SE415882B - HARD METAL COMPOSITION BODY, IN PARTICULAR FOR GRINDING OR CUTTING TOOLS, INCLUDING CRYSTIC BORNITRID CRYSTALS AND HARD METAL MATERIALS AND PROCEDURE FOR MAKING THE COMPOSITE BODY - Google Patents

Description

7208677-0 2 of the compact. A special property of these alloys when used as a binder is obtained in the production of compacts of cubic boron nitride with a crystal size of, for example, less than 30 .mu.m.

If crystals of cubic boron nitride with a size exceeding 80 rooms as the largest dimension are acceptable, high-pressure processes can be carried out according to the invention, in which case the aluminum alloys mentioned above do not need to be used as binders.

Combinations of crystals of cubic boron nitride, carbide powder and diamond crystals have also been used with good results for the production of useful compacts. Composite bodies in which a layer of crystals of cubic boron nitride has been bonded to the surface of a cemented carbide sheet have also been produced, the layer of cubic boron nitride being found to be substantially free of cavities. The invention is further elucidated in the following with reference to the accompanying drawing.

Figure 1 shows an example of a device intended for high pressure and high temperature which is suitable for carrying out the invention.

Figure 2 shows a section through a form of a charging unit intended for use in the device according to Figure 1 in carrying out the invention.

Figure 3 is a three-dimensional view showing a composite cutting insert of cubic boron nitride for machining. Figure 4 is a section through the cutting plate according to Figure 3 along the line XX or the line YY.

Figures 5 and 6 are three-dimensional views of cubic boron nitride / cemented carbide composite cutting plates made according to the invention.

Figure 7 is a section showing a combination of liner and loading unit for making articles according to Figures 3, 5 and 6.

Figure 8 shows a section through another embodiment of a charging unit for use in the device according to Figure 1 in carrying out the method according to the invention.

Figure 9 is another three-dimensional view showing a composite cutting plate containing cubic boron nitride.

Figure 10 is another section along the line XX or YY through the cutting plate of Figure 9.

Figure 11 is a section showing a combination of liner and loading unit for making the articles of Figures 9, 5 and 6.

A preferred embodiment of a high pressure and high temperature device in which composite cutting plates of the invention can be made is described in U.S. Pat. No. 2,941,248,720,8677-'0 3 (which is intended to be part of the present specification) and is shown in Figure 1. Reaction vessel designs useful in the practice of the invention are described in U.S. Pat. No. Afs. p. 144, January 2, 1970), which is incorporated herein by reference.

The device 10 comprises a pair of carbide pressure stamps 11 and 11 'and an intermediate belt or matrix part 12 of the same kind of material. The matrix part 12 is provided with an opening 13, in which a reaction vessel 14 is arranged. Between the pressure stamp 11 and the matrix 12 and between the pressure stamp 11 'and the matrix 12 there is a gasket insulation unit 15, 15', which in each case comprises a pair of heat insulating and electrically insulating pryophyllite parts 16 and 17 and an intermediate metal gasket 18.

According to a preferred embodiment, the reaction vessel 14 contains a hollow salt cylinder 19. The cylinder 19 may be made of another material, for example talc, which a) is not converted under the influence of high pressure and high temperature in the process to a stronger, stiffer state (e.g. by phase transformations and / or compression), and b) is substantially free of volume discontinuities under the influence of high temperature and high pressure of, for example, the kind found in pyrophyllite and porous alumina. Materials which meet the requirements of U.S. Pat. No. 3,030,662 (column 1, line 59 - column 2, line 2, which is intended to form part of the present specification) are useful for the manufacture of cylinder 19.

Conoentrically in and next to the cylinder 19 a graphite electric resistance heating tube 29 is arranged. In the graphite heating tube 20 there is in turn concentrically arranged the non-cylindrical salt liner 21. The ends of the liner 21 are provided with salt plugs 22, 22 ', arranged at the upper and lower ends, respectively. As described below, the liner 21 may have a cylindrical hollow core for receiving a large loading unit containing suction units, or the liner may consist of a series of mold units arranged in a stack for the manufacture of a plurality of composite plants. fabric inserts, for example as shown in Figures 5, 5 and 6.

Electrically conductive metal end plates 25 and 25 'are used at each end of the cylinder 19 to provide electrical connection to the graphite heating tube 20. Adjacent each plate 25, 23' is an end cap assembly 24 and 24 ', each of which includes a pyrophyllite plug or disc 25, which is surrounded by an electrically conductive ring 2 (.

