resulting composite material is obtained in the form of a circular rod.

21

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The present composite material comprises a polycrystalline diamond body which is integrally bonded to a polycrystalline silicon carbide substrate or a silicon nitride body by a bond formed in situ.

The adhered polycrystalline diamond body of the present composite material comprises diamond crystals which are strongly bonded to each other by a silicon atom-containing binder, the size of the diamond crystals being from about 1 µm to about 1000 µm, the density of said diamond crystals being from at least 10 70% by volume ten! maximum 90% by volume and often approx. 89% by volume of the polycrystalline diamond body, where the silicon atomic binder is present, said diamond body in an amount of up to 30% by volume of the body, wherein the bonding medium is substantially uniformly distributed throughout the polychrysalinic diamond body. the! or surface of said non-contact medium which contacts the surfaces of the bound diamonds. At least to a greater extent, silicon carbide, i.e. that over 50% by volume of the de! if the surface of the binder that is in direct contact with the surfaces of the diarosntcry falls, is silicon-20 carbide- Preferably they are! or that surface of said binder medium which is in contact with the surfaces of the bonded diamond crystals, at least for. greater part of silicon carbide, viz. at least 85% by volume and preferably 100% by volume of the binder that is in direct contact with ae bonded diamond crystal surfaces is silicon carbide. The composition of the present composite material is pore-ridden or at least practically pore-free.

In the composite, the density of the polycrystalline silicon nitride substrate is between 80% and 100% of the theoretical density of 59 silicon nitride, and it contains silicon nitride in at least 90% by weight of the body and does not contain any components having any significant adverse effect on the mechanical properties of the composite.

In the composite, the density of the polycrystalline silicon carbide substrate pi is between 85% and 100% of the theoretical density of silicon carbide and the polycrystalline silicon carbide substrate contains silicon carbide in an amount of at least 90% by weight of the body and does not contain any constituents, p in the mechanical properties of the composite material.

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22 In the composite material, the binder extends in the interface between the polycrystalline diamond body and the silicon carbide or silicon nitride substrate of the polycrystalline diamond body to contact the substrate, filling at least substantially all of the pores in the entire interface. all essentially pore-free, we! say that provided that such voids or pores are small (less than 0.5 µm) and sufficiently uniformly distributed throughout the interface so that they have no significant detrimental effect on the strong bond in the interface, the interface may contain voids or pores in an amount of pi less than 1% by volume of the total volume of the interface. The void or pore content of the interface can be determined by metal I standard graphical methods such as e.g. optical examination of a cross section of the composite material. Generally, the distribution and thickness of the binder medium in the interface is substantially the same as the distribution and thickness of the binder medium in the poly-crystalline diamond body of the composite. Considering a polished cross section of the composite material, the average thickness of the binder in the interface will be substantially as the average thickness of the binder between the 20 contact-forming diamond crystals in the polycrystalline diamond body of the composite. Similarly, the maximum thickness of the binder in the interface p in a polished cross section of the composite will be practically equivalent to the thickness of the binder between the largest contact forming diamond crystals in the polycrystalline diamond body of the composite. Alternatively, the maximum thickness of the binder at the interface can be stated as approx. 50% of the size of the largest diamond crystals in the diamond crystalline diamond body when measured in size along their longest dimension. The silicon carbide substrate may also contain binder provided by penetration or diffusion therein of the penetration alloy during hot pressing.

The silicon atom-containing binder always contains silicon carbide. In one embodiment, the binder contains silicon carbide and metal silicide. In another embodiment, the binder contains silicon carbide, metal silicon and free silicon. In yet another embodiment, the binder contains silicon carbide, metal silicon and metal carbide. In a further embodiment, the binder contains silicon carbide, metal silicon, metal carbide and free silicon. In yet another embodiment, the binder contains silicon carbide, metal carbide and free silicon.

23

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The metal component of the metal silicide and metal carbide in the binder is provided by the alloy metal or metals present in the penetrating alloy.

The metal component of the metal silicide in the binder is preferably selected from the group consisting of cobalt, chromium, iron, hafnium, manganese, rhenium, rhodium, ruthenium, tantalum, thorium, titanium, uranium, vanadium, tungsten, yttrium, zirconium and their alloys.

The metal component of the metal carbide in the binder is a strong carbide forming a stable carbide and is preferably selected from the group consisting of chromium, hafnium, titanium, zirconium, tantalum, vanadium, tungsten, molybdenum and their alloys.

The optional proportion of free silicon and silicon carbide in the binder in the adhered polycrystalline diamond body may vary depending upon the degree of reaction between the surfaces of the diamond crystals and the penetrating, silicon-rich alloy and the reaction between free non-diamond carbon and penetrating silicon-rich alloy.

All else being equal, the specific proportion of silicon carbide present in the binder in the adhered polycrystalline diamond body depends essentially on the specific hot pressing temperature used and the residence time at that temperature. In particular, the proportion of silicon carbide increases, while the proportion of free silicon decreases or decreases to an undetectable amount as time and / or temperature increases. The preparation of a body of bonded diamond crystals having a certain desired silicon carbide content, e.g. to achieve certain desirable properties can be determined empirically.

The binder in the adhered polycrystalline diamond body will always contain at least a detectable amount of silicon carbide and at least a detectable amount of silicon and / or carbide of the alloy metal present in the penetrating alloy. The metal silicide is usually present, depending on the particular penetrating alloy used, as a disilicide. In addition, the binder may contain at least a detectable amount of free silicon. By a detectable amount of silicon carbide, metal silicide, metal csrbid or free silicon is understood herein an amount detectable by selective surface diffraction analysis by transmission electron microscopy of a thin section of the diamond body. Generally, however, the binder in the diamond body contains silicon carbide in an amount of from 1% to 25% by volume of the polycrystalline diamond body and usually metal silicide in at least one

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24, and often in a minimum amount of about 0.1% by volume of the polycrystalline diamond body. The specific amount of metal silicide present depends essentially on the composition of the penetrating silicon alloy.

The metal silicides are hard and, moreover, often, such as, for example, rhenium, have a smaller coefficient of thermal expansion than the metals or in some cases less than diamond, which is a desirable property for a phase in a polycrystalline diamond body. The amount of silicon carbide and free silicon present depends to a large extent on the composition of the penetrating silicon-rich alloy and the degree of reaction between the penetrating silicon-rich alloy and diamond or non-diamond carbon. The particular amount of metal carbide present depends largely on the composition of the penetrating silicon-rich alloy.

Selective surface diffraction analysis by transmission electron microscopy of a thin section of the present composite shows that the part of the binder that contacts the surfaces of the bound diamonds is at least a major part of silicon carbide.

