RU2538551C1 - Diamond polycrystalline composite material with reinforcing diamond component - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to diamond-based composite materials, obtained by sintering diamond grains and metals with dispersion-strengthening additives and reinforcing CVD diamond component in form of insert, modified under conditions of high pressure and temperature, and can be used for production of drilling and dressing tools. Diamond semi-crystalline composite material with dispersion-strengthening additive contains refractory shell, in which powders of diamond, metal and CVD diamond insert are placed. Shell is made of refractory metal, mainly tantalum and niobium. Nickel, cobalt are used as metals, and tungsten carbide nanopowder is used as dispersion-strengthening additive with the following component ratio, wt %: diamond powder and CVD diamond insert 85-90, nickel 7-9, cobalt 2-4, tungsten carbide nanopowder 0.1-3.0.

EFFECT: increase of hardness and wear-resistance of reinforced with CVD diamond sintered composite and reliable fixation of material in drilling instrument.

1 ex, 1 tbl

Description

The invention relates to the field of production of polycrystalline materials, namely to composite materials based on diamond obtained by sintering diamond grains and metals with dispersion-reinforcing additives and CVD reinforcing diamond components in the form of an insert modified under high pressure and temperature, and can be used mainly for the manufacture of drilling and ruling tools.

Polycrystalline materials are known, the diamond layer of which can be created from a mixture containing 75-85% of strong grains (A.S. USSR 1425984, class B24D 3/06, B22F 3/10, publ. 14.01.87); the diamond layer or part thereof may contain individual solid polycrystalline aggregates that are distributed in its volume (US Patent Application 20080073126, Е21В 10/46, B01J 3/06, C01B 31/06, published March 27, 2008) or contain heat-stable solid regions ( US Patent Application 20110056142, E21B 10/36, publ. 30.11.2006). In the technical solution (US Patent Application 20060266558, B24D 11/00, published March 10, 2011), pre-sintered diamond carbide granules are introduced into the diamond layer. Such a granule consists of a single crystal of diamond with a size of ≈ 800 μm, located in its central part, around which there are 20-30 grains with a size of 300-400 microns.

The hardness of the diamond layer of polycrystalline materials created in ISM and V.N. Bakul, is 50 GPa (VG Gargin. Physical and mechanical properties of diamond carbide inserts // Polycrystalline materials based on synthetic diamond and cubic boron nitride. - K .: ISM AN USSR, 1990. - P. 62-67), General Electric Stratapax plates — 50-63 GPa (Stratapax drill blanks. Open a new world of mining. Specialty material department. General electric company. Worthington. OHJO43085), De Beers Sindrill plates — 50 GPa ( Latest Product Sindrill De-Beers Synthetic Polycrystalline Diamond Drill Blank. - Indiagua, 1983. - P. 43-44).

Recently, the technology of diamond deposition from the gas phase (CGFD - chemical gas-phase deposition, or CVD - Chemical Vapor Deposition) has been actively developed, in which, as a rule, mixtures of methane and hydrogen serve as the reaction medium.

There are well-known companies that grow various CVD diamonds from the gas phase: “light” (with a small content of defects), which are mainly used in electronics, and “black” (black diamond), with a high concentration of defects, which are used as tool materials. Element Six produces black diamonds of several grades, for example, graphite-free CDD. The so-called “black diamond” is a polycrystalline CVD diamond with a high content of structural defects, such as microtwins, dislocations, and nanometer amorphized domains [L. Nistor, J. Van Landuyt, V. Ralchenko and I. Vlasov, "Structural aspects of CVD diamond wafers grown at different hydrogen flow rates", Physica Status Solidi (a), 174 (1999) 5-9]. These defects cause strong optical absorption in the "black" diamond, while graphite inclusions are absent in them. However, during vacuum annealing of polycrystalline diamond, even initially transparent, to temperatures above 1200–1300 ° C, thin layers of crystallized graphite with a thickness of several interplanar spacings can form at grain boundaries [V. Ralchenko, L. Nistor, E. Pleuler, A. Khomich, I. Vlasov and R. Khmelnitskii, Structure and properties of high temperature annealed CVD diamond, Diamond and Related Materials, 12 (2003) 1964-1970.], Which also leads to blackening of the material.

According to the firm ((Diamond Materials Gmbh »(http://www.diamond-materials.com/DE/cvd_diamond/overview.htm), the hardness of CVD diamonds is between 75 and 110 GPa. In the application for the grant of US patent No. 10 / 889169 shows data on the hardness of CVD diamonds, which is 50-90 GPa, and fracture toughness 11-20 MPa · m ^1/2 .