Working methods for the simultaneous effect of both high pressure and high temperature in this device are well known to those skilled in the art. The foregoing description relates only to one type of high pressure and high temperature device. Various other types of devices can be used to provide the required pressure and temperature according to the invention. Figure 2 shows an arrangement for producing a plurality of sheet or tablet-shaped composite bodies (cemented carbide substrate with a layer of sintered cubic boron nitride formed on the substrate) using aluminum alloy as a binder. The charge unit 30 (which is not shown on the same scale) fits into the space 31 in the device of Figure 1. The charge unit 30 consists of a cylindrical sleeve 32 of casing metal, which may be zirconium, titanium, tantalum, tungsten or molybdenum. Arranged in the cylindrical sleeve 32 of casing metal are arranged a number of subunits which are separated by plugs 33 of the same kind of material as the cylinder 19, for example hexagonal boron nitride or NaCl, which remains substantially unchanged during the execution of the process and facilitates the separation of the subunits after the process. Each subunit is enclosed in a cup-shaped portion 34 with end cap plates 34a made of some of the materials that can be used for the sleeve 32, preferably zirconium or titanium. In each subunit, a mass 36 of finely divided (less than about 30, mm) crystals of cubic boron nitride is arranged between a mass 37 and a pair of metal plates, a plate 38 of aluminum and a plate 39 of alloy metal, which may be nickel, cobalt, manganese, iron, vanadium and chromium. The mutual positions of the plates 38 and 39 are not of critical importance provided that the formation of aluminum alloy takes place. The mass 37 may be cemented carbide (sintered carbide) or sinterable carbide powder, the sintering taking place during the consolidation of the cubic boron nitride. The amount of aluminum used in relation to the amount of alloy metal is not critical and can vary from approx. equal parts by weight to approx. 1 part aluminum per 10 parts alloy metal.

In the production of cutting plates with this embodiment, the charge unit 3041 arranges the device 10, pressure is applied and the system is subsequently heated. The temperature used is in the range of approx. 1300-160000 for a period exceeding approx. 3 minutes, at the same time exposing the system to very high pressure, for example of the order of 55 kilobars, to ensure that conditions are maintained under which the cubic boron nitride in the system is thermodynamically stable. At 1300 ° C the minimum pressure should be approx. 40 kilobars and at l600 ° C the minimum pressure should be approx. 50 kilobars. At the temperatures used, sintering agent was melted in the mass 37, so that cobalt, nickel or iron (depending on the particular carbide composition) is made available for migration from the mass 37 into the mass 56, in which the metal is alloyed. with the molten aluminum alloy formed by the plates 38 and 39 and by reaction in the cubic boron nitride. The metal material thus formed acts as an effective binder for the crystals of cubic boron nitride near the interface between the masses 37 and 56 for bonding these crystals to each other and to the cemented carbide. The rest of the crystals in the mass of cubic boron nitride are bonded together by the metal material formed by alloying the discs 58 and 39 and by reacting this alloy with the cubic boron nitride. _ The amount of aluminum in the starting material can vary from approx. l to approx. 40% by weight of the amount of cubic boron nitride and the amount of alloying metal (nickel, cobalt, manganese, iron, vanadium and chromium) can vary from approx. 2 to approx. 100% by weight of the amount of cubic boron nitride. The amount of these alloying metals remaining in the consolidated cubic boron nitride as matrix material varies depending on the pressure and the period of time during which high pressure and high temperature are caused to act. In many cases, the amount of aluminum plus alloy metal atoms in the compressed cubic boron nitride is more than about 1% by weight of the amount of cubic boron nitride.

Preformed aluminum alloys can of course be used instead of separate sheets for in situ alloying.

After completion of the process carried out at high temperature and high pressure, the temperature is lowered first and then the pressure.

After recovering the masses useful as cutting plates, the protective casing metal is strongly bonded to their outer surfaces.

Exposure of the desired surfaces to the composite cutting plates is most easily accomplished by grinding away the protective casing metal.

Using aluminum lining as a binder as described above, a variety of cubic boron nitride and cemented carbide composite bodies have been successfully prepared using cubic boron nitride crystals having a size of 110 .mu.m.

These compacts have significantly superior abrasion properties compared to cemented carbide bodies. Cubic boron nitride compacts (which are not bonded to cemented carbide substrates) have also been made from cubic boron nitride crystals within this size range using subunits in which no mass 57 is used.

In many of the examples given below, which pertain to this embodiment, a slight excess of aluminum alloy is formed, which remains after the infiltration between the crystals of cubic borvvoesovfo 6 nitride is completed. This small excess can be alloyed with the beaker 34 or with a portion of the cemented carbide mass 36.

After lowering the temperature and pressure, the composite bodies are removed and can then be ground to a shape for use in cutting tools.

When examining a polished surface of such a body under a microscope, one can observe a plurality of fine cubic boron nitride particles which are tightly connected to each other with the small gaps between the crystals filled with a second phase which appears to be metallic. Thus, scratches on the polished surface were observed in contrast to strands of holes from fragments of cubic boron nitride picked out, as had been observed on polished surfaces of compacts made using other active metals as binders. Penetration between and bonding of the crystals of cubic boron nitride through the binder is very good in composite bodies and compacts of cubic boron nitride prepared according to the invention. Characteristic X-ray diffraction diagrams are obtained for each special alloy system (aluminum plus any of the specified alloy metals). These diffraction diagrams have shown the presence of cubic boron nitride, AlN and additional unidentifiable phases. Electron beam microprobe testing of composite bodies and cubic boron nitride compacts made with aluminum and nickel as the source of the binder shows that both Al and Ni are present in the gaps.

