RU2491987C2 - Method of producing superhard composite material - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of carbon-based superhard composite to be used for making tools for mining, stone-working and metal working. Proposed method comprises applying high pressure and temperature to initial carbon component, a diamond, and binder. Note here that said carbon component comprises additionally fullerene and/or nanodiamond while said binder represents one or several components selected from the family including silicon bronze alloy, Monel metal, solid alloy. Superhard material is produced in two steps. At first step, the mix of initial components is subjected to dynamic pressure of 10-50 GPa at 900-2000°C. At second step, obtained material is placed in high-pressure vessel and subjected to static pressure of 5-15 GPa and heated to 700-1700°C for at least 20 seconds.

EFFECT: superhard micro hardness, high modulus of elasticity and higher wear resistance.

4 cl, 1 tbl, 2 ex

Description

The invention relates to the production of composite material, and in particular to a method for producing a superhard composite material based on carbon, which can be used for the manufacture of tools for the mining, stone processing and metal processing industries.

Currently, most of the leading firms in developed countries have switched to equipping rock cutting and metalworking tools with synthetic diamonds instead of natural diamonds. Much attention is paid to the creation of new composite materials, both based on well-known and on the basis of relatively recently discovered new modifications of carbon with other elements.

Known RF patent №2329947, IPC: СВВ 31/6, С04В 35/52, priority dated 10.24.2006, “Method for producing superhard polycrystalline material”. Initial components: diamond powders, including detonation diamond; the material for impregnation is silicon. The layers of diamond powder and impregnation material in contact are placed layer by layer on the charge. The layer of diamond powder is divided into two layers. In one of the layers, which is in contact with the impregnation material, diamond powder of diamond with particle sizes from 20/14 to 2/1 microns is used, and detonation diamond powder with particle sizes in the range from 1 to 100 nanometers is additionally introduced into it. In the second layer in contact with the first, diamond powder is used with particle sizes in the range from 40/28 to 28/20 μm, the height of this layer relative to the first being from 2: 1 to 3: 1. Silicon or materials containing it, for example, a mixture of silicon powders, flake graphite and detonation diamond, are used as the impregnation material. The workpiece is affected by a pressure of 3-8 GPa, a temperature of 1200-2000 ° C, for 40-120 seconds. The resulting material can be used to make a cutting tool.

The disadvantages of the proposed method are:

- instability of properties throughout the volume of samples;

- difficult to infiltrate the binder component in the workpiece from nanodiamonds.

A known method of producing new superhard materials from fullerene S-60 in accordance with the patent of the Russian Federation No. 2127225; СВВ 31/06, priority from 10/11/1996 "Superhard carbon material, method for its preparation and product made from carbon material."

An allotropic form of carbon — fullerene C-60 — is used as the starting carbon material. The C-60 fullerene is exposed to a quasi-hydrostatic pressure of 7.5-37 GPa and a temperature selected in the range of 20-1830 ° C with a holding time of at least one second in high-pressure apparatuses: toroid type, Bridgman type anvil, etc. When exposed to the original fullerene pressure and temperature polymerization of molecules or fragments of fullerene molecules occurs. Depending on the apparatus used, the product is obtained in the form of films (in Bridgman anvils) or in the form of bulk samples using other types of apparatus. Compact material samples have high mechanical and electrophysical properties. For example, polymerized fullerene indenters can scratch the faces of diamond single crystals. Moreover, according to x-ray analysis, the structure of the obtained target product differs from the structure of diamond and depends on the parameter values during thermobaric processing of the starting material. The method allows, prior to polymerization, to form a product blank having a predetermined shape from the starting fullerene.

Despite the high mechanical properties of new superhard materials obtained from fullerene during its polymerization under conditions of high pressures and temperatures, the use of these materials in tools is difficult due to the low thermal conductivity.