The present adhered body of bound diamond cruciferous is void or pore-free or at least substantially pore-free, the we! say that, provided that the voids or pores are small (less than 0.5 µm) and sufficiently uniform throughout the body so that they have no significant detrimental effect on its mechanical properties, it may contain voids or pores in a amount less than 1% by volume of the body. The void or pore content of the present body may be determined by metal log raf in standard methods such as e.g. optical examination of a polished cross section of the body.

30 The present adhered diamond body also contains no non-diamond carbon phase, as it contains no free non-diamond carbon phase in amounts detectable by X-ray diffraction analysis.

A particularly advantageous feature of the present invention is that the polycrystalline diamond body of the present composite material can be provided in many different sizes and shapes.

Eg. For example, the adhered diamond body may be as wide or as long as 25 mm or more. Polycrystalline diamond bodies of 25 mm or more in length and with the present diamond density can, 25

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due to the limitations of the device necessary to withstand the high pressure and temperature requirements in the required time, in practice, neither are manufactured nor at all produced by processes utilizing the ultra-high pressures and temperatures 5 in the diamond stability region, since the manufacturing apparatus becomes so complex and massive that its capacity becomes limited. On the other hand, the present adhered polycrystalline diamond body may be as small or as thin as desired, but it will always answer ten! more than one layer of diamond crystals.

The present composite material is very useful as an abrasive, cutting tool, nozzle or other abrasion resistant component.

The invention is further illustrated by the following examples, the method, unless otherwise stated, was as follows:

IF LI CIUMCARB IDSUBSTRATE

Hexagonaite boron nitride powders of fine particle size, e.g. sizes of from about 2 µm to about 20 µm were used as the pressure transmitting powder medium.

The polycrystalline silicon carbide substrate was in the form of a disc about 3.05 mm thick.

The apparatus used was practically similar to that shown in Figures 4 and 5.

Cold pressing of the batch was carried out at room temperature as shown in Figure 4 at up to about 5.5 kilobars overpressure.

The amount of penetration alloy was sufficient to completely penetrate the compacted diamond mass and make contact with the contact surface of the substrate and fill the pores in the interface.

The penetrating alloy was a eutectic-containing, silicon-rich alloy.

The density indicated herein for the polycrystalline silicon carbide body used as the substrate is the relative density calculated from the theoretical density of 3.21 g / cm for silicon carbide.

All the polycrystalline silicon carbide bodies, sintered as well as hot pressed used as substrates, were of substantially the same composition and contained silicon carbide, 1-2% by weight boron based on the silicon carbide and less than

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26 1% by weight submicron, free carbon, calculated on the basis of the silicon carbide. The carbon was available in submicron size particle form.

The diamond powder used was of particle size from 1 µm to about 60 µm, of which at least 40% by weight of the diamond powder was less than 10 µm.

Where a particular diamond density is given as the volume percentage of the polycrystalline diamond body, this was determined by the standard point count technique (using a photographer) of a polished surface enlarged 10,690 times and the surface area examined , was sufficiently large to represent the whole body microstructure.

Where the diamond velocity is indicated as an interval of more than 70% by volume to less than 90% by volume of the polycrystalline diamond body, this range is based on experience, results from 15 corresponding workflows, in particular workflows in which only the polycrystalline diamond body was made, and on the appearance of the adhered polycrystalline body taken as a whole and in addition to the volume of the uncovered purified polycrystalline diamond agent of the composite material, compared to the volume of the starting diamond powder, assuming that less than 5% by volume of diamond powder was not converted to a phase of diamond free carbon.

I lose! In Examples 1 to 5, a cup-shaped laminated denture member with a zirconium casing was used, and a cast alloy in disc form of the composition and thickness indicated and of substantially the same diameter as the zirconium casing was placed in the zirconium casing at the bottom of it. cup-shaped organ. The specified amount of diamond powder was packed on top of the disc. Finally, the indicated polycrystalline silicon carbide disk placed on top of 30 diamond powdered to form a plug in the cup-shaped member as shown at 14 in Figure 2.

The resulting cup-shaped cup-shaped body, as shown in Figure 4, was then packed in hexagonal boron nitride powder, and the entire batch was pressed at room temperature, ie. cold pressed, in a steel matrix to about 5.5 kilobar overpressure in such a manner that the cup-shaped member and contents were subjected to substantially isostatic pressure until the pressure was stabilized, thereby providing a dimensionally stabilized, shaped, practical taken isostatic system comprising the powder-enclosed, plugged cup-shaped member.

27

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From previous experiments it was known that the resulting pressed collection of elements, viz. the resulting shaped, substantially isostatic system comprising the powder-enclosed, plugged cup-shaped member had a diamond crystal density greater than 75% by volume of the compacted diamond mass.

The resulting pressed assembly of elements 21 comprising the powder-enclosed, plugged cup-shaped member was then hot-pressed, i.e. it was pushed into a graphite mold of the same diameter size as the style matrix as shown in Figure 5, and the graphite mold was placed in an induction heater. The interior of the plugged cup-shaped member was evacuated and a nitrogen atmosphere was introduced therein by evacuation of the heater ten! about 1,330 Pa (10 torr) before being refilled with nitrogen. A pressure of about 345 bar overpressure was applied to the pressed assembly of elements 21 and maintained on it by the graphite matrix which was then heated by the induction heater at such a rate that the given maximum heat pressing temperature was reached in about 5 to 7 minutes. As the assembly of elements warmed, the pressure increased to the given maximum heat compressive pressure due to the expansion of the system.

At the given temperature at which a grinding began or progressed, the piston sank and the pressure dropped to about 345 bar overpressure, indicating that the alloy had become liquid and continued to seep through the compressed diamond mass. Pressure. was then raised again to the given maximum hot pressing pressure, and kept at this value at the given maximum hot pressing temperature Ϊ 1 minute to ensure complete penetration of the alloy into the small capillary cavities of the compressed diamond mass. The energy supply was then interrupted, but no further pressure was applied. This produced a fixed pressure at high temperature but reduced pressure at low temperature, thereby providing adequate geometric stability, ie. it retained the dimensions of the hot pressed assembly of elements until it was sufficiently cold to handle.

The resulting composite material was exposed by cutting metal, i.e. the cup-shaped molybdenum member and the zirconium sleeve, and excess alloy on the outer surfaces of the composite were sanded or sandblasted away.

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28

The resulting purified integral composite matte body was in the form of a substantially smooth disk having in thicknesses of Examples 1 to 3 approximately 4.95 mm and in Example 4 approximately 4.06 mm.