The comminuted crystals of cubic boron nitride are preferably produced by jet milling of larger grains of cubic boron nitride. Prior to their introduction into the reaction vessel, the fine crystals of cubic boron nitride (900 ° C, 1 hour) in ammonia are suitably heated to further clean the surface of the crystals.

Some composite bodies of cubic boron nitride and cemented carbide made according to the invention have been formed into tools (square surface, approx. 6.1 mm edge length) and used for cutting "lnconel 718", which is a nickel-based heat-resistant alloy. A typical Ni-Al bonded vent fabric would have had a surface layer of bonded cubic boron nitride with a thickness ranging from 0.76 to 0.25 mm strongly bonded to a cemented carbide backing block (e.g. grade 883 carboloy cemented carbide) having a thickness of approx. 3.05 mm. The wear of such tools was generally significantly less than the wear obtained when using "grade 883 Carboloy" tools under the same conditions.

A number of composite bodies made according to this embodiment were subjected to abrasion testing, with a rod having a thickness of 3.5 mm of "René 4I" (a nickel-based heat-resistant alloy) rotating at a speed of 200 rpm. , was pressed against the layer of cubic boron nitride on the tested composite body with a force of 56 kp for 5 minutes. The depth of the abrasion groove on the compact was then measured. In each of the examples given below, the arrangement used was essentially the same as for a subunit shown in Figure 2. The protective beaker (or sleeve) used in each case had a diameter of 6.4 mm, unless otherwise indicated in the examples, the whole amount of cubic boron nitride was jet ground (largest grain dimension 1-10 Ålm) The cubic boron nitride used in Examples 2 and 6 had been heat treated in NH before loading, in each example a pre-sintered cemented carbide plate ("8S5 grade Carboloy" cemented carbide) was used as the backing block in the press body. pen.) Example 1.

A beaker of zirconium was filled with a pre-sintered cemented carbide disc (thickness 1.27 mm), came from clinical bernltrld (0.060 g), Al-disc (0.010 g) and Co-disc (0.034 m). The device is simultaneously subjected to the influence of a pressure of 54 kb and a temperature of 155000 for a period of 61 minutes. The bonding of the cubic boron nitride to the cemented carbide and the bonding of the grains of cubic boron nitride to the metal matrix were good. The consolidated portion of cubic boron nitride could be polished well.

Abrasion testing gave a groove depth of 0.054 mm. Example 2.

A Mo-sleeve (thickness 0.051 mm) with Mo-end plates (thickness 0.051 mm) was loaded with a forged kerbic plate (njcekiek 1.27 mm), grains of cubic boron nitride (0.065 g), Al-plate (0.010 g) and a layer of a mixture of powders of Co (0,055 g) and Al (0,004 g). The unit was simultaneously subjected to a pressure of 56 kb and a temperature of 1500 ° C for 65 minutes. Good bonding of the cubic boron nitride to the cemented carbide and to the metal matrix was obtained.

The cubic boron nitride in the metal matrix exhibited a densely packed microstructure. Abrasion testing gave an abrasion groove depth of 0.025 mm.

A beaker of Zr was charged with a sintered cemented carbide plug (thickness 1.27 mm), grains of cubic boron nitride (0.060 g) and a mixture of coarse powder of Al (0.010 g) and Mn (0.04 g). The unit was simultaneously subjected to a pressure of 55 kb and a temperature of 155,000 for 60 minutes. The bonding of the cubic boron nitride to the cemented carbide and to the metal matrix was good. The compact part of cubic boron nitride in the composite body could be polished well. Abrasion testing gave an abrasion groove depth of 0.012? mm. . 7208677-o Example 4.

A Mo beaker was loaded with a sintered hard metal plug (thickness 1.27 mm), fine-grained cubic boron nitride (0.060 g), an Al wafer (0.005 g) and a mixture of powder of V (0.010 g) and Al (0 .010 g).

The observed properties of the composite body and the compact body part of cubic boron nitride were similar to the nos product according to the examples observed.

The abrasion groove depth was 0.039 mm.

Example 5.

A Zr beaker (thickness 0.051 mm) was loaded with a cemented carbide disc (thickness 5.08 mm), a disc of 90 Fe 10 A1 (thickness 0.20 mm x diameter 6.25 mm, weight 0.025 g) and grains of cubic boron nitride (grain size 0.149 / 0.125 mm, 0.093 g). The metal alloy sheet was arranged at the surface of the cemented carbide in contact with both the cemented carbide and the cubic boron nitride. This unit was simultaneously subjected to 55 kb of pressure and a temperature of 1500 ° C for 60 minutes. The composite body prepared in this way was examined, and it was found that considerable direct bonding between grains of cubic boron nitride and between grains of cubic boron nitride and cemented carbide had been obtained.