When heat treated at high pressure (p = 5 GPa, T = 1800-2500 K), the hardness of a CVD diamond single crystal reaches 160-180 GPa (Pat. Appl. 20030230232 US. IPC С23С 016/27; с30D 021/02; С30D 028 / 06; C23C 016/00. Method of making enhanced CVD-diamond / RH Frushou, W. Li; Appl. 12/18/03).

After barothermic processing of “white” polycrystalline CVD diamond at a lower temperature (1570 K) and a pressure of 8 GPa in the process of obtaining a hybrid diamond-silicon carbide composite material, its hardness increased by 80% (Shulzhenko A.A., Ashkinazi E.E., Sokolov AN, et al. New hybrid ultrahard material // Superhigh materials. - 2010. - No. 5. - P. 3-14).

Single crystals of CVD diamond (SC-CVD) after annealing at pressures of 5-7 GPa and temperatures of 2000-2700 ° C have a hardness of 100-160 GPa and crack resistance up to 40 MPa · ^1/2 (US patent 2389833, class C30B 25 / 00. Published on October 27, 2008).

The wear resistance of the material is determined by direct tests - time-consuming and expensive, but it can be predicted on the basis of physical and mechanical characteristics. Comparison of the experimental and calculated by the formula S = Hv ^1/2 -K _1c ^3/4 (S is the parameter of wear resistance; H _v is the hardness of the material; K _1c is the crack resistance) of the data on wear resistance does not give any doubt about their correlation between themselves (Maistrenko A. L., Dub S.N. Prediction of the wear resistance of brittle materials by hardness and crack resistance // Factory Laboratory. - 1991. - 57. - No. 2. - P. 52-54).

The values of the wear resistance parameter thus determined by the formula for the diamond layer (H _v = 50 GPa, K _1s = 11.7 ± 1.4 MPa · m ^1/2 ) will amount to 45-51 conventional units. At the same time, polycrystalline CVD diamond (H _v = 100-160 GPa, K _1c = 11-20 MPa · m ^1/2 ) has a wear resistance parameter of 57-96, and single-crystal (H _v = 160 GPa, K _1s = 30-40 MPa · m ^1/2 ) - 162-200, i.e. CVD modified diamond insert has a significantly greater (about 4 times) wear resistance parameter.

Dispersion hardened composite materials (DKM) belong to the class of powder composite materials. The structure of a DCM is a matrix of pure metal or alloy in which finely dispersed particles of the strengthening phase less than 0.1 μm in size are artificially introduced into the material at one of the technological stages and distributed at a given distance from one another. The volume fraction of these particles (inclusions) is 0.1-15%. As the hardening phase, dispersed particles of oxides, carbides, nitrides, borides and other refractory compounds, as well as intermetallic compounds, are used.

The closest in technical essence to the proposed method is the method (see application SU 4122626/26, IPC СВВ 31/06, publ. 09/27/1999) for producing a polycrystalline material based on diamond under the influence of pressure and temperature on a charge of carbon material and metals - catalysts (aluminum and niobium) placed in a graphite shell. In this case, in order to ensure superconducting properties, the carbon material is taken in the stoichiometric ratio of carbon atoms to aluminum atoms, and niobium is taken in the amount of 4 atoms per 1 mol of the resulting compound Al ₄ C ₃ . The disadvantage of the material obtained according to the prototype is its insufficient hardness and wear resistance, since the task of the prototype was to obtain a superconducting material.

The basis of the invention is the task of such an improvement in diamond polycrystalline composite material, in which, thanks to the choice of the metals, additives, CVD diamond inserts, and their ratio, such technical effect is provided as increasing the hardness and wear resistance of the sintered composite reinforced with CVD diamond, and by selecting a refractory the shell provides reliable fastening of the material in the drilling tool. The use of refractory metals as a shell material, such as Ta, Nb, etc., is due to the fact that after sintering, the shell and the diamonds, metals and additives located in it are one, thereby increasing the strength of the obtained insert, and when fixing the inserts from the specified material, the soldering process is facilitated, since the shell is wetted with the used solders, while the process of metallization of the inserts is excluded. In addition, during sintering, for example, inserts of a drilling tool from the specified material, in the graphite multiposition high-pressure cells, the formation of diamond around the sample from the material and the occurrence of defects in its shape are excluded.

The introduction of dispersion-strengthening additives contributes to the production of such a composite material in the metal matrix of which finely dispersed particles of an additional substance are uniformly distributed. In such materials, the CVD diamond insert and matrix take up the entire load during loading, in which, using a multitude of particles of the 2nd phase that are practically insoluble in it, a structure is created that effectively resists plastic deformation.

In addition, with the help of particles of the 2nd phase, the process of microcrack formation is suppressed and, as a result, the matrix strength and the effect of barothermal action on the CVD diamond insert of the obtained polycrystalline composite material are increased.