In Examples 6 and 7 of Table I, no metallic container, liner or substrate was used, but the equipment used was substantially similar to that shown in Figures 4 and 5. In carrying out Examples 6 and 7 For example, the hexagonal boron nitride powder was packed in the matrix of Figure 4 and a cylinder used as a mold was pressed into the powder. The cylinder was made of sintered cemented metal carbide and was about 8.89 mm in diameter and 6.35 mm in thickness. The axis of the cylinder is brought about to align approximately with the center axis of the matrix.

After the cylinder was introduced into the powder, an additional 15 hexagonal boron nitride powders were placed in the matrix to completely cover the cylinder and the resulting powder-enclosed cylinder was pressed at room temperature under a pressure of 3.45 kilobar overpressure. The plunger 23a was then retracted and the plunger 23 was used to push the resulting pressed powder-wrapped cylinder partially 20 out of the die.

They exposed it! of the pressed powder was removed so that the cylinder was left partially exposed. The cylinder was then removed leaving the cavity it had extruded therein. In Examples 6 and 7, a cast alloy disc of the given composition and thickness and having substantially the same diameter as the inner diameter of the cavity was placed at the bottom of the cavity. A diamond powder layer of the given size, quantity and thickness was packed on top of the alloy.

A disc of hot pressed hexagonal boron nitride powder of approximately the same diamonds as the inner diameter of the cavity was placed in the housing above the diamond powder as a plug to ensure that the surface of the resulting polycrystalline diamond body would become flat.

The entire mass was then pushed into the center of the die by means of the plunger 23a, which was then withdrawn. An additional amount of hexagonal boron nitride powder was added to the matrix to cover the hot pressed disc of hexagonal boron nitride, thereby enclosing the cavity and contents of hexagonal boron nitride, as illustrated in Figure 4. The resulting charge was then pressed at room temperature, i. cold pressed, in the steel matrix under a pressure of 5.5 ktlobar 29

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overpressure as shown in Figure 4, subjecting the cavity and its contents to a substantially isostatic pressure until the pressure stabilized, thereby providing a dimensionally stabilized, shaped, practically isostatic system comprising the powder-enclosed cavity 5 and the contents. From previous experiments, it was known that the diamond crystal density in the produced pressed collection of elements, ie. in the formed, substantially isostatic system comprising the powder-enclosed cavity and contents, was over 75% by volume of the compacted diamond mass.

The resulting pressed assembly of elements comprising the powder-encased cavity and contents approximately equal to 21 except that no meta container was used was then hot pressed, i.e. it was pushed into a graphite shape of the same diameter size as the style matrix, as shown in Figure 5, and placed in an induction heater. The interior of the cavity was evacuated and a nitrogen atmosphere was initiated therein, evacuating the heater to about 1,330 Pa (10 torr) before being refilled with liquid dry nitrogen. A pressure of about 345 bar overpressure was released ten! the pressed assembly of elements and maintained thereon by the graphite matrix, which was then heated by the induction heater at such a rate that it reached the given maximum heat compression temperature in about 5 to 7 minutes. As the assembly of elements was heated, the pressure increased to the given maximum heat compressive pressure due to the expansion of the entire system.

At the given temperature at which infiltration begins or progresses, the piston sank and the pressure dropped to about 345 bar overpressure, indicating that the given alloy had melted and become liquid and had penetrated the diamond mass. The pressure was then raised, ten! it was again equal to the given maximum hot compress pressure at which value it was held for 1 minute to ensure complete penetration of the alloy into the smaller capillary cavities of the compressed diamond mass. The energy supply was then interrupted, but no further pressure was applied. This provided a fixed pressure 35 at high temperature but lower pressure at lower temperature, thereby providing adequate geometric stability. At room temperature, the polycrystalline diamond body produced was uncovered. The plug did not attach to the diamond body. After removal of hexagonal boron nitride powder surface shells and excess alloy by grinding,

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30 and sandblasting had the resulting polycrystalline integral diamond body disc shape of the given thickness.

In Table I, the hot pressing temperature at which penetration begins is the temperature at which the alloy is liquid and continues to seep through the compressed diamond mass.

The given maximum hot pressing temperature and maximum hot pressing pressure were maintained simultaneously for 1 minute to ensure complete penetration into the smaller capillary cavities Ϊ the compressed diamond mass.

The X-ray diffraction analyzes of Examples 6 and 7 listed in Table I were performed on the polycrystalline diamond body in crushed form.

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DK 153536 B

33 in Examples 1 to 5, the interface of each composite material disc between the adhered polymeric crystal diamond body and the silicon carbide substrate could not be detected. Each composite material appeared to be a continuous structure throughout its thickness, and only the grain size in the diamond part separated it from the substrate. The outer surface of each adhered poly crystal lens diamond body appeared to be well penetrated by binder which appeared to be evenly distributed. The diamonds seemed to be well bonded to each other.

The adhered polycrystalline diamond body in the composite materials of Examples 1 to 4 had a diamond density greater than 70% by volume but less than 90% by volume of the polycrystalline body.

The diamond surface of the composite material of Example 5 was polished on a cast iron diamond polishing apparatus. Examination of the polished 15 facade showed no rows of holes formed by extracting diamond fragments, showing the strong bond therein. The diamond crystal density was about 73% by volume of the adhered polycrystalline diamond body.

In Examples 6 and 7, the polycrystalline diamond bodies were well penetrated and well bonded. Using a hammer and a wedge, each disc, i.e. the polycrystalline diamond body, so to speak, fractured midway and the bridesmaids were examined optically enlarged about 100 times under a microscope. Examination of these fracture surfaces revealed that they were pore-free, that the binder was uniformly distributed throughout the body, and that the fractures were transgranular rather than intergranular, ie. that each body was fractured through the diamond grains rather than along the grain boundaries. This shows that the binder was strongly adherent and was as strong as the diamond grains or crystals themselves.

The diamond density of the disc in Example 6 was over 70% by volume but less than 90% by volume of the body.

A fracture surface of the disc of Example 7 was polished on a cast-diamond diamond polisher, and examination of the polished surface showed no hollow rows formed by extracting diamond fragments, showing the strong bond therein. The diamond crystal density was about 80% by volume of the polycrystalline diamond body.

η 34

DK 1535S6B

EXAMPLE 8

The composite material produced in Example 1 was rated as a cutting tool. The exposed surface of the polycrystalline diamond body in the composite was sanded with a diamond grinding wheel to smooth it and provide a sharp cutting edge. The composite material substrate was then attached to a tool holder.

One of the cutting edges was evaluated on a lathe turning from Jackfork Sandstone at a feed rate per minute. rotation of 0.127 mm and a cutting depth of 0.508 mm.