Example 6.

A Mo beaker was loaded with a cemented carbide disc (thickness 1.27 mm), cubic boron nitride (0.080 g, l-20 / μm), an Al disc (0.055 g) and a span of "Inconel 718" (0.0 } 5 g). Inconel 718 has the following composition in weight-p: 52.5% Ni 0.6% Al 0.2 91% Mu 19 96 cr '18 96 Fe 3 76 Mo 5.2 9% Now 0.8 'get free The unit was simultaneously subjected to a pressure of SH kb and a temperature of 150,000 for 60 minutes. Good bonding had been obtained between the cubic boron nitride and the cemented carbide. The mass of cubic boron nitride was very dense and contained very little amount of matrix. This metal matrix was very well bound to the grains of cubic boron nitride.

Abrasion testing gave an abrasion groove depth of 0.018 mm.

Example 7.

A Zr beaker was loaded with a sintered disk (thickness 1.27 mm) and a mixture (0.065 g) of cubic boron nitride grains plus "grade 55A Carboloy" (low% Co, 8?% WC) carbide powder (0.052 g) and Al powder (0.003 g). The unit was simultaneously subjected to 55 kb of pressure and a temperature of 1500 ° C for 50 minutes. A certain degree of sintering of the cubes of cubic boron nitride was obtained and good bonding was observed between the grains of cubic boron nitride as well as both the sintered ski and the metal matrix. Abrasion testing gave an abrasion groove depth of 0.0089 mm.

Example 8.

A Zr beaker was loaded with a sintered carbide disc (thickness 0.27 mm), a layer of "grade 190 Carboloy" carbide powder (0.046 g, 76 co, 75% wc), a swap disc (o, o1o g) and kor-n of comm: bonn- trid (0.06O g). The layer of carbide powder was applied over the surface of the sintered sheet and the Al sheet was applied between the carbide powder layer and the cubic boron nitride. This unit was simultaneously subjected to a pressure of 57 kb and a temperature of 155,000 for 60 minutes. Good bonding was obtained between the sintered carbide and the in situ sintered carbide. Good bonding was also observed between the cubic boron nitride and the metal matrix. A few larger (20-30 m) metal islands were observed. The portion of consolidated cubic boron nitride was well polished. Abrasion testing gave an abrasion groove depth of 0.0ll5 mm.

Example 9.

Two composite bodies were produced for forming into turning tools. In each case, the arrangement shown for a subunit of Figure 2 was used. A 8.9 mm diameter Zr cup 34 and a lid 34a were used. A cemented carbide disc (883 grade Carboloy) with a thickness of 2.95 mm was used as pulp 37 and 0.120 g of purified jet ground cubic boron nitride (1-10 m) was used as pulp 36. An Al disk 38 with a weight of 0.020 g and a Ni disc 39 weighing 0.066 g was used. This unit was simultaneously subjected to a pressure of 55 kb and a temperature of 150,000 for 60 minutes.

The composite bodies were recovered, formed into finished dimensions (thickness 3.15 mm X 6.1 mm square edge dimensions) and tested.

For Comparison with a grade 883 Carboloy tool, the two lathe cutting tools of Example 9 were used for cutting "Inconel 718". Under conditions which gave approx. 0.3 mm abrasion on a grade 883 Carboloy tool, the cubic boron nitride composite body had an abrasion of only 0.1 mm on the surface of the compression body which had abutment against the workpiece. The chip-breaking surface (of cubic boron nitride) of the composite body was not severely worn with the exception of a groove against which the outer corner of the chip abutted. The same type of abrasion occurred on all tested tools (including the Carboloy tools). The occurrence of this special type of abrasion on all tools was predictable, since all tools had been manufactured with the same geometric shape. The composite bodies of cubic boron nitride gave better results than the tools of "Carboloy", when the cutting speed was increased.

The preferred direct bond is the bond obtained in situ between the cubic boron nitride material, which has a very high strength, and the substantially larger mass of underlying cemented carbide substrate material. This direct bonding eliminates the need for an intermediate adhesive layer between the press body and the substrate, for example as would be obtained with brazing or soldering. By arranging a rigid, non-resilient substrate material in direct contact with the cubic boron nitride - rich cutting edge portion, the tendency to crack in the cubic boron nitride material is greatly reduced, and a smaller amount of cubic boron nitride is required to make a tool.

The composite cutting plates shown in Figures 5, 5 and 6 were made in a non-cylindrical shape, joining a cemented carbide substrate and fine-grained cubic boron nitride in the presence of a special material combination, a modified design of the salt liner 21 and the plugs 22, 22 '. required. The construction fitted in the heating tube 20 can be embodied as a series of cylindrical blocks, which are stacked on top of each other and form molds which are filled with the reaction components. As an example, Figure 7 shows a salt block 21a formed with a recess 72, which represents the shape of the desired cutting plate with the addition of the thickness of the protective metal casing 73. The recess 72 is lined with protective casing metal 75 (for example zirconium) as shown in Figs. contains a preformed cemented carbide body (or mass of sinterable carbide powder) 74, a mass of finely divided crystals of cubic boron nitride 76 and sheets (or powder) of aluminum and the metal to be alloyed with aluminum.

