A process for preparing a polycrystalline-diamond body

© Start of patent period: 1982 11 15 Longest possible duration:

© Issued on: 1983 06 27 © inventor:

© dependence:

AT 371 402 © Pamphlets contemplated for distinction from the prior art:

U.S. Patent No. 2,393,589, U.S. Patent No. 4,042,347

Nr.371402

The invention relates to a polycrystalline diamond body of a dense mass of

Diamond crystals bonded together by a silicon atom-containing binder. The invention further relates to processes for producing a polycrystalline diamond body of the aforementioned type.

To produce diamond bodies with high diamond content using pressures lower than the pressures in the diamond stable region of the state diagram of carbon, a suitable binder is required, which penetrates into the capillary-like cavities of a powder compact of fine diamond particles high packing density. The binder must form a thermally stable solid bond with diamond and should graphitize diamond as little as possible or not react excessively with diamond.

According to the present invention, a silicon-rich alloy containing eutectic is used, which penetrates well into the capillary-like spaces of a molding compound of diamond crystals and wets the diamond crystals to form a diamond body having excellent bonding. In the method according to the invention, pressures are used which are much lower than that

Pressures in the diamond-stable region of the state diagram of carbon. In this case, polycrystalline diamond bodies can be produced in various forms and in various dimensions, which can be used as an abrasive, cutting tool, nozzle or abrasion-resistant component.

In a method according to the invention for producing a polycrystalline diamond body, a solid mass of eutectic-containing, silicon-rich alloy or solid components for forming such an alloy and a diamond crystal mass are introduced into a cup or container serving as a shield, in that the diamond crystal mass is in contact with the solid mase of the abovementioned alloy or with at least one of the alloys intended to form the abovementioned component. The eutectic-containing, silicon-rich alloy is composed of silicon and a metal that forms a silicide with silicon. The container and its contents are placed in a pressure-transferring powder medium which transmits substantially unimpaired applied pressure and remains substantially unsintered in the required hot pressing. A substantial isostatic pressure is applied to the container and its contents via the powder medium, sufficient to substantially uniformly stabilize the dimensions of the container and contents, thereby providing a dimensionally stable, substantially isostatic system of the powder coated container. The diamond crystal mass is pressed to a packing density of more than 70% by volume. The formed substantially isostatic system is then compressed to form liquid, eutectic-containing, silicon-rich alloy and flooded therein

Subjected to a hot pressing, which is carried out at a Heißpreßtemperatur of less than 1600 ° C under a Heißpreßdruck sufficient for flooding the liquid, silicon-rich alloy into the cavities of the compressed diamond crystal mass. The eutectic-containing, silicon-rich solid alloy or provided for forming this alloy solid components are used in an amount that at the Heißpreßtemperatur sufficient to fill the cavities of the compressed diamond crystal mass sufficient amount of liquid containing eutectic rich, silicon-rich alloy. The hot pressing is carried out in an atmosphere which does not cause appreciable damage to the diamond crystals or the liquid silicon-rich alloy penetrating into the diamond crystal bulk. In hot pressing, less than 5% by volume of the diamond crystals are converted to non-diamond-shaped elemental carbon. The non-diamond carbon or diamond crystal surfaces react with the penetrating liquid silicon-rich alloy to form carbide. During the cooling following the hot pressing, the isostatic system is maintained under a pressure sufficient to substantially maintain the dimensions of the hot pressed system. After cooling, the formed polycrystalline diamond body is obtained, the diamond crystals of which are joined together by a medium rich in silicon atoms and present in an amount of at least 70% by volume, based on the total volume of the body.

In another embodiment of the method according to the invention, none is considered to be shear.371402

- 3 mung serving bowl or container used. Rather, the solid mass of eutectic-containing, silicon-rich alloy or solid components for forming such an alloy and a diamond crystal mass are introduced directly into a cavity or recess, which was previously formed with a predetermined size in a pressure-transmitting powder medium. The recess can be formed in various ways in the powder. For example, the pressure-transmitting powder medium may be placed in a die, a mold of appropriate size introduced into the powder and the powder system pressed at ambient temperature under a pressure at which the powder assumes a stable shape, so that after removal of the mold in the powder a recess which serves as a container for Aufbaum of the diamond mass and the silicon-rich alloy. After the diamond mass and silicon-rich alloy are introduced into the recess, it is covered with further pressure-transferring powder and the entire system cold pressed at ambient temperature to stabilize the recess and its contents in terms of dimensions and a substantially isostatic system for the powder-enclosed Recess with contents to create.

The invention will now be explained in more detail with reference to drawings, in which:

Fig.l a section of the state diagram of a silicon zirconium alloy with the

Equilibrium diagram for a zirconium alloy suitable for the practice of the invention, which is rich in silicon and contains a eutectic, FIG. 2 shows a section through one of containers and

Figure 3 is a schematic representation of a device for applying a light pressure to the cell according to Figure 2, wherein the cell can be vibrated to increase the packing density of the diamond crystals . 4 shows a section through a device for exerting an at least isostatic pressure on the cell according to FIG. 2 by means of a pressure-transmitting powder medium for the purpose of stabilizing the dimensions of the cell and thus forming a substantially isostatic system, FIG. 5 shows a section by a graphite mold for the simultaneous application of heat and pressure, ie for hot pressing of the substantially isostatic system with the enclosed cell and FIG. 6 a photograph (690X magnification) of a polished section of a polycrystalline prepared by the process of the invention

Diamond body.

In carrying out the method of the invention, a diamond crystal mass and a solid mass of eutectic-containing silicon-rich alloy in contact therewith are subjected to cold pressing at ambient or room temperature to substantially substantially uniformly stabilize the dimensions of the mass. Than it will be³⁵ carried out a hot pressing, wherein from the silicon alloy, a liquid, silicon-rich alloy is formed, which is washed into the mass of the compressed diamond crystals.

According to an alternative embodiment, the diamond crystal mass may be placed in contact with at least one of the components provided in situ to form the eutectic-containing 40 silicon-rich alloy, ie, silicon or alloy metal. The diamond crystal mass and the silicon-rich alloy forming components are first cold pressed at room temperature or room temperature to substantially stabilize their dimensions, and then hot pressed to form a liquid containing rich eutectic rich in silicon and introduced into the mass of the compressed diamond crystals. ⁴⁵ The silicon alloy forming components are arranged to initiate formation of the silicon alloy prior to hot pressing, ie, before the hot pressing temperature is reached.

The diamond crystal mass and the solid phase starting material of the silicon-rich alloy or the solid-phase components for forming the silicon-rich alloy may take a variety of forms. For example, each mass may have the shape 50 of a layer, wherein the two layers are arranged one above the other. The silicon-rich alloy may also be in the form of a tube or a hollow cylinder, in which case diamond crystals are packed in the interior of the hollow cylinder or tube. In a further embodiment of the invention, the silicon-rich alloy in the form of a block or

- 4 Nr.371402 of a rod in the middle of a container are arranged, in which case in the space between the block or the rod and the inner wall of the container diamond crystals are packed.

In the method according to the invention, both natural and synthetic diamond crystals can be used. The diamond crystals used have a size in the direction of their largest Ab5 measurement in the range of 1 to 1000 pm, wherein the grain size or the grain sizes depend largely on the desired packing density and also on the intended use of the resulting diamond body. When using the diamond body for grinding purposes, preference is given to diamond crystals having a particle size of not more than 60 μm. In order to optimize the packing of the diamond crystals in the diamond mass, the diamond crystals should preferably be sized or graded 10 and therefore comprise a range of grain sizes containing small, medium and large crystals. Preferably, the graded crystals are in the particle size range of 1 to 60 microns, within this range preferably 60 to 80 vol .-% of the total crystal mass lying in the upper part of the particle size range particle size, 5 to 10 vol .-% one in the middle range of Particle size range lying size and the rest have a lying in the lower part of the particle size range size.