At the cutting speed of 49.8 cm / s, the wear rate was determined to be -6 3 to be 0.0210 X 10 cm / s. Another portion of the cutting edge was assessed at the cutting speed of 140.2 cm / s and determined to have —6 3 a wear rate of 0.145 x 10 cm / s. Yet another portion of the cutting edge was assessed at the cutting speed of 147.3 cm / s and was determined to have a wear rate of 0.3988 x 10 cm / s.

The composite material was removed from the tool holder, and examination of the interface between the diamond body and the substrate revealed that it had not been affected by these studies in machining.

EXAMPLE 9

The method used in this example was similar to the method described in Example 8 except that the composite material used was the one prepared in Example 2.

A portion of the cutting edge had a wear rate of 0.0554 X 10 3 cm3 / s at the cutting speed of 55.88 cm / s. Another portion of the cutting edge had a wear rate of 0.4042 X 10 3 cm3 / s at the cutting speed of 162.6 cm / s.

Examination of the composite after the machining process showed that the interface between the polycrystalline diamond body and the silicon carbide substrate was not affected by these machining machining tests.

35

DK 153536 B

EXAMPLE 10

The method used in this example was similar to the method described in Example 8 except that the coposite 5 according to Example 3 was used.

Part of the cutting edge exhibited a wear rate of 0.06391 X 10 cm / s at the cutting speed of “55.88 cm / s. Another portion of the cutting edge exhibited a wear rate of 0.5053 X 10® cm3 / s at the cutting speed of 162.6 cm / s.

Examination of the composite material after the machining machining showed that the interface between the polycrystalline diamond body and the silicon carbide substrate was not affected by these machining machining tests.

EXAMPLE 11

The method used in this example was similar to the method described in Example 8 except that the composite material of Example 4 was used.

After 4 minutes of successful cutting at the cutting speed 49.8 20 cm / s (98 surface feet per minute), small pieces of the cutting edge broke. Using another part of the cutting edge, after 6 minutes of successful cutting at the cutting speed, 142.2 cm / s of small pieces of the cutting edge broke. It is believed that the fracture at the cutting edge was due to the fact that the hot pressing temperatures 25 had not been sufficiently high to achieve complete penetration into the small capillary cavities of the polycrystalline diamond mass during the hot pressing. Comparison with Example 7 of Table I shows that the higher hot pressing temperatures provide a well-penetrated and well bonded polycrystalline diamond body.

EXAMPLE 12

The process for preparing the composite material was substantially similar to the procedure described in Example 2 except that 260 mg of the silicon chromium alloy was used and the alloy disc was 1,270 mm thick.

In addition, 250 mg of diamond powder was used in which 60% by weight was of sizes from 53 to 62 µm, 30% by weight was between 8 and 22 µm and 10% by weight was between 1 and approx. 5 pm. The diamond powder was packed to an approximate thickness of about 1.397 mm. In addition, a cup-shaped zirconium member with a zirconium liner was used.

The maximum hot pressing pressure was about 0.9 kilobar overpressure and the hot pressing temperature ranged from about 1,250 ° C at the onset of the pouring to a maximum hot pressing temperature of about 1,500 ° C. The composite material was exposed in the same manner as in Example 2 and took the form of a practically smooth slab having a thickness of approx. 1.52 mm.

The silicon carbide substrate was sanded by the composite material and the resulting polycrystalline diamond body was subjected to a heat stability study. More specifically, it was heated in air to a temperature of 900 ° C, which was the limit temperature of the oven. As it heated, its thermal length expansion coefficient was determined at temperatures from 100 ° C to 900 ° C. At 900 ° C the energy supply was interrupted.

The examination results and the visual examination of the sample, ie. the post crystalline diamond body after examination showed that there was no sudden length change for the sample throughout the heating cycle and there was no evidence of permanent damage to the sample caused by the heating cycle.

EXAMPLE 13

The method used in this example was substantially similar to that described in Example 2 except that the silicon wafer was used in a cup-shaped zirconium member with a zirconium liner to form a silicon-rich zirconium alloy in situ.

Six composite materials were prepared. In the preparation of three of the composite materials, a diamond powder was used, in which 60% by weight was of sizes from 53 to 62 µm, 30% by weight was 30 p | from 8 to 22 pm and 10% by weight was from 1 to about 5 pm.

The other three composite materials were prepared using a diamond powder of from 1 to 10 times. 60 µm in size, of which at least 40% by weight was less than 10 µm in size.

The maximum hot pressing pressure was about 0.9 kilobar overpressure 35 (13,000 psi), and the hot pressing temperature ranged from approx. 1,340 ° C, which is the temperature at which the infiltration progresses, showing that the silicon-rich zirconium alloy had been formed in situ and had become liquid, to a maximum hot-pressing temperature of about 1,500 ° C.

37 ru / ή ί - 7 Γ ~ ~ 7

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Each composite material blank was exposed to essentially the same mite as in Example 2, and each blank was in the form of a slab.

The top and cylinder faces of the adhered polycrystalline diamond body in all six composite materials were surface grinded. The difficulty of grinding these composite materials with a diamond sieve wheel showed that the abrasion resistance of these adhered diamond bodies could be compared to commercially available polycrystalline diamond products.

The three composite materials made with the diamond powder, ranging from 1 to 60 microns in size, had insufficiently mixed aggregates of diamond powder less than 2 microns in size, and an examination of the abrasive edges of the polycrystalline body showed incomplete penetration of the alloy into these 15 aggregates, but the rest of the cut diamond area was well connected.

Optical examination of the composite material revealed no detectable defects or any discernibly different interlayer between the silicon carbide substrate and the diamond layer. Four of the composite materials 20 were broken so that the internal structure could be observed. Optical examination of the fracture surfaces revealed no visible interlayer or visible defects at the interface between the silicon carbide substrate and the adhered polycrystalline diamond layer.

The structural continuity of the substrate-diamond layer interface was excellent and only the grain size difference between diamond and silicon carbide enabled recognition of the boundary line between the substrate and diamond layers.

Two of the composite materials were rated as cutting tools by turning a very abrasive, sand-filled rubber rod. The cutting parameters were: cutting depth 0.762 mm, feed rate per speed 0.13 mm, and cutting speed 304.8 cm / s. After cutting for 16 minutes and 22 seconds, both tool pieces showed an approx. 0.13 mm, uniform side wear, which showed that the abrasion resistance of the cutting edge was excellent.