Salt 2lb cover block is provided with recesses to receive a cover 77 which completes the protective metal casing, and preferably a sintered carbide SC backing block to reduce the puncture of the protective metal casing layer 77. A number of such cooperating pairs of salt blocks, for example 2la, 2lb can be used together with the described content.

In the cutting plate structure 40 shown in Figure 5, the two surfaces 41 and Ä2 of the cemented carbide member 45 and the cubic boron nitride composite body Ä4 are formed with release (Figure 4) to facilitate the application of the cubic boron nitride cutting edge of the cubic composite body 44. boron nitride against the workpiece. ay In producing the thin layers 51, 61 of consolidated cubic boron nitride (about 90-97% by volume) in the cutting plate structures 52, 62 shown in Figures 5 and 6, the layer of fine-grained x cubic boron nitride is limited to a maximum thickness of about . 1.5 mm and a minimum thickness of approx. 0.025 mm, although it is possible to produce such layers with a thickness of up to approx. 2 mm. The purpose of making these layers 51, 61 very thin is to a) use the layers 51, 61 of cubic boron nitride as chip breaking surfaces, b) to make it easier to sharpen the cutting plates 52, 62 and c) to save on used cubic boron nitride.

Ideally, the ratio of the amounts of the layer of cubic boron nitride to the cemented carbide is such that the edge of the cubic boron nitride wears away slightly less rapidly than the cemented carbide part. If these conditions are maintained, a small portion of the layer of cubic boron nitride will continuously protrude beyond the cemented carbide body and give a cutting edge, and the amount of cubic boron nitride used will be proportional to the life of the tool. As stated above, when bonding cubic boron nitride with a size exceeding SOF m (as the largest dimension), the use of aluminum alloy as a binder can be dispensed with. In such a case, the method used is effective in providing satisfactory interconnection of crystals of cubic boron nitride with a dimension of 30 .mu.m (as the largest dimension) and smaller, probably due to the larger impurity content remaining concentrated on the larger outer surface of such small particles. For such purposes, at which a size of the cubic boron nitride in excess of 80 .mu.m is acceptable, the aluminum alloy used above as a binder may be omitted.

Figure 8 shows an arrangement for producing a plurality of sheet or tablet-shaped composite bodies (cemented carbide substrate with a layer of sintered cubic boron nitride on the substrate) in the absence of aluminum alloy as binder. The charge unit 50 (a) is not shown on the same scale as the device in Figure 1 but fits into the space jl in this device.

The charge unit 30 (a) consists of a cylindrical sleeve 32 (a) of casing metal which may be zirconium, titanium, tantalum, tungsten and molybdenum. The cylindrical sleeve 52 (a) of casing metal is provided with a number of subassemblies which are protected at the top and bottom with casing metal plates 53 (a) of any of the foregoing metals used to make the sleeve 52 (a) with the un dantag specified below. Each subunit thus protected on all sides consists of a larger mass jH (b) and a smaller mass 36 (a). Each pulp 36 (a) is wholly or predominantly composed of cubic boron nitride powder (with a maximum dimension exceeding about 80 mm).

By using a sintered cemented carbide plate such as pulp 34 (b) and pure crystals of cubic boron nitride larger than approx. 0.1 mm mm 7208677-0 12 (120 mesh US Sieve) as pulp 36 (a) without further additives, a simple abrasive body can be prepared as described below, the portion of cubic boron nitride being substantially free of voids and is joined to the cemented carbide plate with an exceptionally good bond.

Example 10.

Mainly pure cubic boron nitride with a grain size of approx. 0.19 mm (100 mesh) was distributed as a mass over a surface of a hard sintered carbide sheet made of grade 883 Carboloy (R) carbide powder. The material combination was enclosed in a thin zirconium casing to exclude and dispose of oxygen. This unit was in turn surrounded by NaCl elements (to fill volume 31) in a high pressure device.

After approx. For 1 hour under the influence of high pressure and high temperature (55-60 kb and 150,000), an abrasive composite body was recovered.

The portion of cubic boron nitride was found to be substantially free of voids, and an extremely good bond was found to exist between the cemented carbide and adjacent cubic boron nitride.

The composite body of Example 10 was examined and it was found that the substantially complete freedom from voids in the mass of cubic boron nitride (99% by volume cubic boron nitride) had been achieved by a number of mechanisms: a) penetration of zirconium metal (from the casing) to a shallow depth , for example 0.2 mm; b) crushing the cubes of cubic boron nitride (which can then be consolidated); c) penetration of carbide material between the grains of cubic boron nitride during the high temperature treatment (when the carbide material is present; 1 plastic state) and _ d) direct bonding between the grains of cubic boron nitride.