The corresponding grain composition of the diamond crystals can be achieved by crushing larger diamond crystals in a jet mill. Preferably, the diamond crystals are chemically cleaned to remove any oxides or other impurities present on the surface before they are used in the process of the invention. For purification, the diamond crystals may be heated in hydrogen at about 900 ° C for about one hour.

The silicon-rich alloy containing eutectic as a solid phase starting material in the process of the invention consists of silicon and a metal, ie, an alloy metal that forms a silicide with silicon. The term alloy also includes an intermetallic compound. The eutectic-containing silicon-rich alloy be25 is preferably of silicon and a metal of cobalt, chromium, iron, hafnium, manganese, molybdenum, niobium, nickel, palladium, platinum, rhenium, rhodium, ruthenium, tantalum, thorium, titanium, uranium, vanadium , Tungsten, yttrium, zirconium and mixtures of the aforementioned metals group.

The silicon-rich alloy containing eutectic used as starting material is included in ³⁰ Room temperature and contains more than 50 atomic percent silicon. Usually, it contains a maximum of about 99.5 atomic percent silicon, with the silicon content largely dependent on the particular effect that the alloying metal has on the resulting silicon-rich alloy. The silicon-rich alloy used as the starting material in the solid state contains eutectic, ie a certain amount of eutectic microstructure, and can be of hypoeutectic, hypereutectic³⁵ or of eutectic composition. The example of Fig. 1 shows that the eutectic -2- is an alloy with a special composition which solidifies under equilibrium conditions on cooling at constant temperature to a solid having at least two phases and which melts completely when heated at the same constant temperature. This so-called eutectic temperature is also shown at -2-. Cut at eutectic point 2⁴⁰ the two sloping liquidus curves 3 and 4, so that the eutectic has a lower melting point than the adjacent hypoeutectic or hypereutectic compositions. The liquidus curve or liquidus line in a phase diagram represents, under equilibrium conditions, the temperatures at which, when the silicon-rich alloy is heated, it melts or begins to solidify at home. In particular, it is in the inventions⁴⁵ The eutectic silicon-rich alloy used for this purpose is an alloy of the series of alloys on a horizontal eutectic 1, ie, the horizontal through the eutectic point 2, which is an alloy whose composition is to the left of the eutectic point 2 in an equilibrium diagram and contains to a certain extent eutectic structure, that is, hypoeutectic, extends to an alloy whose combination⁵⁰ to the right of the eutectic point 2 in the equilibrium diagram and that in the certain

Measures containing eutectic structure, that is hypereutectic.

The silicon-rich alloy used as a starting material in solid form may not have the same composition as the alloy penetrating into the diamond crystal mass. If the silicon-rich alloy used as starting material in the

Hot press temperature is a total of liquid, it has the same composition as in the

Diamond crystal mass penetrating silicon rich alloy. However, if only part of the silicon-rich alloy used as starting material, ie the hypoeutectic or hypereutectic alloy in which hot pressing temperature becomes liquid, the starting alloy does not have the same composition as the liquid silicon-rich alloy penetrating into the diamond crystal mass, and in this case the penetrating silicon-rich alloy is richer in silicon than the hypoeutectic alloy used as the starting material, but less rich in silicon than the hypereutectic silicon-rich alloy used as the starting material.

As shown by the example of FIG. 1, the composition of the silicon-rich alloy penetrating according to the invention and having its melting temperature lies on the liquidus curves 3 and 4 and also includes the eutectic point 2. The area designated by 1, 2 and 4 comprises a solid phase Si and a liquid phase, namely the penetrating liquid alloy phase. As the distance along the horizon 1 increases to the right of the eutectic point 2, that is, as the silicon content of the alloy becomes greater than the silicon content of the eutectic, the proportion of the solid phase increases and the proportion of the liquid phase decreases accordingly. In the same way, the area -6- defined by 1, 2 and 3 comprises a solid phase ZrSi₂ and a liquid phase, ie, a liquid penetrating alloy phase, wherein the proportion of the solid phase increases and the proportion of liquid²⁰ decreases as the distance from the eutectic point 2 to the left increases along the horizontal 1, ie, when the silicon content of the alloy is reduced compared to the silicon content contained in the eutectic.

When carrying out the process according to the invention, the desired composition of the eutectic-containing, silicon-rich Le penetrating in the present case is found²⁵ The melting point and the melting point as a point on the liquidus curves including the eutectic point in the phase diagram of the present silicon-rich alloy and the hot-pressing temperature is the temperature at which the penetrating silicon-rich alloy of the desired composition is liquid, ie sufficiently fluid to penetrate the pressed diamond mass. When a silicon-rich alloy is used as the solid starting material, the³⁰ has the same composition as the desired penetrating alloy, the hot pressing temperature is that temperature at which the alloy is liquid and which is from 10 ° C to preferably at most 100 ° C higher than the melting point of the alloy. Depending on the alloy being used, hot pressing temperatures above this preferred maximum are also often used. However, Heißpreßtemperaturen of about 1600 ° C are unsuitable because then tend to over³⁵ moderate graphitization of diamonds.

If the starting alloy does not have the same composition as the desired penetrating alloy but is heated to the melting point of the desired penetrating alloy, such a penetrating alloy will be formed as a liquid phase. The hot pressing temperature is then the temperature at which the penetrating alloy phase is formed in liquid form, which at about 10 ° C above the melting point of the penetrating alloy phase of

Case is.

As can be seen in the example of FIG. 1, the melting point of a particular an urging alloy having a hypereutectic composition is on the liquidus line 4. For example, if the penetrating hypereutectic alloy is to contain 95 at% Si, its 45 melting point is found on the liquidus line 4 about 1400 ° C, as shown by the line 7. If the high-silica starting alloy has the same composition as the desired penetrating alloy represented by line 7, the entire starting alloy would melt at the melting point of 1400 ° C and the liquefaction or hot-pressing temperature would be from 1410 to preferably 1510 ° C or optionally reach below 1600 ° C. If⁵⁰ however, the silicon-rich starting alloy is any hypereutectic alloy that lies on the horizontal 1 to the right of line 7 in the equilibrium diagram of FIG. 1, the hot pressing temperature is the temperature at which the desired penetrating alloy is made

Atomic% Si and 5 at.% Zr, which would be the case at about 1410 ° C.

Nr.371402

At the hot pressing temperature, also from the starting alloy, the desired penetrating alloy in liquid form should be produced in an amount sufficient to fill in the voids of the compressed diamond mass whose diamond crystal density is above 70% by volume.

The liquid penetrating alloy should be produced at the hot pressing temperature practically in an amount of at least about 1 volume percent of the volume of the silicon-rich starting alloy.

The hot pressing is carried out at a temperature at which the penetrating silicon-rich alloy is liquid under a pressure which only needs to be sufficient to crack interim layers present in the diamond mass between opposing diamond surfaces to prevent the penetration of liquid alloy into the interstices of the diamond mass , This usually requires a minimum pressure of about 34 bar. In particular, the hot press pressure can range from 34 to 1370 bar, but is usually in the range of 69 to 690 bar.

Hot pressing pressures of over 1370 bar bring no noticeable advantage.