EXAMPLE 14

The composite material of Example 1 was fractured practically in the middle by means of a hammer and a wedge, and the fracture surfaces were examined at a magnification of approx. 100 X under a microscope. Examination of the fracture surfaces showed that the polycrystal - -r? ------- 38

DK 153536 B

both the body and the composite material interface were pore-free, that the binder was distributed uniformly throughout the diamond body and that the fracture was transgranular rather than intergranular, i.e., the fracture occurred through the diamond grains rather than along the grain boundaries. This shows that the binder was strongly adherent and was as strong as the diamond grains or crystals themselves. Also, no visible interlayer or visible defects could be detected in the interface between the silicon carbide substrate and the adhered poly crystal lined diamond layer. The fracture surface of the composite material appeared to have a continuous structure, and only the difference in grain size between the diamond and the strongly adhered substrate allowed recognition of the boundary line between the substrate and the adhered polycrystalline diamond body.

The fracture surface perpendicular to the composite was polished on a cast iron diamond polishing apparatus. Optical examination of the polished cross-sectional façade shown in Figure 7 did not show any holes formed by extraction of diamond fragments, showing the strong bond therein. The poly crystalline diamond body is shown in the upper part and substrate in the lower part of Figure 7, and the interface therebetween 20 can be skewed by the difference in crystal structure between the diamond body and the substrate. The density of the diamond crystals was about 71% by volume of the polycrystalline body in Figure 7.

silicon nitride substrate

25 Hexagonal boron nitride powder of fine particle size, that is, sizes of approx. 2 pm to approx. 20 µm, was used as pressure transmitting powder medium.

The polycrystalline silicon nitride substrate was in the form of a disc which in Examples 16 and 17 had a thickness of approx. 3.18 mm 30 and in Examples 19 and 20 a thickness of approx. 2.54 mm. The substrate was a commercially available hot-pressed material with a density above 99%, ie. that it was almost 100% dense, and comprised as a percentage by weight of the hot pressed silicon nitride body, ½% NlgO, ca. \% Fe, ca. 1/200% metallic impurities such as Ca, Al and 35 Cr, 2% free Si and 1% SiC while the remainder was silicon nitride.

The equipment used was essentially similar to that shown in Figures 4 and 5.

DK 153536 B

39

Cold pressing of the batch was carried out at room temperature as shown in Figure 4 at up to approx. 5.5 kilobar overpressure, and in the resulting pressed assembly of elements, the diamond crystal density accounted for over 75% by volume of the compacted diamond mass.

The amount of penetrating alloy was sufficient to fully permeate the compacted diamond mass and make contact with the contact surface of the substrate as well as fill the pores in the interface.

The penetrating alloy was a eutectic-containing, silicon-containing alloy.

The density indicated herein for the polycrystalline silicon nitride body used as a substrate is the relative density calculated on the basis of the theoretical density of silicon nitride which is 3.18 g / cm 2.

Fracturing of a composite material or polycrystalline diamond body was performed with a hammer and wedge.

Optical examination was performed at about 100X magnification under a microscope.

Polishing was done on a cast iron diamond polisher.

2S) Where a particular diamond density is given as the volume percentage of the polycrystalline diamond body, this was determined by the standard point counting technique using a micrograph of a powdered surface enlarged 690 times and the surface area examined was sufficiently large to represent the entire the microstructure of the body.

Where the diamond density is indicated as an interval greater than 70% by volume but less than 90% by volume of the polycrystalline diamond body, this range is based on experience, results from similar experiments, especially experiments where the polycrystalline dia-3Φ mantie body was produced alone, and the adherent polycrystalline the appearance of the diamond body as a whole, and in addition to the volume of the uncovered, purified, polycrystalline diamond composition of the composite material compared to the volume of the starting diamond powder reef, provided that less than 5% by volume of the diamond powder was converted to a phase of free non-diamond.

in Examples 15 and 16, the penetrating silicon-rich alloy was an in situ silicon and zirconium alloy.

EXAMPLE 15 [This example prepared a polycrystalline diamond body without substrate.

A 330 mg cast silicon wafer was placed in a zirconium sleeve in a cup-shaped molybdenum member.

About 500 mg of fine diamond powder with particle sizes ranging from 1 μηη to about 60 µm and with at least 40% by weight of the diamond powder less than 10 µm was packed on top of the silicon wafer. A cup-shaped molybdenum member having a slightly larger diameter than the originally used cup-shaped member, ie. the cup-shaped member containing silicon and diamonds is placed over the opening in the original cup-shaped member as a lid.

The resulting container was then packed in hexagonal boron nitride powder, as shown in Figure 4, and the entire batch was pressed at room temperature, ie. cold-pressed, in a style die at approx.

5.5 kilobar overpressure, so that the container and its contents are subjected to substantially isostatic pressure until the pressure is stabilized, thereby providing a dimensionally stabilized, shaped, substantially isostatic system comprising the powder-enclosed container. From previous studies, it was known that the diamond crystal density in the resulting pressed jointing of elements, ie. in the resulting shaped, substantially isostatic system comprising the powder-enclosed container, was over 75% by volume of the compacted diamond mass. The amount of silicon present was approx. 80% by volume of the compacted diamond mass.

The resulting pressed assembly of elements 21 comprising the powder-enclosed container was then hot pressed, i.e. it was pushed into a graphite mold of the same diameter size as the style matrix as shown in Figure 5, and the steel matrix was placed in an induction heater. The interior of the vessel was evacuated and a nitrogen atmosphere was initiated therein, the evaporator being evacuated to about 1,330 Pa (10 torr) before being refilled with nitrogen. A pressure of approx. 345 bar of overpressure was throttled to the pressed assembly of elements 21 and maintained thereon by the graphite matrix, which was then heated by the induction heater to a temperature of 1,500 ° C for about 7 minutes. As the assembly of elements heated, the pressure also increased to about 690 bar overpressure due to system expansion. When the temperature reached about 1,350 ° C, the plunger 23a sank and the pressure dropped to about 345 bar

DK 153536 B

41 overpressure, showing that the silicon-rich zirconium alloy had formed, had become liquid, and had begun to penetrate the compressed diamond mass. The pressure was increased to the maximum heat compressive pressure of 690 bar overpressure, and as the temperature reached 1,500 ° C, 5 biev the assembly of elements maintained at the maximum hot compress temperature of 1,500 ° C under a pressure of 690 bar overpressure for 1 minute to ensure complete penetration of the alloy in the smaller capillary cavities of the compressed diamond mass. The energy supply was then interrupted, but no further pressure was applied. This provided a fixed pressure at high temperature but reduced pressure at low temperature, thereby providing adequate geometric stability, i.e. that it retained the dimensions of the hot pressed assembly of elements until it was sufficiently cold to handle.