A method for producing superhard particles from C-60 fullerene and a significant increase in the wear resistance of an iron-based material in the RF patent No. 21343473, with a priority of 05/07/1998, IPC СВВ 31/06, С22С 26/00, "Method for producing superhard carbon particles and wear-resistant bulk material containing these particles. "

The invention relates to powder metallurgy, in particular to the production of superhard carbon particles in the volume of iron-carbon alloys used for products operating under wear conditions. A method for producing superhard carbon particles up to 0.5 mm in size is proposed, which consists in pressing a mixture of iron and fullerite powders, synthesizing superhard carbon particles at high pressures and temperatures, and then extracting these particles, characterized in that the isostatic pressing is carried out at a low pressure of 2.5 -4.5 GPa and temperatures of 1000-1200 ° C. The invention also includes a wear-resistant material containing iron or carbon steel and superhard carbon particles up to 0.5 mm in size and in an amount of up to 20%. The technical result of the invention is to increase the size and quantity of superhard particles in the volume of iron-carbon alloys and to obtain a material with a wear resistance that exceeds that of the known X12M and stellite alloys.

The disadvantage is the limited use of the material in tools designed for rock cutting.

Known diamond is a carbon material and a method for its production (US Pat. No. 2359902, with priority from 12/30/2005 IPC. C01B 31/06, B82B 3/00) according to this invention, the diamond-carbon material contains carbon, hydrogen, nitrogen and oxygen moreover, the material contains carbon in the form of a diamond cubic modification and in the X-ray amorphous phase in the ratio (40-80) / (60-20) by weight of carbon, respectively, and while containing, wt.%:

carbon 89.1-95.2 hydrogen 1.2-5.0 nitrogen 2.1-4.8 oxygen 0.1-4.7 fireproof impurities 1.4-4.8

A method for producing this material involves detonation of a carbon-containing explosive with a negative oxygen balance in a closed volume of a gas medium inert to carbon surrounded by a condensed phase containing a reducing agent with a quantitative ratio of the mass of the reducing agent in the condensed phase to the mass of the used carbon-containing explosive not less than 0.01 :one. An inorganic or organic compound having reducing properties, preferably containing no oxygen atoms and halogens, is used as a reducing agent. To determine the elemental composition of diamond-carbon material, the material is subjected to exposure at a temperature of 120-140 ° C under a vacuum of 0.01-10.0 Pa for 3-5 hours and its subsequent processing at a temperature of 1050-1200 ° C with an oxygen stream speed, providing its burning within 40-50 s.

The material can be used in the manufacture of polishing and finishing compositions, film coatings, radiation-resistant materials.

The disadvantage of the proposed technical solution is its limited use.

The closest technical solution is a method of manufacturing a sintered diamond product with high wear resistance and high strength (Pat. RF No. 2347744 with priority dated July 26, 2005 IPC. C01B 31/06, C04B 35/52 "Sintered diamond product with high strength and high wear resistance and method of its manufacture ”). According to this technical solution, the sintered diamond product contains sintered diamond particles having an average particle size of at most 2 μm and a binder phase, as the remaining part, in which the content of said sintered particles in said sintered diamond product is at least 80 vol.% and at most 98 vol.%. The binder contains at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum, the content of which is titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum , the content of which is at least 0.5 wt.% and less than 50 wt.% and contains cobalt, the content of which is equal to at least 50 wt.% and less than 99.5 wt.%.

Sintering is carried out under pressure conditions in the range of at least 5.7 GPa, at most up to 7.5 GPa and a temperature in the range of at least 1400 ° C, and at most up to 1900 ° C, using an ultra-high pressure device Type "Belt".

The obtained products according to the prototype are characterized by high strength and high wear resistance, the product has a transverse tensile strength of at least 2.65 GPa, the amount of wear on the back surface of 39-65 microns. The invention can be used in the manufacture of cutting and processing tools, electrodes.

The prototype has a limitation on the use of composite materials obtained by this method for the manufacture of tools for drilling, stone processing, since the grains of the sintered material do not exceed 2 μm and cannot provide high performance during the operation of tools.

The objective of the proposed technical solution is to eliminate these drawbacks and obtain a carbon material with high microhardness, high elastic modules and increased wear resistance, which will allow the use of the material in the mining, stone processing and metal processing industries.