- The grains of cubic boron nitride had a large contact surface with each other and appeared to have been partially deformed plastically to adapt in shape to each other. In order to maintain the advantages of a mechanically unstable design of the charge unit, the discs 37 (a) are made of the same material as the cylinder 19, for example NaCl, hexagonal boron nitride, to give the required "filling" effect and fill the reduced the volume of each subunit during the process.

In the stated embodiments of the invention, sinterable carbide powder, as indicated below, may be used in place of the sintered carbide as pulp 4 (b). In such a case, sintering of the carbide powder takes place in situ.

The direct bond provided between the cubic boron nitride material with very high strength and the substantially larger mass of underlying, rigid carbide backing material necessitates the use of an intermediate adhesive layer applied, for example, by brazing or soldering. By using a rigid, non-resilient substrate material in direct contact with the cubic boron nitride rich cutting edge portion, the tendency to crack the cubic boron nitride material during the use of the cutting plate is reduced.

When using the embodiment with aluminum alloy as binder or the embodiment without such binder, composite bodies produced according to the invention have in some cases been inadvertently broken during the pressure drop in the reaction vessel to recover the product. This type of rupture takes place in a direction which is substantially perpendicular to the vertical axis of the charge unit.

In the case of composite bodies manufactured with subunits according to Figure 2 and Figure 8, the interface between the cubic boron nitride and the cemented carbide 1 is in the same direction. The high quality of the bond at this interface is evident from the fact that fractures usually occur through the layer of cubic boron nitride. Rarely do fractures occur at the interface, and in these cases the fracture surface was irregular and passed through the cubic boron nitride and cemented carbide as well as along the interface. Thus, the interface is generally stronger than the yield strength of the cubic boron nitride crystals.

Microscopic examination (30OX) of polished edges of composite bodies formed into cutting plates according to the specified embodiments has shown the reason for this unusually strong bonding at the interface.

In "good bonding" the grains of cubic boron nitride at the interface (at the degree of magnification 300X) appear to either be in direct contact with the sintered carbide or a thin reaction layer appears to be applied between the grains of cubic boron nitride and the sintered carbide.

The healing layers have a thickness of less than 10; 1m, which shows that in all cases a minimal decomposition of and attack on the cemented carbide structure takes place. The interface is free of voids and is irregular in micrometer scale (1-100 .mu.m) due to cubic boron nitride being pressed into the cemented carbide and / or plastically deformed cemented carbide moving into spaces between adjacent cubic boron nitride crystals.

This type and quality of interlaced interfaces cannot be obtained by brazing a preformed cubic boron nitride compact to a cemented carbide disc.

The manufacture of cubic boron nitride compacts for use as abrasive elements in cutting and abrasive machining tools is disclosed in the aforementioned U.S. Patents. After production, the press body is attached to some kind of substrate. These patents do not contain any information which could lead a person skilled in the art to produce a composite cutting plate in which the cubic boron nitride compact in the production is simultaneously joined to a cemented carbide substrate in accordance with the invention without the use of additives.

In addition to the type of composite body described above in which a mass of cubic boron nitride crystals is supported and bonded to a preformed cemented carbide mass, two other types of composite bodies can be produced. These two types of composite bodies have a relatively uniform distribution of cemented carbide in a mass of abrasive grains. In the second type of composite bodies, the abrasive grains are made of cubic boron nitride grains, and in the third type of composite bodies, the abrasive grains are a mixture of cubic boron nitride grains and diamond grains.

Example ll. e A mixture of 94% by volume of cubic boron nitride grains and 6% by volume of Carboloy grade 883 carbide powder (6% Co, 94% WC) was enclosed in a thin Zr casing (for exclusion and removal of oxygen).