The resulting polycrystalline diamond body was exposed by grinding and sandblasting the container metal away, i.e. the cup-shaped molybdenum member and the zirconium sleeve as well as excess silicon on the outside and surfaces of the body.

The resulting polycrystalline integral diamond body had disc shape and was approx. 2,921 mm thick. It seemed to be well-penetrated and bound.

X-ray diffraction analysis of the cleaned surface through which the alloy penetrated showed that it contained diamond, silicon carbide and free silicon, and showed that the silicon carbide and free silicon were present in at least 2% by volume of the body. However, the X-ray diffraction analysis did not reveal any phase of free non-diamond carbon.

An examination of the cross-sectional fracture surfaces of the disc revealed that the fracture was transgranuary rather than intergranuary, ie. that it was fractured through the diamond grains rather than along the grain boundaries. This showed that the binder was strongly binding and that it was as strong as the diamond grains or crystals themselves.

Examination of the fractures showed that they were pore-free and that the binder was uniformly distributed throughout the body.

Examination of the polished cross-sectional surfaces showed no sheath rows formed by extraction of diamond fragments, showing the strong bonding therein and its utility as abrasive.

The density of the diamond crystals was about 81% by volume of the polycrystalline diamond body.

42

DK 153S36B

A photographer! of the polished surface enlarged 690 times showed a white phase. X-ray spectral analysis of this phase showed that it consisted of zirconium and silicon, showing that this phase was zirconium silicide.

EXAMPLE 16! in this example, the composite was prepared using hot pressed polycrystalline silicon nitride as a substrate.

A cast silica wafer weighing 142 mg was placed in a zirconium sleeve in a cap-shaped zirconium member. 270 mg of Diamond Powder, in which 85% by weight of the diamond in size ranged from 53 µη to 62 µm and 15% by weight was about 5 µm in size, was packed on top of the silicon wafer to provide a powder thickness of about 50 µm. 1.5 mm. Instead of the metal cap used in Example 1, hot pressed, polycrystalline silicon nitride was used as a plug, ie. as the plug 14 as shown in Figure 2.

The resulting plugged cup-shaped member was then packed in hexagonal boron nitride powder, as shown in Figure 4, and the entire batch was cold-pressed at room temperature in the same manner as described in Example 1, exposing the tubular cup-shaped member and its contents to a substantially isostatic pressure until the pressure was stabilized, thereby providing a dimensionally stabilized, shaped, substantially isostatic system comprising the powder-enclosed, plugged cup-shaped member. From prior research, it was known that the diamond crystal density in the resulting pressed collection of elements, ie. in the resulting shaped, substantially isostatic system consisting of the powder-enclosed plugged cup-shaped member, was in excess of 75% by volume of the compacted diamond mass. The resulting pressed assembly of elements 21 comprising the powder-enclosed, cup-shaped cup-shaped member was then hot-pressed in the same manner as described in Example 15 except for the exceptions set forth in Table 11.

The resulting composite was exposed by sheath metal and excess silicon on the outer surface and surfaces of the composite being removed by sandblasting and grinding.

Examples 15 and 16 are listed in Table II. In Examples 17, 19 and 20 of Table II, a cast alloy in the form of a disc of the specified composition and thickness and having substantially the same diameter as the given casing was placed in the casing on the bottom of the casing.

DK 153536 B

43 given cup-shaped organ. The given amount of diamond powder was packed on top of the disc. Finally, the given polycrystalline silicon nitride substrate was placed on top of the diamond powder and formed a plug in the cup-shaped member as shown at 14 in Figure 2. The resulting plugged cup-shaped member was then cold-pressed and hot-pressed in the manner described. in Example 2, except for the exceptions listed in Table II. The composite material obtained was exposed in substantially the same manner as described in Example 16.

The resulting purified integral composite material bodies of Examples 16, 17, 19 and 20 took the form of substantially uniform wafers, which in Examples 16 and 17 were approx. 4.7 mm thick and in Examples 19 and 20 approx. 3.8 mm.

In Example 18, a polycrystalline diamond body was made, but no metallic container, casing or substrate was used, but the apparatus used was substantially similar to that shown in Figures 4 and 5. For implementation of Example 18, the hexagonal boron nitride powder was packed in the matrix of Figure 4 and a cylinder used as a mold was pressed into the powder. The cylinder was made of cemented carbide and was about 8.9 mm in diameter and 6.4 mm in thickness. The axis of the cylinder was largely flush with the center axis of the matrix.

After the cylinder was introduced into the powder, an additional amount of hexagonal boron nitride powder was placed in the matrix so that it completely covered the cylinder and the resulting powder-enclosed cylinder was pressed at room temperature under a pressure of 3.5 kilobars overpressure. The plunger 23a was then retracted and the plunger 23 was used to push the provided pressed powder-enclosed cylinder partially out of the die.

The exposed portion of the pressed powder was removed, leaving the cylinder partially exposed. The cylinder was then removed leaving the cavity which it had extruded therein. In Example 18, a cast alloy disc of given composition and thickness substantially equal to the inner diameter of the cavity was placed at the bottom of the cavity. A layer of diamond powder of given size, quantity and thickness was packed on top of the alloy disc.

A disc of hot pressed hexagonal boron nitride powder of about the same diameter as the inner diameter of the cavity was placed in the cavity on top of the diamond powder as a plug to ensure that over

DK 153536B

The surface of the resulting polycrystalline diamond body would become flat.

The entire mass was then pushed into the center of the die by means of the plunger 23a, which was then withdrawn. An additional 5 amount of hexagonal boron nitride powder was placed in the matrix to cover the hot pressed disc of hexagonal boron nitride, causing the cavity and contents to be enclosed by hexagonal boron nitride, as shown in Figure 4. The charge obtained was then pressed at room temperature, i.e. . the coil press, in the die matrix under 10, a pressure of 5.5 kilobar overpressure, as shown in Figure 4, subjecting the cavity and its contents to a substantially isostatic pressure until the pressure stabilized, thereby providing a dimensionally stabilized, shaped, essentially isostatic system comprising the powder-enclosed cavity and contents. From previous 15 studies, it was known that in the provided, substantially isostatic system comprising the powder-enclosed cavity and the content, the diamond crystal density exceeded 75% by volume of the compressed diamond mass.

The pressed assembly of elements comprising the 20 powder-encased cavity and contents substantially identical to 21 except that no meta container was used was then hot-pressed, namely by being pushed into a graphite form with the same diameter size as the steel matrix, as shown in Figure 5, and housed in an induction heater. The interior of the cavity was evacuated and a nitrogen atmosphere was initiated therein, evacuating the heater to approx. 1.330 Pa (10 torr) before being filled again with liquid dry nitrogen. A pressure of about 345 bar overpressure was applied to the pressed assembly of elements and maintained thereon by the graphite matrix, which was then heated by the induction heater at a rate which provided the given maximum hot pressing temperature over about 30 minutes. 5 to 7 minutes. As the assembly of elements warmed, the pressure increased to the given maximum heat compressive pressure due to the entire system expansion.