At a temperature at which the penetrating alloy is liquid, that temperature is meant at which the penetrating alloy is able to readily flow. If the alloy is at its melting point, which is given by the liquidus line and corresponds to the eutectic point in the case of a eutectic alloy, the penetrating alloy is a liquid, viscous substance. However, when its temperature is raised above its melting point, the alloy becomes less viscous and eventually becomes easily flowable at a temperature about 10 ° C above the melting point, ie, liquid. The temperature at which the penetrating silicon-rich alloy is liquid is that temperature at which the alloy penetrates into the capillary-like channels, interstices or pores of the compressed diamond crystal bulk whose crystal density is above 70% by volume. With even further increase in temperature, the fluidity of the liquid penetrating silicon-rich alloy is increased even further, so that the liquid alloy then penetrates even more rapidly into the compacted diamond crystal mass. At a temperature about 100 ° C above its melting point, the penetrating alloy usually has its highest fluidity, so that temperatures usually above this maximum temperature need not be applied,

The silicon-rich alloy with eutectic composition melts at a temperature below about 1430 ° G. For the group of silicon-rich alloys preferred here, the eutectic melting point ranges from 870 ° C. for eutectic SiPd alloy with about 56 atom% Si up to 1410 ° C. for eutectic SiMo alloy with about 97 atom% silicon. From Fig.l it can be seen that the eutectic SiZr alloy contains -2- 90.4 atom% of silicon and a melting point of

13 60 ° C has. The predominant phase of the silicon-rich eutectic alloy is almost pure silicon.

The penetrating, eutectic-containing, silicon-rich alloy has a melting point below about 1500 ° C, usually in the range of 850 to 1450 ° C, and the temperature at which it becomes liquid is at least about 10 ° C higher than its melting point.

The solid silicon-rich starting alloy or the solid components for producing the silicon-rich alloy can be used in bulk or in powder form. The amount of silicon-rich alloy used as the solid starting material in each case depends on the resulting amount of liquid penetrating silicon-rich alloy and on the capacity of the device ah. In general, the amount of penetrating silicon alloy is in the range of from 25 to 80% by volume, but preferably to achieve optimum results in the range of from 30 to 60% by volume, based on the volume of compacted diamond crystal bulk having a crystal density above 70% by volume.

The hot pressing is carried out in an atmosphere which has no appreciable detrimental effect on the properties of the diamond crystals or the penetrating silicon-rich alloy. The hot pressing can be carried out especially under vacuum or in an inert gas such as argon or helium or else under nitrogen or hydrogen. The hot pressing is carried out sufficiently fast so that no appreciable reaction takes place between the penetrating silicon-rich alloy and nitrogen or hydrogen. Hot pressing can not

- 7 No.371402 in air because diamond would graphitize rapidly at over 800 ° C and oxidize the liquid penetrating silicon-rich alloy to form solid silica before a significant amount of liquid alloy had penetrated the diamond mass.

In the arrangement shown in Fig. 2, cell -10- consists of a cup -11- (cylindrical wall of circular cross-section and bottom). Within the cup -11- is a disk -12- of eutectic-containing silicon-rich alloy, a diamond crystal mass -13- in contact with the disk -12- and a thick one. Stopper -14-, for example, a precisely in the cup -11- matching and serving as a closure cylinder arranged. Optionally, a further slice of eutectic-containing, silicon-rich alloy may be disposed between the diamond 10 -13- and the stopper -14-.

The plug -14- is made of a material which is substantially inert during hot pressing, ie causes no appreciable damage to the diamond body. Also, the plug -14- home method according to the invention with the resulting diamond body may not enter into a high-strength connection. The plug -14- may for example consist of a compact of hexagonal boron nitride or a metal such as molybdenum. The plug -14- should have sufficient mechanical strength so that the liquid penetrating silicon-rich alloy is at least substantially retained within the container.

Instead of the plug -14- can also be used a cap, not shown, which has a slightly larger diameter than the cup -11- and can be slipped over the open end of the cup to close the cup 20 --11--. The cap should fit as accurately as possible on the cup -11- so that during hot pressing, the liquid, silicon-rich alloy is at least substantially held within the cup.

The cup 11 and the associated cap are made of a material which is substantially inert during hot pressing, that is, has no appreciably damaging effect on the properties of the diamond body. Such a material may be a non-metal such as pressed hexagonal boron nitride. Preferably, however, a metal of the group comprising tungsten, yttrium, vanadium, tantalum and molybdenum is used as the material for the cup and the associated cap.

Within the container or capped cup 30, there should be no free space permitting mixing or free movement of the contents, so that the contents, at least substantially in the manner arranged, provide substantially isostatic pressure during cold pressing is subjected.

The use of diamond crystals of graded grain size is for the purpose of achieving maximum packing density of the diamond crystals. As an alternative or additional measure, the arrangement shown in FIG. 3 can also be used to increase the packing density of the diamond crystals. In the arrangement of Figure 3, the cell -10- placed on a rocking table -16- and held there during the swinging movement under a slight pressure (about 3.4 bar), so that the diamond crystals can rearrange to fill the cavities accordingly , whereby the proportion of the cavities is reduced and thus the density of the diamond mass to 40 over 70 vol .-%, based on the volume of the diamond mass, is increased. The corresponding compaction can be determined by experiments performed on diamonds of the same grain size in a die of fixed dimensions.

The filled cell -10- is then cold pressed in the manner shown in Fig. 4 at room temperature or ambient temperature. All that is needed is to apply sufficient pressure to form a dimensional45 stable, substantially isostatic system. The cell -10- is placed inside the cylindrical core of a mold -20- in such a way that it is surrounded by a mass -19- of pressure-transmitting powder medium. The powder medium consists of very fine particles having a particle size of preferably less than 160 mesh / cm (mesh size 0.037 mm), again preferred particles having a particle size of 50 2 to 20 pm. The pressure-transmitting powder medium remains substantially unsintered under the pressure and temperature conditions employed herein. As a pressure-transmitting powder medium, for example, hexagonal Bornitrit or silicon nitride is suitable. The powder medium ensures that an approximately or substantially isostatic pressure is exerted on the cell -10-, whereby the cell -10- and its contents are substantially uniformly stabilized with regard to their dimensions, ie to form a substantially isostatic system of appropriate shape containing the powder-enclosed cell in which the density of the compacted diamond crystal layer is greater than 70% by volume of the compressed crystals. The mold -20-- (ring -22- and punch --23,23a-), may be made of tool steel, optionally with the ring -22- is provided with a sintered carbide bush -22a to the application of pressures of up to 13700 bar to allow. Pressures above 13700 bar bring no noticeable advantage. Within the area enclosed by the ram -23-, the sleeve -22a- and the punch -23- space is applied to the pressure-transmitting powder medium by the ram, preferably in the range of 1370 to 6900 and usually up to 3400 bar lying pressure when the Press punches are moved in a conventional manner until the applied pressure has stabilized in the manner known in compacting powder.

The pressure used for home cold pressing can in particular be determined empirically. Increasing the pressure above the pressure value which provides a dimensionally stable, substantially isostatic system will not result in additional densification or dimensional stabilization of the cell and its contents.

A pressure-transmitting powder medium, such as hexagonal boron nitride or silicon nitride in an axial direction, exerts approximately a hydrostatic pressure effect so that a substantial isostatic pressure is applied to the entire surface of the cell, ie, the cell is pressurized from all sides with equal pressure , It is believed that the applied pressure is transmitted substantially unaltered to cell -10-. In cold pressing, the size of the voids between the crystals is reduced, so that it comes to the optimal formation of capillary-like voids or pores in the diamond mass. Furthermore, the diamond crystal mass is brought to the required packing density of over 70 vol .-%. This reduction in void volume also results in a reduction in the amount of non-diamond material ultimately present in the diamond body and results in more closely spaced crystal faces which can be effectively interconnected.

After cold pressing, the density of the compressed diamond crystals in cell -10- should be greater than 70 vol.% Of the crystal volume. The density of the compacted diamond crystal layer is in the range of 71 to less than 95% by volume, and often in the range of 75 to 90% by volume, based on the volume of the crystals. The higher the density of the compressed crystal mass, the lower the proportion of the non-diamond-shaped material reaching between the crystals, so that a correspondingly harder diamond body is produced.

The substantially isostatic system of the powder-coated container formed by cold-pressing is then hot-pressed while simultaneously subjecting the system to the hot-pressing temperature and the hot-pressing pressure.