The problem is solved by exposure to high pressure and temperature on the initial carbon and binder components in two stages. At the first stage, a carbon component is taken, for example, diamond and a binder component are used, in addition, fullerene and / or nanodiamonds are used as the carbon component, and one or more components selected from the series are used as the binder component: silicon bronze, for example , BrKMts3-1; Monel, for example, NMZHMts; hard alloys, for example, TT7K.12. A mixture of a given composition is prepared from the components, then it is placed in a storage ampoule and subjected to a dynamic pressure of 10-50 GPa at a temperature of 900-2000 ° C in order to partially or completely convert fullerenes into dense superhard carbon modifications, activate chemical interaction between the components to obtain a compact material . As fullerenes take fullerene C-60 and / or C-70. The method of shock-wave exposure allows to obtain large blanks of composite material. Since the exposure process is short-term (fractions of a microsecond), the process of component consolidation in most cases remains incomplete.

The completion of the process of formation of the target product is carried out during the second stage. The samples of the material obtained in the first stage are subjected to a static pressure of 5 to 15 GPa and heated to a temperature of 700-1700 ° C for at least 20 seconds. At this stage, a complete transition of fullerenes into dense superhard carbon modifications occurs, and chemical bonds between the components are formed. Pre-carbon components can be coated with one or more binder components selected from the range: silicon bronze alloy, monel alloy, hard alloy. The result is a composite material with high microhardness, modulus of elasticity and a ratio of microhardness-modulus of elasticity of 0.15-0.16, which indicates a high wear resistance of the composite material.

When exposed to selected components of dynamic pressures of 10-50 GPa and temperatures of 900-2000 ° C, the parameters are selected experimentally. Going beyond the lower limits of these ranges does not lead to a significant conversion of fullerene, going beyond the upper limits leads to depressurization of the storage ampoules.

In the second stage, when the material obtained in the first stage is exposed to static pressures in the range of 5-15 and temperatures of 700-1700 ° C, the parameters are chosen experimentally. Going beyond the lower limits of the range does not allow to obtain high-quality samples of the material; going beyond the upper limits of the range does not improve the properties of the material, but reduces the service life of the devices. Excerpts on the mode for 20-180 seconds are optimal for obtaining the target product. The ratio of the components was established experimentally.

The method is confirmed by the following examples.

Example 1. Prepared a mixture of powders weighing 12 g, containing C-60 fullerene: 35% (wt.), Diamond grain size 100/80: 25%, Monel alloy powder (composition - Cu 27%, Fe 2.5%, Mn 1.8 %, (Ni + Co) - the rest): 40%. The mixture was pressed into a steel storage ampoule, which was closed with steel plugs from the ends. The 3rd layer of BB (plastid) was placed on the external walls of the conservation ampoule; blasting was carried out in a special device. The pressure during the shock wave action was 35–40 GPa, the temperature was 1500–1700 ° C. Then the ampoule material was mechanically removed and the contents of the ampoule were extracted in the form of a compact cylindrical sample. According to the results of density measurements and X-ray phase and electron microscopy analyzes, it was found that the initial carbon component of C-60 fullerene turned into a superhard modification of 83%.

At the second stage, in order to increase the mechanical properties of the composite material, a sample of the obtained material weighing 0.5 g was placed in the container of the anvil with holes type high-pressure apparatus, a pressure of 15 GPa was created, heated to a temperature of 1450 ° C, held for 90 seconds, cooled to 50 degrees, reduced the pressure to atmospheric and removed the sample.

The microhardness of the carbon components of the sample — 90–130 GPa, the microhardness of the boundaries of the binder component — the carbon component 48–64 GPa, was determined using sclerometry using the NanoScan device. To determine the elastic moduli, the velocities of longitudinal and shear sound waves were measured by the echo-pulse method using the focusing system of the WFPAM acoustic microscope, the density of the sample was determined by the hydrostatic method. It was found that the modulus of elasticity is 850 ± 43 GPa, the ratio of the maximum microhardness to the modulus of elasticity is 0.15, which is typical for materials with superelastic reduction ability and high wear resistance.