35 At the given temperature at which penetration began or progressed, the piston sank and the pressure dropped to about 345 bar overpressure, indicating that the given alloy had melted and become liquid and had penetrated into the diamond mass. The pressure was then raised again to the given maximum hot pressing value, 45

DK 153536 B

at which it was kept at the given maximum hot pressing temperature for 1 minute to ensure complete penetration of the alloy into the smaller capillary cavities of the compressed diamond mass. The energy supply was then discontinued, but no further pressure was applied. This provided a fixed pressure at high temperature, but lower pressure at lower temperature, thereby providing adequate geometric stability. The resulting polycrystalline diamond body was exposed at room temperature. The plug did not attach to the diamond body. After removal of surface shells consisting of hexagonal boron nitride powder and excess alloy by grinding and sandblasting, the polycrystalline integral diamond body provided had a slab having the specified thickness.

Table II lists the hot pressing temperature at which the penetration begins, the temperature at which the alloy 15 is flowing and the penetration of the compacted diamond mass continues. The given maximum hot pressing temperature and maximum hot pressing pressure were maintained simultaneously for 1 minute to ensure complete penetration into the smaller capillary cavities of the compressed diamond crystal mass.

20 25 30 35

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Examples 16, 17, 19 and 20 Illustrate the preparation of the present composite material. in these examples, each composite material, by optical examination, appears to be a continuous structure, but the boundary line between the diamond body and the substrate could be detected by the grain size difference and the color difference between the diamond body and the substrate, namely because the silicon nitride substrate was of a darker color than the gray diamond body. . The outer surface of each adhered polycrystalline diamond body appeared to be well penetrated by binder which appeared to be evenly distributed.

10 The diamonds appeared to be well-bonded.

The adhered polycrystalline diamond body in the composite materials of Examples 17 and 18 had a diamond density greater than 70% by volume but less than 90% by volume of the polycrystalline laminate volume.

The diamond face of the composite material of Example 16 was polished and optical examination of the polished surface showed no rows of holes formed by extraction of diamond fragments, showing the strong bond therein. The diamond crystal density was about 71% by volume of the adhered polycrystalline diamond body of Example 20 16.

In Example 18, the polycrystalline diamond body was a well-penetrated, well-bonded, hard disk. The diamond body was split practically in the middle above. Optical examination of the cross-sectional fracture surfaces revealed that they were pore-free, that the binder was evenly distributed throughout the body, and that the fracture was transgranular rather than intergranular, ie. it was broken through the diamond grains rather than along the grain boundaries. This shows that the binder was strongly adherent and was as strong as the diamond grains or crystals themselves.

A fracture surface of the disc of Example 18 was polished and examination of the polished surface showed no rows of creases formed by extraction of diamond fragments, showing the strong bond therein. In Example 18, the diamond crystal density was about 80% by volume of the polycrystalline diamond body.

EXAMPLE 21

The composite material of Example 17 was evaluated as a cutting tool. The exposed surface of the polycrystalline diamond body in the composite material was ground with a diamond grinding wheel

DK 153536 B

49 to smooth it and provide a sharp cutting edge. The substrate of the composite was then clamped in a tool holder.

Part of the cutting edge was assessed on a lathe, 5 which rotated a Jackfork sandstone, at a feed rate of 0.13 mm per second. rotation and a cutting depth of 0.51 mm.

At the cutting speed of 47.8 cm / s, the wear rate was determined to be -6 3 0.060 x 10 cm / s. Another portion of the cutting edge was rated * 6 at the cutting speed 132 cm / s and the wear was determined to be 0.137 x 10 10 cm / s.

The composite material was removed from the tool holder, and an examination of the interface between the diamond body and the substrate revealed that it had not been affected by these machining machining tests.

EXAMPLE 22

The method used in this example was similar to that described in Example 21 except that the composite material prepared in Example 19 was used.

20 A portion of the cutting edge developed at 50.8 cm / s at the cutting speed very small seam marks at 2 minutes cutting time, showing its excellent seam resistance, but the Jackfork sandstone used had a deep cut, and when the composite material was brittle, a small break piece of the cutting edge off.

Examination of the composite material after the cut showed that the interface between the polycrystalline diamond body and the silicon nitride substrate was not affected by these in machining experiments.

EXAMPLE 23

The composite material of Example 20 was fractured practically midway and the cross-sectional fracture surfaces were optically examined. Examination of the fracture surfaces showed that the polycrystalline diamond body and the interface of the composite were pore-free, that the bonding medium was uniformly distributed throughout the body, and that the fracture was transgranular rather than intergranular, ie. that the fracture occurred through the diamond grains rather than along the grain boundaries. This shows that the binder was strongly adherent and was as strong as the seive diamond grains or crystals. Furthermore, no

DK 153536 B

50, some visible interlayer or visible defects appear in the interface between the silicon nitride substrate and the adhered polycrystalline diamond layer. The fracture surface of the composite material appears to have a continuous structure. However, grain size differences between the diamonds and the strongly adhered substrate, as well as the darker color of the substrate, enabled recognition of a boundary line between the substrate and the adhered polycrystalline diamond body.

The fracture cross-section of the composite was polished. Optical examination of the polished cross-sectional surface shown in Figure 7 showed no 10 hollow rows formed by diamond fragment extraction, which showed the strong bond therein. The polycrystalline diamond body is shown in the upper part and the substrate in the lower part of Figure 7, and the interface therebetween can be distinguished due to the difference in crystal structure and color between the diamond body and the substrate. The diamond crystal density was about 75% by volume of the polycrystalline diamond body in Figure 7.

EXAMPLE 24

The composite materials 20 produced in Examples 16, 17 and 19 were divided practically in the middle above and the cross-sectional fractures were examined optically. Examination of the fracture surfaces revealed that the poly-crystalline diamond body and interface of each composite were pore-free, that the binder was evenly distributed throughout the diamond body, and that the fracture was transgranular rather than intergranular, i.e., the fractures existed along the diamond rather than through the diamond. . This shows that the binder was strongly adherent and was as strong as the diamond grains or crystals themselves. In addition, no visible interlayer or visible defects could be detected in the interface between the silicon nitride substrate 30 and the adhered polycrystalline diamond layer. The fracture surface of each composite material appears to have a continuous structure. However, the diamond grain size difference between the diamonds and the strongly adhered substrate, as well as the darker color of the substrate, enabled recognition of the boundary line between the substrate and the adhered polycrystalline diamond body.