After cold pressing, one of the two press punches -23 or 23a is withdrawn specifically and the substantially isostatic system -21- now in the form of a compact shaped body is removed from the socket -22a and transferred to the graphite mold shown in FIG. which has a hole of the same diameter as the sleeve -22a. The transferred system -21- is then trapped in hole -31- between graphite punches -32 and 32a-. To indicate the temperature of the dimensionally stabilized, essentially isostatic system -21-, a thermocouple -33- is provided in the graphite mold -30-. The graphite mold -30- with the enclosed system -21- is then placed in a conventional hot press furnace (not shown). The furnace chamber is at least substantially evacuated, which also causes an evacuation of the system -21- including the cell -10-, so that the system -21- and the cell -10- are substantially under a vacuum in which the Hot pressing can be performed. Optionally, nitrogen or hydrogen or an inert gas such as argon may also be passed into the furnace chamber to expose the furnace chamber chamber including the contents of the cell to an atmosphere suitable for hot pressing. While with the help of the graphite punches -32 and 32a an acting in the axial direction hot pressing pressure on the system -21- is exercised, takes place

- 9 no. 371402

Increasing the temperature of the system to the hot pressing temperature at which the alloy disc -12- forms a liquid, silicon-rich alloy which penetrates into the diamond mass.

When hot pressing the Heißpreßtemperatur should be achieved as quickly as possible. The hot pressing temperature is then maintained under the hot pressing pressure usually for at least 1 minute to ensure sufficient saturation of the diamond crystal mass. Usually, a hot pressing time in the range of 1 to 5 minutes is sufficient. Since the conversion of diamond into non-diamond elemental carbon depends largely on time and temperature, and in particular, the higher the temperature and the longer the temperature is maintained, the higher the probability of conversion to non-diamond elemental carbon, the hot pressing must be done before 5% by volume of diamond are converted into non-diamond-shaped elemental carbon. The extent of the conversion can be determined empirically. In the conversion of 5 or more vol.% Of diamond into non-diamond elemental carbon, a non-diamond elemental carbon phase may optionally remain in the final product which could adversely affect the mechanical properties of the final product.

The pressure applied to the liquid, high-silica alloy during hot pressing causes the formation of slag consisting largely of oxide, but also of carbide, which is usually formed between the liquid silicon-rich alloy and the diamond surfaces in the form of a refractory layer, thereby opening the capillary cavity system and then the liquid alloy can penetrate into the cavities due to capillary action. In experiments, it has been found that the penetration of the alloy into the diamond mass does not occur if a pressure is applied and maintained in the case of hot pressing on the system -21- when the alloy is in the liquid state, which is not sufficient to break up the slag.

When, during hot pressing, the liquid silicon-rich alloy penetrates and permeates the diamond mass, the liquid alloy envelops the surfaces of the compressed diamond crystals and reacts with the diamond surfaces or optionally with the resulting non-diamond elemental carbide to form at least predominantly and usually carbide carbide essentially silicon carbide. The result is a one-piece diamond body with a firm bond.

It is particularly important that substantially isostatic conditions be maintained in hot pressing, so that when the silicon-rich alloy becomes liquid, the liquid alloy can not escape between the diamond mass and the well and escape appreciably, but rather into the Diamond crystal mass -13- is forced.

Upon completion of the hot pressing, during the cooling of the hot-pressed system, at least such a pressure should be maintained that upon cooling, the isostatic pressure sufficient to substantially maintain its dimensional stability acts on the cell in the system. Preferably, the hot-pressed system -21- is allowed to cool to room temperature and then removes the diamond body formed. Optionally metal adhering to the diamond body from the container or squeezed excess silicon alloy may be removed in a conventional manner, for example by grinding.

In the method of the invention, when the silicon-rich alloy and the diamond crystal mass are applied in the form of superimposed layers, the diamond body formed has at least one flat surface and may have a variety of shapes, such as the shape of a disk, a square or rectangular bar or block. When the silicon-rich alloy in the form of a tube or a hollow cylinder, the interior of which is packed with diamond particles, is hot-pressed, the liquid silicon-rich alloy penetrates into the core composed of compacted diamond crystals, thereby forming a diamond body in the form of a circular cylinder Cross-section arises.

When the method according to the invention, the silicon-rich alloy is used in the form of a rod, which is arranged in the middle of the cup, while the remaining gap

At the end of the hot-stamping process, the liquid silicon-rich alloy penetrates the surrounding diamond crystal mass to form a diamond body in the form of a tube or a hollow cylinder.

The polycrystalline diamond body according to the invention contains diamond crystals firmly bonded together by a binder containing silicon atoms. The diamond crystals have a particle size of 1 to 1000 pm. The diamond density of the polycrystalline body ranges from at least 70 to less than 90% by volume, and often to 89% by volume, based on the volume of the body. The polycrystalline diamond body contains up to 30% by volume of silicon atom-containing binder which is at least substantially evenly distributed in the polycrystalline diamond body. The part of the binder in contact with the surfaces of the diamond crystals consists at least predominantly of silicon carbide, ie more than 50% by volume of the part of the binder in direct contact with the surfaces of the diamond crystals is silicon carbide. Preferably, the portion of the binder in contact with the surfaces of the diamond crystals consists at least substantially of silicon carbide, ie, at least about 85 and preferably 100% by volume of the portion of the binder in direct contact with the surfaces of the diamond crystals is silicon carbide. The polycrystalline diamond body is free of pores or at least substantially free of pores.

The silicon atom-containing binder always contains silicon carbide. In one embodiment, the binder is silicon carbide and metal silicide. In another embodiment, the binder is silicon carbide, metal silicide, and elemental silicon. In yet another embodiment, the binder is silicon carbide, metal silicide and metal carbide. In another embodiment, the binder is silicon carbide, metal silicide, metal carbide, and elemental silicon. In yet another embodiment, the binder is silicon carbide, metal carbide, and elemental silicon. The metal component of the metal silicide and metal carbide in the binder is the alloying metal or metals present in the penetrating alloy.

The metal component of the metal silicide present in the binder is preferably a metal of cobalt, chromium, iron, hafnium, manganese, rhenium, rhodium, ruthenium, tantalum, thorium, titanium, uranium, vanadium, tungsten, yttrium, zirconium and alloys thereof Metals comprehensive group.

The metal component of the metal carbide present in the binder is a strong carbide-forming agent which gives a stable carbide, and preferably a group comprising metal from the chromium, hafnium, titanium, zirconium, tantalum, vanadium, tungsten, molybdenum and alloys of these metals ,

The proportion of any elemental silicon and silicon carbide in the binder of the polycrystalline diamond body may vary more or less depending on the extent of the reaction between the surfaces of the diamond crystals and the penetrating silicon-rich alloy and between non-diamond elemental carbon and penetrating silicon-rich alloy. Assuming that all other factors are the same, then the amount of silicon carbide present in the binder depends mainly on the applied hot pressing temperature and the time within which the applied hot pressing temperature has been maintained. The silicon carbide content of the binder increases with increasing hot pressing temperature and / or time. It is therefore possible, for example, empirically to determine the process conditions which must be met in order to obtain a polycrystalline diamond body having a certain silicon carbide content. Specifically, the binder always contains an at least detectable amount of silicon carbide and at least one detectable amount of silicide and / or carbide of the alloying metal present in the penetrating alloy. The metal silicide is usually in the form of a disilicide, depending on the alloy used. The binder may also contain at least one detectable amount of elemental silicon. By detectable amount of silicon carbide, metal silicide, metal carbide or elemental silicon is meant the amount that can be detected by electron microscopy hei irradiation of a thin portion of the diamond body due to the electron beam diffraction occurring. In general, however, the binder contains silicon carbide in an amount of about 1 to about

Nr.371402

Vol .-%, based on the volume of the polycrystalline diamond body, and usually metal silicide in an at least detectable amount, which is often at least about 0.1 vol .-% of the polycrystalline diamond body. The amount of metal silicide present depends largely on the composition of the penetrating silicon-rich alloy. The metal silicides are hard and often have lower linear thermal expansion coefficients than the metals, or in some cases as diamond, such as rhenium, such property being desirable for a phase in a diamond body. The amount of silicon carbide and elemental silicon present depends largely on the composition of the penetrating silicon-rich alloy as well as the extent of the reaction between the penetrating silicon-rich alloy and diamond or non-diamond carbon. The amount of metal carhide present depends largely on the composition of the penetrating silicon-rich alloy.