This unit was introduced into a high pressure and high temperature device of the type described in Example 10. The mixture was subjected to a pressure of approx. 55 kb and a temperature of 1500 ° C for approx. 60 minutes time. Microscopic examination of polished surfaces of the resulting composite body showed that the sintered carbide had moved into most of the very small cavities between the grains of cubic boron nitride. Although direct bonding between the grains of cubic boron nitride was not obtained on a larger scale in this type of composite body, the bonding between cubic boron nitride and metal (carbide) was very good. A fracture surface of the composite body showed very few places at which a grain of cubic boron nitride had been withdrawn from the system. The grains of cubic boron nitride had broken in one place. No reaction layer could be observed next to the cubes of cubic boron nitride at the magnification EOOX. For the production of this type of composite body, a content of crystals of cubic boron nitride of approx. 70-94 volume%. With this high content of cubic boron nitride, direct contact is obtained between the crystals of cubic boron nitride under the influence of high pressure. As a result, crushing of the grains is obtained, and a large proportion of the original voids are filled with broken grains of cubic boron nitride. Penetrating carbide powder seems to prevent direct bonding between the grains of cubic boron nitride, but the bond between cubic boron nitride and carbide gives a tough, strong abrasive body. In carrying out the invention, the carbide powder, if used, preferably consists of tungsten carbide powder intended for molding (mixture of carbide powder and cobalt powder) which is commercially available with particle sizes from 1-5 m. The tungsten carbide can, if so, desired, replaced in whole or in part with titanium carbide and / or tantalum carbide. Since some use of nickel and iron has taken place in the bonding of carbide materials, the material used to make the metal binder in the cemented carbide may be cobalt, nickel, iron or mixtures of these metals. However, cobalt is preferred as the metal binder. The composition of carbide forming powders suitable for carrying out the invention may comprise mixtures containing approx. 75-97% carbide and approx. 3-25% bind medium metal. Examples of carbide powders used are "Carboloy grade 883" (6% Co, 94% WC) and "Carboloy grade 905 (5% co:% wc: 75 Tac: 0:15 ø Tic) type carbide. above, in the manufacture of composite cutting plates according to Figures 9, 5 and 6 and in the manufacture of any of these non-cylindrical shaped bodies, a modified construction of the salt liner 21 and the plugs 22, 22 'is required. The unit fitted in the heating tube 20 can thus constituted by a series of cylindrical blocks stacked on top of each other, so that they form molds which are filled with the constituents, for example a mixture of carbide forming powder and grains of cubic boron nitride.As an example, Figure 11 shows a salt block 21l (c) provided with a recess 72 (a) corresponding to the shape of the desired cutting plate with the addition of the thickness of a protective metal casing 73 (a) The recess 72 (a) is lined with a protective metal casing 73 (a) (for example zirconium), such as shown in the figure, - to contain the materials to be formed into a composite body. Covering salt block 21l (d) is provided with recesses intended to contain cover plate 74 (a) which completes the protective metal core, preferably a base block of cemented carbide SC, in order to reduce the puncture of the protective metal casing layer 74 (a). A number of cooperating pairs of salt blocks, for example 2l (c), 2l (d), can be used to fill the volume 31.

In a cutting plate structure 40 (a), shown in Figure 9, the two surfaces 41 (a) and 42 (a) of a cemented carbide / abrasive grain composite body 43 (a) are formed by release (Figure 10) to facilitate the application to the workpiece of the cubic boron nitride cutting edges. -7208677-o 16 If desired, the majority of the tool body 40 (a) may be cemented carbide (either preformed or made in situ) with only the area forming and adjacent the site 44 (a) made of the cemented carbide material / abrasive grains.

According to the embodiment in which aluminum alloy is not used as a binder, in the production of the thin layers g 51, 61 of consolidated cubic boron nitride (about 99% by volume) in the cutting plate structure 52, 62 in Figures 5 and 6 the grain is of cubic boron nitride limited to a maximum thickness of approx. 1.0 mm and a minimum thickness of approx. Q, 1 mm; but it is possible to produce such layers with a thickness up to approx. 2 mm.

After the treatment at high temperature and high pressure is completed, first the temperature is lowered and then the pressure. After the cutting plate masses have been recovered, the metal protective cover remains strongly bonded to the outer surfaces. Exposure of the desired surfaces of the composite cutting plate is easily achieved by sanding off the protective cover. 'It has been shown that the system can absorb small amounts of additives, such as tungsten and beryllium.

Example 12.

Two subunits were inserted into the volume 51 (at the upper and lower ends) in a high pressure and high temperature device. Each subunit was enclosed in a Zr beaker (diameter 6.4 mm) and consisted of a cemented carbide plug "B85 grade Carboloy" (thickness 1.27 mm) and a mass of 0.125-0.149 mm cubes of Cuban boron nitride. (0.065g) Only in the lower subunit were the cubes of cubic boron nitride covered with a thin layer of Ta metal applied by cathodic sputtering (sputtered) .The subunits were simultaneously subjected to a pressure of 55 kb and a temperature of ° C for 60 minutes, after which the subunits were recovered, polished and examined under microscope.

The upper subunit exhibited extensive direct bonding between cubic boron nitride grains, giving a strong abrasive body. Furthermore, there was also very good adhesion of grains of cubic boron nitride to the cemented carbide. The lower subunit (Ta-coated cubic boron nitride) showed many areas in which the grains of cubic boron nitride were sintered to each other. Other crystals of cubic boron nitride were bonded to the Ta-'7208677-0 17 matrix. Good bonding of the system cubic boron nitride / Ta to the cemented carbide was obtained.

Example 13.

A unit similar to the subunits of Example 12 was prepared. A Zr beaker (wall thickness 0.051 mm, diameter 6.4 mm) as a casing was charged with a body (0.5 g) of cold pressed carbide powder "885 grade Carboloy", and in contact with A mixture of cubic boron nitride with a particle size of 400 mesh (0.060 g), B83 grade Carboloy powder (0.02 l g) and Be powder (0.003 g) was applied to the surface of this body. The unit was simultaneously exposed to a pressure of 56 kb and a temperature of 152000 for 60 minutes.