This problem is solved in that in a polycrystalline diamond composite material with a dispersion hardening additive containing a refractory shell containing diamond, metal and CVD diamond inserts, according to the invention, the shell is made of refractory metal, mainly tantalum or niobium, and as metals nickel, cobalt are used, and additionally as a dispersion hardening additive — tungsten carbide nanopowder in the following ratio of components, wt.%

diamond powder and CVD diamond insert 85-90 nickel 7-9 cobalt 2-4 tungsten carbide nanopowder 0.1-3.0

The causal relationship between the set of features, which are also the technical results that are achieved during the implementation of the invention, is that a high level of physical and mechanical properties of a polycrystalline material is determined by the presence of a continuous framework between diamond particles and, first of all, the formation of a diamond-diamond bond, the formation of a finely divided grain structure, as well as crystal-oriented cubic and hexagonal (lonsdaleite) lattices in the structure is modified CVD diamond, increasing its hardness.

Metals such as nickel and cobalt, when sintering in grain boundaries, play the role of a technological environment in which the diamond-metal system interacts and undergoes a recrystallization process through the liquid phase, the source of which is nickel and cobalt. This leads to diamond-diamond bonds and an increase in the strength of the material. The introduction of cobalt and nickel increases the viscosity of the material (reduces its brittleness) and, accordingly, strength, which significantly increases the resulting barothermic effect on the CVD diamond insert contributing to the transformation of the crystal lattice. In addition, a nickel alloy with the addition of cobalt, under conditions of high pressure and temperature, better wetts diamond grains than only cobalt - this is clearly visible on the structure of the obtained sample from the material. The introduction of tungsten carbide nanopowders increases strength. The hardening of such materials consists in creating a structure in them that impedes the movement of the dislocation. Discrete particles of the second phase, for example, chemical compounds such as carbides, nitrides, borides, and oxides, which are characterized by high strength and melting temperature, create the strongest drag on the movement of dislocations.

In dispersion-hardened materials, the specified strength and reliability are achieved by the formation of a certain structural state in which the effective braking of dislocations is combined with their uniform distribution in the bulk of the material or (which is especially favorable) with a certain mobility of the dislocations accumulating at the barriers to prevent brittle fracture. In such a material, as in powder composite materials, the matrix carries the main load.

Examples of specific implementation of the invention

For hardness tests, samples were obtained with a diameter of 4 mm and a height of 4 mm reinforced with CVD diamond inserts. A 0.5 mm thick polycrystalline CGFO diamond was deposited in a mixture of methane with hydrogen in a microwave plasma on a 57 mm diameter Si substrate on a UPSA-100 installation (microwave power 5 kW, frequency 2.45 GHz) [Ralchenko VG, Savelyev A .V., Popovich A.F., Vlasov I.I., Voronina SV., Ashkinazi E.E. Two-layer heat-conducting dielectric substrates diamond - aluminum nitride. Microelectronics, 2006, v. 35, No. 4, p. 243-248]. Typical synthesis parameters of the “opaque” CVD diamond of tool quality were: gas pressure in the chamber 95-100 Torr, CH4 concentration in the mixture 10%, substrate temperature 850-870 ° C, deposition rate ~ 5.0 μm / h. The resulting diamond plate was separated from the substrate by chemical etching in an acid mixture, and then using a laser cutting machine (YAG: Nd laser, λ = 1.064 μm), 4.0 × 1.0 × 0.5 mm plates were cut from it (length x width x thickness). The samples were sintered in a toroid type high-pressure apparatus with a central recess diameter of 30 mm. To produce samples of a diamond polycrystalline composite material, multi-position graphite heaters with a diameter of 18 mm and a height of 5 mm, with cylindrical holes with a diameter of 4.5 mm, were pressed. A 0.05 mm thick shell of refractory niobium metal, a powder charge, and CVD diamond inserts were placed in cylindrical holes. When using a shell with a thickness of less than 0.02 mm during sintering, diamond grains can penetrate through it, as a result of which separate sections are formed, which remain impregnated when soldering the inserts into the tool body. A shell with a thickness of more than 0.15 mm is impractical to use, due to a decrease in the diameter of the inserts from the resulting material, and a larger amount of material of low wear resistance. A preliminary mixture of nickel, cobalt and nanopowder WC tungsten carbide metals was made.

As you know, effective ways to create a dense, homogeneous structure of polycrystals, which provides a high level of physical and mechanical properties, is to use methods of preliminary preparation of the starting materials in combination with the sintering process (or synthesis) at the maximum possible pressures.

One of the most important preparatory operations is mixing, which means the preparation with the help of mixers of a homogeneous mechanical mixture of metal powders of various chemical and granulometric composition or a mixture of metal powders with non-metallic. Only a uniform distribution of particles of one powder among particles of another will ensure uniform properties in different products.