With the help of an electron microscope can be Festge15 states when irradiating a thin section of the polycrystalline diamond body due to the electron beam diffraction occurring that the standing in contact with the surfaces of the diamond crystals part of the binder consists at least predominantly of silicon carbide.

The polycrystalline diamond body according to the invention is pore-free or at least substantially pore-free, ie, it can voids or pores in an amount of less than 1 vol .-%, based on the volume of the body included, provided that the pores or voids small (under

0.5 pm) and distributed sufficiently uniformly in the body so that they have no appreciable adverse effect on the mechanical properties of the diamond body. The void content of the polycrystalline diamond body may be determined by conventional metallographic methods, for example optically by observing a polished cross section of the body.

The polycrystalline diamond body according to the invention is also free of elemental, nichtdiamantförmigem carbon, ie it does not contain detectable by X-ray diffraction analysis of amount of elemental, nichtdiamantförmigem carbon.

A particular advantage of the invention is that polycrystalline diamond bodies of various dimensions and shapes can be produced. For example, the diamond body may have a width or length of up to 25 mm or more. Polycrystalline diamond bodies, which have a length of 25 mm or more and have a diamond content in the context of the invention, can practically not be prepared by processes in which the diamond stable region of the state diagram of carbon pressure and temperature conditions are used, since the Achievement and maintenance of such ³⁵ required high pressure and temperature conditions equipment require an extremely complex structure and therefore have only a limited capacity. On the other hand, polycrystalline diamond bodies according to the invention can be exceptionally thin down to one

Layer thickness of only one diamond crystal layer can be produced.

For grinding purposes, a part of the polycrystalline diamond body according to the invention ⁴⁰ by soldering, brazing or otherwise on a suitable support such as sintered or hot-pressed silicon carbide, sintered or hot-pressed silicon nitride or cemented carbide or of a metal such as molybdenum, to form a tool insert. The tool insert thus formed may be mounted on a suitable tool shank for use as a cutting tool in a machine tool. However, a polycrystalline diamond body 45 according to the invention can also be mechanically clamped on a tool holder and as

Cutting tool can be used.

The invention will now be explained in more detail by way of examples, which proceeded in the following manner, unless stated otherwise:

As a pressure-transmitting medium, powder of hexagonal fine boron nitride was used⁵⁰ ße, ie a particle size ranging from 2 to 20 pm used.

It was worked with a device which substantially corresponded to the device shown in Figures 4 and 5.

Cold pressing of the feed was carried out at room temperature in the manner shown in FIG

No.371402 carried out to about 5500 bar. The amount of alloy available for impregnation or impregnation of the pressed diamond mass was sufficient for complete impregnation of the pressed diamond mass.

The impregnation had a eutectic or substantially eutectic composition except for Example 6.

The polycrystalline diamond body was produced in the form of a disk.

Using a hammer and chisel, each slice was split apart substantially in half. The fractures were viewed under a microscope at about 100X magnification.

The fracture surface of the polycrystalline body was polished on a cast iron block.

A diamond density reported in each case in volume percent of the body was determined by the normalized dot counting technique, a micrograph of the polished cross-sectional area being used at 690 magnifications and the analyzed surface area having a size sufficiently representative of the microstructure of the entire body.

In the range of more than 70 but less than 90% by volume, based on the volume of the polycrystalline body, diamond density data are based on experiments carried out under similar conditions. In the diamond density data as well as the information on the appearance of both the whole polycrystalline body and the cross-sectional areas of the polycrystalline diamond body, but also the volume of the formed, purified polycrystalline diamond body compared to the volume of the diamond powder used based on the assumption that less than 5% by volume of the diamond powder has been converted to non-diamond-shaped elemental carbon.

In examples 1 to 4, 12 and 13, the high-silica impregnation was an in situ formed alloy of silicon and zirconium.

Example 1: A cast silicon wafer weighing 330 mg was placed inside a zirconium tube in a molybdenum cup. About 500 mg of fine diamond powder whose grain size was in the range of 1 to 60 μm and of which at least 40 wt% had a grain size of less than 10 μm was packed over the silicon wafer. A molybdenum cup, slightly larger in diameter than the cup loaded with silicon and diamonds, was slipped over the opening of the cup loaded with silicon and diamond as a lid.

The container thus formed was then packed in hexagonal boron nitride powder in the manner shown in Fig. 4, and the whole of the feed was pressed at room temperature, ie, cold, in a steel die to a pressure of about 5500 bar the contents of a substantially isostatic, that is, a substantially uniformly acting from all directions pressure was exercised. The pressing pressure was maintained until it had stabilized to form a dimensionally stable shaped body, ie a substantially isostatic system of the powder-enclosed container. From previous experiments it was known that the compressed diamond mass in the system as a shaped body has a diamond density of more than 75% by volume, based on the volume of the compressed diamond mass. Silicon was present in an amount of about 80% by volume based on the compressed diamond mass.

The formed container -21- of the powder-enclosed container was then hot-pressed. For this purpose, the assembly -21- was inserted into a graphite mold of the same diameter as the steel die, as shown in Fig. 5, and the graphite mold was then placed in an induction heating furnace. The induction heating furnace was evacuated to a pressure of about 13.3 mbar and then filled with nitrogen so that the interior of the container was first evacuated and then filled with a nitrogen atmosphere. The graphite mold assembly -21- was then applied and maintained at a pressure of about 34 bar. The pressurized assembly -21- was then heated inductively to a temperature of 1500 ° C in 7 minutes. During heating, the pressure increased due to the thermal expansion of the system to about 690 bar. After reaching a temperature of about 1350 ° C, the pressure dropped to about 340 bar. This pressure drop indicates that silicon-rich zirconium alloy had formed, had become liquid and had begun to press into the compressed diamond mass

No. 371402 penetrate. The pressure was increased to the maximum hot pressing pressure of 690 bar and, after reaching the temperature of 1500 ° C, the assembly was held for 1 minute at the hot pressing temperature of 1500 ° C under the pressure of 690 bar to complete impregnation of the smaller capillary-like cavities to ensure in the compressed diamond mass. The heater was then turned off, but no additional pressure was applied. In this way, a high pressure was provided at high temperature and a reduced pressure at low temperature and thus sufficient geometrical stability, ie the hot pressed assembly kept its dimensions until it had cooled to a temperature sufficient for handling.

The formed polycrystalline diamond body was removed and the adhering metal,

ie, the molybdenum cup and the remainder of the zirconium sleeve, as well as excess silicon on the outside of the body were removed by grinding and sandblasting.

The resulting one-piece polycrystalline diamond body was in the form of a disk having a thickness of about 3 mm. The diamond body seemed well soaked and had a solid bin.

By X-ray diffraction analysis of the surface through which the alloy penetrated, it was found that the body was made of diamond, silicon carbide and elemental silicon, and silicon carbide and elemental silicon were present in an amount of at least 2% by volume of the body. In the X-ray diffraction analysis, no non-diamond-shaped elemental carbon could be detected.

Examination of the disk breakage showed that the fracture surface was across the crystals rather than along the crystal faces. This indicates that the bond produced by the binder is very good and as strong as the diamond crystals themselves.

The examination of the Bruoh surfaces revealed that they were free of pores and that the binder 25 was distributed uniformly over the body.

Upon examination of the polished fracture surface, it was found that the polished surface had no holes due to broken diamond particles, indicating that there is a strong bond and the diamond body is suitable as an abrasive.

The diamond crystal density of the body was about 81% by volume based on the volume of the polycrystalline diamond body.