The fracture surface of the composite material of Example 19 was polished. Examination of the polished cross-sectional surface showed no hole rows formed by diamond fragment extraction, showing the strong bond therein.

A crochet photograph of the polished surface magnified 690 X showed a 51

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t—- in ι Ο -3000 SZ5 intermediate layer of binder through the interface. Scanning an electron microscopic image of the polished surface magnified 1000 X showed an intermediate layer of binder through the interface which had a maximum thickness of about 3 µm. X-ray spectral analysis of the binder in the interlayer and in the polycrystalline diamond body showed that both contained the same components.

10 15 20 25 30 35

Claims (14)

A composite material comprising a polycrystalline diamond body and a silicon carbide or silicon nitride substrate, characterized in that the polycrystalline diamond body is bonded to a polycrystalline substrate of silicon carbide or silicon nitride into a single piece, wherein the polycrystalline diamond is a polycrystalline diamond, which are firmly bonded to each other with a silicon atom-containing binder comprising silicon carbide and a carbide and / or silicon of a metal component which forms with silicon a silicide, the diamond crystals having a size of from 1 to 1000 µm, the diamond crystal density being from 70% to 90% of the body volume, the silicon-containing binder constitutes up to 30% of the body volume and is at least 15 substantially uniformly distributed within the body, the portion of the binder which contacts the surface of the diamond crystals consists in the at least for the majority of silicon carbide, the diamond body at least i substantially the pore is free, the substrate varies in density from 85% to 100% of the theoretical density of silicon carbide or from 80% to 100% of the theoretical density of silicon nitride and contains silicon carbide or silicon nitride in an amount of at least 90% of the weight of the substrate. , the polycrystalline diamond body forms an interface with the silicon carbide or silicon nitride substrate, and the binder extends from the crystalline diamond body to the substrate's contact surface 25 and at least substantially fills the pores of the interface, so that the interface is at least substantially free. Composite material according to claim 1, characterized in that the binder also contains free silicon. Composite material according to claim 1 or 2, characterized in that the density of the diamond crystals is from 70% to 89% of the volume of the diamond body. Composite material according to any of claims 1-3, characterized in that the diamond crystals are sized and have a particle size of from 1-60 µm. Composite material according to any one of claims 1-4, characterized in that the binder consists of silicon carbide and metal silicide. Composite material according to claim 5, characterized in that the metal component of the metal silicide is selected from a group, DK 153536 B comprising cobalt, chromium, iron, hafnium, manganese, molybdenum, niobium, nickel, palladium, platinum, "rhenium, rhodium , ruthenium, tantalum, thorium, titanium, uranium, vanadium, tungsten, yttrium, zirconium and their alloys. Composite material according to any one of claims 1-4, characterized in that the binder consists of silicon carbide and metal carbide. Composite material according to claim 7, characterized in that the metal component of the metal carbide is selected from the group consisting of chromium, hafnium, titanium, zirconium, tantalum, vanadium, tungsten, molybdenum and alloys of these metals. A process for producing a composite material according to claim 1, characterized in that: a) a eutectic-high silicon-rich solid alloy or solid components producing a eutectic-high silicon-rich alloy, a diamond crystal mass and a silicon carbide or silicon nitrate substrate substrate or cup, the diamond crystal mass being placed between and in contact with the substrate and the eutectic-containing, silicon-rich solid alloy or at least one of the components producing a eutectic-containing, silicon-rich alloy, and the eutectic-containing, silicon-rich alloy consisting of silicon and a metal which with the silicon forming a silicide, b) placing the container and its contents in a pressure transmitting powder medium which transmits applied pressure? (c) applying a sufficient, substantially isostatic pressure to the container and its contents via the powder medium to substantially completely uniformize the dimensions of the container and the contents of 10! providing a form-stable, substantially isostatic system comprising the powder-enclosed container, whereby the density of the compacted diamond crystal provided provides more than 70% by volume of the volume of the compacted diamond crystals, d) the substantially ice-pressed system provided producing a liquid, eutectic. ni. <1ι; 7 r 7 / η 1 * ^ · 'i \ ι \ J Ο Ο Ο Γ) high-silicon-rich alloy that penetrates the void spaces of the compacted diamond crystal mass and contacts the contact surface of the substrate forming an interface to the compressed diamond-5 crystal mass, wherein the hot pressing is carried out at a hot pressing temperature below 1600 ° C at a hot pressing pressure sufficient to cause the liquid silicon-rich alloy to penetrate the voids in the compressed diamond crystal mass and the eutectic containing , silicon-rich solid alloy or the solid-state silicon-containing alloy components used to produce a eutectic-containing alloy are used in an amount sufficient to provide sufficient liquid, eutectic-containing, silicon-rich alloy to fill the empty spaces in the compressed space at the hot compression temperature. the contact surface of the substrate, thereby filling the pores of the interface s, so that it becomes at least substantially pore-free and wherein less than 5% by volume of the 20 diamond crystals during hot pressing is converted into free, non-diamond carbon, and this non-diamond carbon or diamond crystals react with the liquid silicon-rich alloy to form (e) cooling the provided hot-pressed substantially isostatic system and maintaining it below a sufficient pressure to at least substantially maintain the dimensions of the hot-pressed system, and f) the composite material produced wherein polycrystalline body is bonded to a silicon carbide or silicon nitride substrate, and the diamond crystals present in an amount constituting at least 70% by volume of the poly-crystal linear body are exposed. Method according to claim 9, characterized in that diamond crystals are used which are sized to 35 µl from 1 to 60 µm. Process according to claim 9 or 10, characterized in that the liquid, silicon-rich penetration alloy is used in an amount of from 25 to 80% by volume of the volume of the compressed diamond crystal mass. DK 153536 B Process according to any one of claims 9-11, characterized in that the density of the compacted mass of diamond crystals is from 71 to at most 95% by volume of the volume of the compressed crystals. Process according to any one of claims 9-12, characterized in that the silicon-rich solid alloy is in particulate form. Process according to claim 9, characterized in that in step a) a recess is used as a protective container or cup, which is pressed into the powder medium which transmits applied pressure substantially undiminished and which remains substantially uninterrupted during and in step b), the recess and its contents are covered with an additional amount of pressure transmitting powder medium, the recess being enclosed by the pressure transmitting powder medium, whereupon steps d) to f) of claim 9 are performed. Process according to claim 14, characterized in that the silicon-rich solid alloy is in particulate form. 20 25 30 35