Example 2. Prepared a mixture of powders weighing 12 g, containing fullerene C-70: 30% (wt.), Diamond grain size 100/80: 20%, alloy powder VK-20: 50%. The mixture was pressed into a steel storage ampoule, which was closed with steel plugs from the ends. 3 layers of explosives (plastids) were placed on the external walls of the conservation ampoule; undermining was carried out in a special device. The pressure during the shock-wave action of 40-45 GPa, the temperature of 1500-1700 ° C. Then, the ampoule material was mechanically removed and the contents of the ampoule in the form of a compact sample of a cylindrical shape were extracted. According to the results of density measurements and X-ray phase and electron microscopy analyzes, it was found that the initial C-70 fullerene turned into a superhard modification of 70%.

At the second stage, in order to increase the mechanical properties of the composite material, a sample of the obtained material weighing 0.5 g was placed in the container of the anvil with wells type high-pressure apparatus, a pressure of 13 GPa was created, heated to a temperature of 1500 ° C, held for 90 seconds, cooled to 50 degrees, reduced the pressure to atmospheric and removed the sample.

The microhardness of the carbon components of the sample — 87–120 GPa, and the microhardness of the boundaries of the binder component — the carbon component 47–62 GPa, were determined by sclerometry using the NanoScan device. To determine the elastic moduli, the velocities of longitudinal and shear sound waves were measured by the echo-pulse method using the focusing system of the WFPAM acoustic microscope, and the density of the sample was determined by the hydrostatic method. It was found that the elastic modulus is 780 ± 39 GPa, the ratio of the maximum values of microhardness to the elastic modulus is 0.15.

Table 1 shows examples Nos. 3, 4, 5, which indicate the parameters (P, T, τ) of the impact at the first stage of the dynamic and at the second stage of static pressure on the mixture of the selected components, as well as the values of microhardness, elastic modulus and the ratio microhardness is the elastic modulus for their maximum values. The sequence of technological operations as in examples No. 1, 2.

The choice of starting components, including С-60, С-70 fullerenes, as well as binding components, the process in two stages, allows to obtain an ultrahard composite material with high wear resistance, suitable for use in the mining, stone processing and metal processing industries.

Table 1 No. p / p The composition of the components of the mixtures Dynamic pressure: P, GPa; T, ° C. Static pressure: P, GPa; T, ° C; τ second Microhardness (V), GPa Modulus of elasticity (E), GPa V / e 3 C-60: 20%, diamond 250/200: 40%, nanodiamond: 10%, silicon bronze - BrKN1-3: 30% P-20; T-1400 P - 10.5; T - 1350; τ - 180 61-88; 39-41 520 0.16 four S-60: 25%, diamond (400/315 - 30% + 40/28 - 20%), nanodiamonds - 15%, TT7K.12 alloy - 30%. P-25; T-1200 P - 14; T - 1500; τ - 20 80-102
30-35 697 0.15 5 S-60: 20%, diamond 250/200 (coated with a layer of BrKN1-3): 70%, nanodiamond: 10% P-20; T-1400 P - 12; T - 1350; τ - 180 75-97
48-57 589 0.16

Claims (4)

1. A method of obtaining a superhard composite material, including the action of high pressure and temperature on the initial carbon component, which is used as a diamond and a binder component, characterized in that the carbon component further comprises fullerene and / or nanodiamonds, and one or several components selected from the series: silicon-bronze alloy, monel alloy, hard alloy, the preparation being carried out in two stages, in the first stage, a mixture of the starting components in apply dynamic pressure of 10-50 GPa at a temperature of 900-2000 ° C, in the second stage the resulting material was placed in a pressure vessel and exposed to static pressure from 5 to 15 GPa, and heated to a temperature of 700-1700 ° C for at least 20 seconds. 2. The method according to claim 1, characterized in that fullerene C-60 and / or C-70 is used as an additional carbon component. 3. The method according to claims 1 and 2, characterized in that the carbon components are pre-coated with one or more binder components. 4. The method according to claim 1, characterized in that as a binder component they take an alloy of silicon bronze of the BrKMts3-1 brand, or a monel alloy of the NMZhMts brand, or a solid alloy of the TT7K.12 brand, or a hard alloy of the VK-20 brand.