A micrograph of the 690X polished surface showed a white phase. X-ray spectral analysis of this phase revealed that it was zirconium and silicon, indicating that this phase was zirconium silicide.

Example 2: A cast silicon wafer weighing 170 mg was placed inside a zirconium tube in a molybdenum cup. 250 mg of diamond powder consisting of a mixture of 75% by volume of diamond particles having a particle size of less than about 62, but more than 53 μm, and 25% by volume of diamond particles having a particle size of 3, were applied to the silicon wafer about 1 to 5 pm. Instead of the one used in Example 1

Metal plate, a disk prepared by hot pressing of hexagonal boron nitride was used in the manner shown in Figure 2 as a stopper -14-.

The sealed well was then packed in powder of hexagonal boron nitride in the manner described in Example 1 and the entire feed was cold pressed under the same conditions as in Example 1. From previous experiments, it was known that in the resultant 45 the compact, the diamond crystal density of the compacted diamond mass was larger than 75% by volume. Silicon was present in an amount of about 80% by volume based on the compressed diamond mass. The cold-pressed assembly -21- with the cup enclosed by the powder was then hot-pressed in the same manner and under the same conditions as in Example 1.

The formed polycrystalline diamond body was recovered in the same manner as in Example 1. There was no binding with the plug of hexagonal boron nitride, which also had no detrimental effect on the pcly crystalline diamond body.

The monolithic polycrystalline diamond body obtained had the uniform shape of a disc having a thickness of about 1.5 mm. The disc seemed well soaked and tied. It had a more uniform shape than the polycrystalline diamond body produced according to Example 1, since the stopper -14- provided a better geometrical stability of the body than the metal cap in Example 1.

Examination of the disk breakage showed that the fracture occurred across the crystals rather than along the crystal faces. This indicates that the bond produced by the binder is very good and as strong as the diamond crystals themselves.

An examination of the fracture surfaces revealed that they were pore-free and that the binder was evenly distributed throughout the body.

Examination of the polished surfaces revealed that they had no holes due to broken diamond particles, indicating that there is a very strong bond.

The diamond crystal density of the body was 73% by volume based on the volume of the body.

The micrograph of the polished surface showed a white phase of zirconium silicide.

Example 3: The procedure was the same as in Example 2, except that the plug -14- was made of a molybdenum disk having a thickness of 3.18 mm.

The molybdenum disk had no adverse effect on the polycrystalline diamond body nor was it bonded to the polycrystalline diamond body. The molybdenum disk could be removed as well as the metal sleeve and after grinding excess silicon, a polycrystalline diamond body of uniform thickness and with a good smooth surface remained.

When examining the fracture surfaces of the disk, it was found that the fracture occurred across the crystals rather than along the crystal surfaces. This indicates that the bond produced by the binder is very good and as strong as the diamond crystals are.

The examination of the fracture surfaces showed that they were free of pores.

The diamond density of the polycrystalline diamond body was more than 70% but below 90% by volume.

Example 4: The same procedure was followed as in Example 2, except that the stopper -14- consisted of a disc of sintered alumina having a thickness of 3.18 mm.

The formed polycrystalline diamond body was not bound to the aluminum oxide disk and could be easily peeled off from the sleeve metal. After grinding off excess silicon, a diamond body with a uniform thickness and a good smooth surface remained.

Examination of the breakage of the disc revealed that the breakage was through the diamond crystals. This indicates that the binder adheres very strongly and the bond is as firm as the diamond crystals.

The examination of the fracture surfaces showed that they were free of pores.

The diamond density of the polycrystalline diamond body was over 70 but below 90% by volume.

The invention will now be explained in more detail with reference to Table I. In Examples 5 to 9, no metallic container was used, but only the same arrangement as shown in Figures 4 and 5. In carrying out Examples 5 to 9, powder consisting of hexagonal boron nitride was packed in the die shown in Fig. 4 and a cylinder serving as a press die was pressed into the powder. The cylinder was made of cemented carbide and had a diameter of about 9 mm and a thickness of about 6 mm. The axis of the cylinder was substantially aligned with the central axis of the die.

After inserting the cylinder into the powder, additional powdered hexagonal boron nitride was added to the die to completely cover the cylinder. The cylinder enclosed by the powder was hot pressed at room temperature under a pressure of 3400 bar. The punch -23a was then pulled out and with the help of the press ram -23- the molded body was partially pressed with the powder-enclosed cylinder from the die.

The exposed part of the pressed powder was removed to partially open the cylinder partially. After pulling out the cylinder, the cavity pressed in by the cylinder remained. In Examples 5-8, a cast silicon alloy disc of the stated composition was placed on the bottom of the recess. The disk had the specified density and a diameter substantially equal to the inside diameter of the recess. In Example 9, the cast alloy was crushed to a powder and the powder was placed on the bottom of the recess. A layer of diamond powder having the specified grain size was packed in the specified amount and thickness on the alloy.

A disk made by hot pressing hexagonal boron nitride powder having approximately the same diameter as the inside diameter of the recess was ground within the recess on the diamond powder as a lid to ensure that the surface of the resulting polycrystalline diamond body becomes flat.

The entire mass was then pushed with the aid of the punch -23- in the middle of the die and the punch - 23a then withdrawn. An additional amount of hexagonal boron nitride powder was added to the die to cover the hexagonal boron nitride disk 15, completely enclosing the recess and contents in the manner shown in Fig. 4 by hexagonal boron nitride. The resulting feed to the die then became hot room temperature, ie cold pressed under a pressure of 5500 bar in the manner shown in Figure 4, wherein on the recess and the contents of a substantially isostatic pressure was applied. The pressing pressure was maintained until it stabilized to form a substantially isostatic system, which is the recess and contents enclosed by the powder. From previous experiments it was known that the resulting compact, ie the substantially isostatic system of the powder-enclosed recess and contents, a compressed diamond mass having a diamond crystal density of more than 75 vol .-%.

²⁵ The formed compact with the recess enclosed by the powder and contents substantially corresponds to the arrangement -21-, but does not contain a metal container. The compact was then subjected to hot pressing, ie, pushed into the graphite mold of the same diameter as the steel die shown in Fig. 5 and placed in an induction heating furnace. The interior of the recess was evacuated and then filled with a nitrogen atmosphere,³⁰ by evacuating the heater to about 13.3 mbar and then replenishing with dry nitrogen. The graphite mold assembly was then subjected to a pressure of about 340 hours and maintained. The pressurized assembly was then heated to the indicated maximum hot pressing temperature in about 5 to 7 minutes. During heating, the pressure increased to the specified maximum due to the thermal expansion of the entire system³⁵ Hot press on.

At the indicated temperature at which impregnation began, the pressure dropped to about 340 bar. This pressure drop indicates that the indicated alloy had melted, become liquid, and began to penetrate into the diamond mass. The pressure was then increased again to the specified maximum hot press pressure and maintained at the indicated maximum hot press temperature for 1 minute to ensure complete saturation of the smaller capillary spaces of the compressed diamond mass with the alloy. The heater was then turned off, but no additional pressure was applied. As a result, at high temperature for a high pressure and a low temperature for a reduced pressure and thus provided for sufficient geometric stability. The polycrystalline diamond body formed was removed at room temperature.

The stopper did not adhere to the diamond body. After removal of hexagonal boron nitride powder adhered to the surface of the polycrystalline diamond body and excess alloy by abrasion and sandblasting, the diamond body was in the form of a disk of the specified thickness.

⁵⁰ Examples 10 to 13 were, with exceptions as indicated in Table I, carried out in substantially the same manner as Example 1.

In Table I, the hot pressing temperature at which impregnation begins is the temperature at which the alloy is liquid and penetrates into the compressed diamond mass

No.371402 starts. The indicated maximum hot pressing temperature and maximum hot pressing pressure were simultaneously maintained for 1 minute to ensure complete filling also of the smaller capillary spaces in the compacted diamond crystal bulk.