A composite sheet with a cemented carbide base (thickness 1.78 mm) was obtained on one side with a layer of consolidated cubic boron nitride (thickness 0.71 mm) and a uniform diameter of 5.9 mm. Strong bonding was observed between the grains of cubic boron nitride and cemented carbide and direct bonding cubic boron nitride / cubic boron nitride.

The composite bodies produced according to the invention are usually used bonded to larger bodies, for example tool shafts or drill rods, which are used to apply the composite bodies to the material to be machined or cut.

Claims (15)

'7208677-0 18 PATENT REQUIREMENTS 1. A hard material composite body, in particular for abrasive or cutting tools, comprising crystals of cubic boron nitride and cemented carbide material, characterized in that the composite body comprises separate bodies which are strongly bonded to each other, a first of these bodies being constituted by metal-bonded cemented carbide carbide and a second is a polycrystalline body of cubic boron nitride crystals containing more than 70% by volume of cubic boron nitride crystals bonded to each other. 2. A composite body according to claim 1, in particular a cutting body or cutting plate for cutting machining, characterized in that a cutting edge is formed in the body of cubic boron nitride and that the body of metal-bonded hard metal carbide is formed as a force-absorbing substrate for the body of cubic boron nitride. 3. A composite body according to claim 1 or 2, characterized in that the body of cubic boron nitride also contains metal-bonded cemented carbide and / or diamond particles. Composite body according to one of the preceding claims, characterized in that the body of cubic boron nitride is bonded to the cemented carbide body along an interface which is substantially free of pores and cavities and wherein the cemented carbide or binder alloy fills the gaps with a size of about 1 - 100 .mu.m, which is formed between the interfacial crystals of cubic boron nitride so that the body of cubic boron nitride is bound and locked to the cemented carbide body. Composite body according to one of the preceding claims, characterized in that the body of cubic boron nitride crystals contains a metal phase containing aluminum atoms and atoms of at least one alloying element, which consist of one or more of the metals nickel, cobalt, manganese, 7208677 -0 19 iron, vanadium and chromium, the total amount of aluminum and alloying elements exceeding 1% by weight of the amount of cubic boron nitride. 6. '6. Composite body according to one of the preceding claims, characterized in that the individual crystals of cubic boron nitride have a largest dimension of less than about 30 .mu.m and preferably less than about 10 .mu.m. A composite body according to any one of the preceding claims, characterized in that the body of crystals of cubic boron nitride has a thickness of about 1.5 mm or less. Composite body according to one of Claims 1 to 5 or 7, characterized in that the content of crystals of cubic boron nitride in the boron nitride body exceeds about 90% by volume and preferably amounts to at least about 99% by volume. Composite body according to one of the preceding claims, characterized in that the cemented carbide is based on tungsten carbide and cobalt. 10. A process for producing a hard material composite body according to any one of the preceding claims, characterized in that in a protective metal casing (a) a separate quantity of sinterable cemented carbide powder containing binder metal and cemented carbide or a sintered carbide is placed carbide carbide carbide metal body and a separate quantity of cubic boron nitride crystals, or a polycrystalline body of cubic boron nitride crystals, which on subsequent pressure sintering produces a separate body containing at least 70% by volume of cubic boron nitride, (b) exposing the casing and its contents for the simultaneous action of a temperature of 1300-1600 ° C and a pressure exceeding about 40 kilobars for at least 3 minutes, (c) terminates the heat supply to the casing, (d) removes the pressure from the casing and ( e) utilizes the prepared hard material composite body. 11. ll. Process according to Claim 10, characterized in that the body of cubic boron nitride crystals contains a metal phase containing aluminum atoms and atoms of at least one alloying element, which consists of nickel, cobalt, manganese, iron, vanadium and chromium, the total amount aluminum and alloying elements exceed 1% by weight of the amount of cubic boron nitride. 12. l2. Process according to claim 10 or 11, characterized in that the crystals of cubic boron nitride are applied as a layer on at least one surface of the body of cemented carbide or sinterable powder of binder metal and cemented carbide, the layer having a thickness of 1.5 mm or less. 13. l3. Process according to Claim 11, characterized in that the material used as the source for an aluminum alloy is in powder form or in the form of sheets comprising a sheet of aluminum. 14. A method according to any one of claims 10 to 13, characterized in that the part of cubic boron nitride also contains diamond particles and / or cemented carbide. 15. A method according to any one of claims 10 ~ 14, characterized in that the cemented carbide body is based on tungsten carbide and cobalt. ANFÖRDA PUBLIKATIøNsR = sweden 224 733 (c22c 29 / oo), 370 931 (C043 31/16), 373 353 (co4B 31/16), 375 036 (co4B 31 16) Germany 1 169 333 (so b = 11/20 us 2,947,617 (51_3o7), 3,136,615 (51_3o7), 3,369,283 (29-95)