Obtaining a homogeneous mixture from powders of different compositions is one of the most difficult tasks of chemical technology, which is even more complicated if it is necessary to mix powders with different particle sizes - during the mixing process, larger particles will be collected in one part of the volume of the mixture, and small ones in the other.

Therefore, obtaining a homogenized mixture was provided as a result of using two mixing techniques.

At the first stage, weighed components were placed on a molybdenum plate and thoroughly mixed manually with a metal spatula.

The quality of the mass mixing was checked visually under an MBS-6 microscope at a magnification of × 100 when pressing with a spatula on a mixture sample selected by quarting. A mixture consisting of a mixture of the same color ingredients should not contain shiny particles (not crushed crystals), and powders containing also colored substances should not have noticeable inclusions of colored particles.

The second stage of preparation of the charge was the use of a device for mixing with mixing rolls ЕХАКТ 501 manufactured by ЕХАКТ Advanced Technologies GmbH (Germany), in which solid active ingredients are processed uniformly and finely through three ceramic rolls rotating towards each other with separately adjustable roll gaps. so that the final product is deaerated and lumps of powder are minimized.

Thanks to the open roll system, the process of homogenization and dispersion can be directly controlled. The size of the crushed particles for various substances is set by the size of separately adjustable gaps between ceramic rollers. Double processing of the charge on a three-roll machine EXAKT 501 leads to the dispersion of nickel, cobalt and homogenization of the charge (Co, Ni, WC).

The resulting mixture was mixed with diamond powder with a grain size of 40/28. It is advisable to use diamond powders with a grain size of 20-100 μm, the indicated grain size is optimal, that is, they have the necessary abrasion resistance and are well sintered to obtain the proposed composite material. The mixture obtained from diamonds, Ni, Co with WC was poured into a Nb shell, CVD diamond inserts were introduced and placed in a high pressure cell. Sintering was carried out at a pressure of 8 GPa, a temperature of 1900 K, and a heating duration of 90 s.

Example 1

By the described method, samples of a diamond polycrystalline composite material reinforced with CVD diamond were prepared, containing wt.%:

diamond powder and CVD diamond insert 87 nickel 8 cobalt 3 tungsten carbide nanopowder 2

Received samples of a polycrystalline composite material based on diamond powder and CVD diamond insert in a shell of refractory metal Nb with a diameter of 4.2 mm and a height of 4.2 mm Subsequently, grinding of samples of the material by diameter and ends with a free abrasive was carried out to obtain plane-parallel planes to eliminate errors in measuring hardness. On a PMT hardness tester, a Vickers indenter with a force of 50-100 N measured hardness in the central part of the matrix and in the center of the CVD diamond insert of each of the samples (10 pcs). The confidence interval for the hardness at a reliability coefficient of 0.95 did not exceed 0.2 GPa. The test results are shown in the table.

As can be seen from the table, examples 1-7, the use of the invention allows to increase the initial hardness CVD of the diamond insert from 78 to 125 GPa by modifying the composition of the APCM matrix i.e. ~ 65% without changing the barothermal sintering modes (see table). Examples 8-13 are outside the scope of the claimed features. The content of metal additives of nickel and cobalt, according to the upper limit (wt.%), Leads to the melting of their solutions from the shell. The content of WC additives according to the upper limit leads to defects in the material samples in the form of cracks, chips, etc. The content of cobalt additives, WC nickel according to the lower limit, leads to a decrease in hardness.

Table An object
test No. p / p The composition of the mixture of diamond powder and additives,
% (by weight) Hardness, GPa HPHT and CVD diamond Ni Co WC Agribusiness CVD diamond component Ref. After NRT The material according to the claimed invention one 87 8 3 2 78 78 122 2 86 9 3 2 80 78 124 3 88 7 3 2 76 78 120 four 88 8 2 2 71 78 115 5 86 8 four 2 75 78 121 6 86 8 3 3 81 78 125 7 88.9 8 3 0.1 68 78 112 8 84 eleven 3 2 Smelting Co-Ni-WC 78 105 9 85 8 5 2 Smelting Co-Ni-WC 78 one hundred 10 85 8 3 four The occurrence of individual chips and cracks 78 94 eleven 89 6 3 2 64 78 108 12 89 8 one 2 66 78 BY 13 88.95 8 3 0.05 65 78 111 Prototype fourteen fifty

Claims (1)

Polycrystalline diamond composite material with a dispersion hardening additive containing a refractory shell containing diamond, metal and CVD diamond powders in the form of an insert, according to the invention, the shell is made of refractory metal, mainly tantalum or niobium, and nickel, cobalt are used as metals and additionally, as a dispersion hardening additive, tungsten carbide nanopowder in the following ratio of components, wt. %:
diamond powder and CVD diamond insert 85-90 nickel 7-9 cobalt 2-4 tungsten carbide nanopowder 0.1-3.0