In the examples 5 to 10 given in Table I, the polycrystalline

Diamond body the shape of a disk.

The X-ray analysis with the results shown in Table I was carried out with the crushed polycrystalline diamond body.

<td colspan="2">maximum hot pressing pressure (bar)</td><td>w rt co co &lt;*&gt; O&gt; 3 »3) CT 3» CO CO CO CO CO</td>

<td colspan="2">Plug</td><td>χ χ χ xx o rt rt rt rt tn&gt; tn&gt; tn&gt; m&gt; in&gt; (1) Rt rrt. Rrt 4- »tn 3 tn 3 4-» tn 3 4J tn 3 4J tn 3 CS ω Ο. CS rt CX CS rt O. 02 V Q. CQ rt rt. fl) r-4 * 3 rt 1-1 "rt r-1 -rt rrt rrt 3 rt * rt * 3 x ra .η x re .rt x re .hl re&gt; hx ra »ri CL CX CL CX Q. CX Q. CX Q. CX rt O 44 rt O 44 rt O 44 rt O 4- rt Q -4-³cn cn · η cn cn .rt cn σιη σ »σι · κ cn cn · η cq re β cq re e cq rt s eQrtc cfirec ♦ rt XX .rt XX .rt XX »rt XX · Η XX ο oο r rt ο »ω o» o&gt; rt rt o £ j; ffl aS «SCD -C CD -C JC CQ -C JQ £ Q</td>

<td colspan="2">Hetallbehälter</td><td>χ χ χ χ 2 α rt ο ο .5 = cc C It does not matter 2 rt rt rt -X -X</td>

<td rowspan="3">t. ω&gt; rrt 3 O_ 4-&gt; C rt ε rt ♦ rt O</td><td>B B O ever Ü ♦ rt α</td><td>-4 · «4 · -4 *« 4- rrt rrt ^ 4 ^ 4 ^ 4</td>

<td>(Rag)</td><td>&lt;1-0 0 0 0 to to m to CM CM CM CM C4</td>

<td>ε Third O cs :O X ts</td><td>X 1 o cc] li 1 • rt »rt -rl -rt .rt .rt ε rt rt e ω ε α&gt; ε e Hear 3 rrt 3. r4 3. · -ι 3. ε -XEJ £ £ -XB -X ε -X _ 3. 3. tn o 3. tn o 3. tn o a. ω _ O &amp;? C &amp; imrt C &amp; rrt Ci '?' - = O 13. O rt | O rt 1 place) O rt 1 to tn · co 4y · tn &lt;o44 * u) to 4³ · Tn to 4 ^ · tn eso tn s -ims &lt;-i tn srt to s -t in β) ω ♦ -ι (Oflirtre ω ω ω re in ω ω re in ω rt re • rl 4-&gt; ts · ι-Ι Ό ts rtrt Ό &lt;«« t t t t t t t t CD CD CD CD .a tn tn .acx yes ex yes ex _o cx ß) O rrt .rt ert rt .rt O rt .rt O rt .rtOrt rt -σ -4- re r4 E &lt;J- C «-4 E« 4- C -4 £ «4- C WE-iC</td>

<td>alloy</td><td>£ ε rt ever • rt Q</td><td>to -C rt O 4-) re xe - · * rt - »l 4-&gt; , _ _ XX XX ♦ · · r r r r r X X X X X X X X X rt ne r-1&gt; .rt X rrt CQ rt O 3 3 -rt &gt; Q_ ts je</td>

<td>ever c sre x</td><td>3) £</td><td>«4-0 0 0 0 to to O rrt O CM CM CM CM CM</td>

<td></td><td>7 B O</td><td>• rt. Rt. Rrt. Rrt .rt. Rt t / 3 OS MC tn H- tn r- MX tf) ΙΛ oo in in to to co O »r4 ΟΪ CO 1-4 CO rrt r * CM</td>

<td></td><td>example</td><td>in to r ** co o</td>

Nr.371402

Table 1 (continued)

<td colspan="2">! CD "H V TO 3 &lt;·&gt; 'yours R} -Ι cd yes ra ra E i- • H CL X (0 e</td><td>^{10 10} SS in m ss rs Γ · co co</td>

<td colspan="2">C 05 CU O. O JJ t / i</td><td>1 ll YY in Ό YYMT3 YY 10 Ό (_ 3 CU □ C ^u 2. Ξ ra ra i 3 ra ι 3 c ra ra _ 3 tbb; ra -cε t. ι-ι ra ό jj c ι-ι ra 3 jj t&gt; u γη ra ό jj 03 IJ C_ · Η rl o 1-1 U «H rH ja« rH U · Η rH 4J ra &lt;u Ja ra jj ra M- ja ra&gt; · · £ «cu -q ra CJ - »- iu_o c jj h c_ .a -ι cjJ · -tu-Q • h ra o ro ©. Η ra o ra ο o. H ra o ra o (Λ E 3S o oo ε »U = COESOb ^</td>

<td colspan="2">e re + J · -ι: ra • E υ • O ra u ω</td><td>CT cn 05 05 C c C c 3 3 3 3 jj -o jj-α jj ό JJ β • Il-1. * · Ι-Ι «H · Η * d * 7 * E 03 a 05 605 E re I-1 ι-1 r-I · -1 q_ -X CU -X iU JC M- -X o. in q. in cl in g. " re 3 re 3 «J -2J5 z «xz £ k &lt;as« c¹¹ 'i' '' X IN IN £ NJ</td>

<td></td><td>ε B ra o • H Q</td><td>sas</td>

<td></td><td>05 e</td><td>in * £ o oj in o co pj pj ro</td>

<td>diamond powder</td><td>e Third &lt;u cs :O c. to</td><td>.1 .1 years *, 05 E 03 E 03 EC \ J ZL 1-13. l | third rH 3. &lt;3 Ε -X Ε -XE -X 3. Ui O 3. u&gt; O 3. «0 O. v&gt; c δ-? · - · c fr? · -1 c ctS * - »ft? h J8 « Oral oral O 0&gt; 1 J -QJ Ή io jj · in to jj · in to jj · w · · - © in 3 ι-1 ut 3 rl &lt;&lt; 5 3 · -1 3 CO 3 u&gt; ra ra ra ω ra ra ra «rarer re in re h • Η T3 CD .rl 'O CD .h -o CD &lt;5 to _o ce _o c £ _ new JJ JJ «Η O 03« Η O 0) · Η O 03 Ο · Η O · «- * τΗ EC ^ JEJtC «-IE &lt;· C f ^ ECOE</td>

<td rowspan="2">ct c 3 c_ 0) CT 03 C C 1-</td><td>Thickness (mm)</td><td>in r * Il W o</td>

<td>cn e</td><td>o ro PJ co ο cn iS ro fj</td>

<td></td><td>$$ l ε O JJ "X</td><td>i 1 l · Η 1 «rl • HO .HC 03 rH v - &lt; ° ^{w 22} Sw Sw "T" T. CT in 3 CT W 3 rs. C / J CO PJ 03 ra iH 03 .rl r »pj coro ct cn ctcn</td>

<td></td><td>example</td><td>O w pj 2</td>

Nr.371402

Table I (continued)

<td colspan="2">X-ray analysis</td><td>ct c s CT • rt • rt »rt = e / 5 tn »h ao CC * Ο ίο ONC .rt β N ~ &gt;&gt; «Rt Ο 1- &lt;3 · Η 7 cn&gt; e t. tn c / o₌ c .rt .rt 0) .rt ω 0) 0) 1- C fl)&gt; 1- tu 1 s_s- o - = OQ. oo. oswo'o o .rt W .rt ω .rt Q. t_&gt; · Η »rt t # tn tn co tn tn ~ α Ό CU Ό "C * C" .CSC * 4J 3 44 3 4J O 3 44 44 - SC 3 * £ - CC «Ra ~ cu cu n ts cu tu B † rrt B † r † r ra tn cu tn cu tn u-cu ra «Η O» rt 0) «rrt .rt 0) σ» rl »rt O _e Q fi * Q tn OS ra QQ</td>

<td rowspan="2">Polycrystalline diamond body</td><td>characteristics</td><td>4-&gt; u cu _Q V. ( cc · - * aj SCU Γ * »cu T3 4- »44 cwf-i ω a i-o o i: yes ci »rt 44 Α _A α β&gt; o Q. t-tn ω _ = cu -Q σι Ό&gt; w »cu« tas -css · = s .h § § · 3 £ t I r s = £ ⁿ .5 u £ §&gt; 'S »", § ü 2 fe c ω cw ο ω ω tu σι 2 5 _h 5, «* d «©« βίββί w μ. 4J ό »E^{, rl} t in 5 Ϊ - »r- ..J -J r-» ffl β C 44 4- * 4- »- tn i-1» rt © 'w 2 c * qw «cc» i- ω = ra j = 3 «« ± 1 V t a © ra o aocuo 3 »ο σι · £ £. 5 'd tt a s_ t- a eraae.rt cs ³ 'd 2 * 5 -ö LU 44 O * 3 LU 44 O fl) CQ.rtO O fl) a Β «Λ Q- e tn ai c &lt;n rm 4J * io «) 5 * ±? 3 0) .rt 3 fl) »CT B C. 44 3 CT C 44 44 L · c (fl 0) c en 03 .rt 3. ts 4) w,. »D 2 3,⁰¹ , , _j qj aj 4J_lp| qj 44 0) a fl) 44 fl) CT CU ^ 3 u SC £ L 5 = a NO ► U CS -X NC 44 c W ra .Η »η raze» h r rt ou »nc« ra L. e fl) c_ t ". - oi rt .q * - * ei .qet- * ra c · »: ra ct ra © -q ra a 'ω _ □ A w .uu T- a&gt; 4J Q. fl) CL »44 CT CU» 44 CT ra JS CU · -1 C 44 -C · t_, 5s α- H. _i ._4 rt Ο OS 3 0) C&gt; C O IO C U&gt;, O 'qJose cu β) 3 e: c0 44Q.t_ira o occurred. -χ · &lt;-ι ja ts * s »e. 3 i-l 0J 44 rat. C- · - · 3 44 C 44 ΐ.? . &amp; 'S ΐ.? .κ HS 0 Sⁱ £ § s § α = £ -S? 3 £ 15 S - §§§§. £ -P SS. §-§§ · § 0 0) »rt» rt 0 fl) »rt U C.» rt 3 3 L -H .rt 0J 44 «rt Q. M-U4 V3 Q. 4- LiJ t / 3 cOtDQCMTO CT CD "OQ ·"? (Λ O</td>

<td>thickness (Mm)</td><td>c1 C4 C4 C4 CO Ss 1Λ in in r «</td>

<td>melting point</td><td>the impregnation (° c)</td><td>'S. 'S. " ra cu S θ 'S 0 SS £ - ° cm ct in CO 2 S2 ίΰ λ »Rttfl CM tn t *&gt; COCM CM 0 ^ .3 ^w2 .-. ra - 'ra C. £ _7 ss £</td>

<td>O O 3 44 CU</td><td>maximum</td><td>in in 0 θ ^ 5 2 " ⁵ 5 pounds 2 pounds</td>

<td>03 Q_ ε α cs ίΟ. it is qj se</td><td>begin the impregnation</td><td>tC S 2 i? 2 o £ S cn 2 w 2</td>

<td></td><td>example</td><td>m 10 r * co ct 0</td>

Nr.371402

Table I (continued)

<td colspan="2">X-ray radiation analysis</td><td>1 ί!</td>

<td rowspan="2">0) Q. C_ SO -X * » c ra ε ra • rt Q s. &lt;u c "rt ra VI • rt C. &gt; s rrt O O_</td><td>characteristics</td><td>Diamond body well soaked, did not adhere to Sinterhartnietallstopfen, however, was in contact with Sintered carbide plug diamond surface considerably damaged (graphitized) Diamond body was made by sandblasting with Silicon carbide particles were purified and showed a excellent erosion resistance against the very abrasive jet · Also, the surface in contact with the molybdenum plug showed no damage In contact with the cemented carbide plug standing diamond surface was very strong graphitized, but the rest of the body, ie about 2/3 of the body, were through the stopper not damaged. Polished section showed over 70 vol .-% diamond and impregnation of the fine Cracks in the used large diamond crystals</td>

<td>thickness (Mm)</td><td>5 ^{1 1}</td>

<td>melting point</td><td>the drink Alloy (° C)</td><td>= - - t - - • 2 rM -e tM -c C tj o in .oo _O ._H O &lt;r » «D-iS * 4J to ► -P C Σ 'Ol CO oil · - ♦ s; · - · φ - * ο 4rt .rt 4J - CO 3 CO 3 • rt _ · Ο tt&gt; CO</td>

<td>O t_ 3 +&gt; ra</td><td>maximum</td><td>tn o r- © tri co tn tn</td>

<td>c- (U Q. e V cc O u O. cc ω zc</td><td>begin the impregnation</td><td>ooo in m ι co tn »- · -¹</td>

<td></td><td>example</td><td>CM CO rt »rt</td>

Nr.371402

The polycrystalline diamond bodies produced according to Examples 5 and 6 were well saturated and well bonded. Examination of their fracture surfaces revealed that they were pore-free, the binder was evenly distributed throughout the body, and the fracture was through the crystals. The diamond density of each body was higher than 70 but below 90% by volume.

In the diamond body produced according to Example 7, the fracture surfaces showed pockets of fine diamond powder up to 100 μm in size, which was imperfectly saturated, probably due to inhomogeneous mixing of the diamond crystals. The

However, the remainder of the body was completely saturated and had a diamond density of over 70 but below 90% by volume.

Example 8 was conducted in the same manner as Example 7, but using higher hot press temperatures, thereby achieving complete saturation of the compressed diamond mass and forming a hard disk with good bonding. Upon examination of the fracture surfaces, they were found to be pore-free, the binder was evenly distributed throughout the body, and the fracture was across the crystals. Upon examination of the polished surface of the diamond body prepared in Example 8, no holes attributable to broken-out diamond particles could be found, indicating a strong bond. The polished cut surface is shown in Fig.6. The diamond density of the body was 80% by volume.

In the diamond body produced according to Example 9, although the fracture surfaces showed the same incomplete impregnation as in the diamond body prepared according to Example 7, but the rest of the body was well soaked through and well bonded.

It can be seen from Examples 10, 11 and 13 that a cemented tungsten carbide and cobalt cemented carbide plug is unsuitable for the process. In the diamond bodies prepared according to Examples 10, 11 and 12, testing of fracture surfaces not affected by the plug revealed that they were nonporous, cracked across the crystal particles, the binder was uniformly distributed in the body, and each diamond body had a diamond density above 70 vol .-% had.

In the diamond body produced according to Example 12, the fracture surface examination revealed that they were nonporous, cracked transversely through the crystal particles, and the binder was evenly distributed over the diamond body having a diamond density greater than 70 but not greater than 90% by volume. had.

When examining the fracture surfaces of the diamond body produced according to Example 13, it was found that the alloy had penetrated into fine crystal cracks, which may arise during hot pressing in larger crystals, resulting in an extremely good integration of these crystals.

Reference is made to US Pat. No. 3,982,911, which discloses a method of making a

Cubic boron nitride abrasive body is explained, wherein cubic boron nitride crystals are brought together with a substrate and an alloy serving as a binder in a metal container to be shielded, the container is placed in a pressure-transmitting powder medium, on the container and its contents on the powder medium in the isostatic pressure is applied and the container enclosed by the powder is subjected to a hot pressing.