RU1775357C - Polycrystalline diamond producing method - Google Patents

Abstract

Usage: upon receipt of high-strength diamond polycrystals operating under conditions of high mechanical loads. SUBSTANCE: effect on ultrahigh pressure on a carbon material by heating in the field of thermodynamic stability of diamond, and diamond is used as a carbon material, which is pre-crushed to obtain isometric granules 1-100 μm in size, separated by fractions and purified from impurities with acid solutions: boiling chlorine (30-70%) for 10-20 hours, a mixture of salt (with a density of 1.19 g / cm ^, nitrogen (with a density of 1.40 g / cm '^ and distilled water in a ratio of 1: 1: 1 by volume for 2-4 hours, hydrofluoric (40%) for 1-2 hours, then washed with distilled boiling water with a three-time replacement for 0.5-1 hours and dried for 10-20 hours at 100-120 ° C. ≫ & w * -ё

Description

The invention relates to the field of producing high-strength polycrystals operating under conditions of high mechanical and thermal loads.

The closest in technical essence to the claimed is a method for producing polycrystalline diamonds that do not contain metal inclusions. This method is selected as a prototype. Its disadvantage is, like natural diamonds, insufficient mechanical strength.

The aim of the invention is to increase the strength and thermal strength of polycrystalline diamonds by activating the surface of the original diamond material and optimizing the properties of the crystals.

PRI me R 1 - Polycrystalline synthetic diamonds obtained according to

E2-E 1

prototype, fraction t at E

-. Grains 30/20 μm in size are isolated, boiled for 15 hours in a solution of 70% perchloric acid, (conc. 70%) for 3 hours in a mixture of solutions of hydrochloric and nitric acids, kept for 1 hour in a solution of hydrofluoric acid and boiled for three times for 45 minutes t in distilled water, dried for 15 hours at 110 ° C, poured into a cell with a diameter of 4 mm, a height of 4 mm or a cell with a diameter of 7 mm, a height of 5 mm, compacted, placed in a toroid type reactor with a hole diameter of 15 mm with a graphite heater , create a pressure of 9 GPa, heated to 1800 ° C, held for 20 s (or up to 2000 ° C and held for 1 -2 s). Get diamond polycrystal b form

a cylinder with a diameter of 3.5 mm, a height of 3 mm, or a diameter of 5.5 mm, a height of 3.5 mm, a resistance of more than Ohm cm, an ash content of less than 0.05 May. %, strength 6.5 GPa, thermal strength - unchanged, temperature not less than 1200 ° С, thermal conductivity 400 W / (m deg),

PRI me R 2. Joints and single crystals of natural diamond powder of metamorphic rocks are crushed at. Grains of 20/10 μm in size are isolated, boiled for 10 hours in a solution of 30% perchloric acid, 2 hours in a mixture of hydrochloric and nitric acid solutions, kept for 2 hours in a solution of hydrofluoric acid, boiled three times for 30 minutes in distilled water. then dried for 10 hours at 100 ° C, poured into a cell with a diameter of 12 mm and a height of 10 mm or a cell with a diameter of 18 mm, a height of 4 mm, compacted, placed in a toroid type pressure chamber with a diameter of 35 mm with a graphite heater, create a pressure of 8, 0 GPa, heated to 1500 ° C and held for 100 s (or 1800 ° C and 30 s). Obtained is a diamond polycrystal (compact) with a diameter of 10 mm, a height of 8 mm (or a diameter of 1 mm and a height of 3 mm), a resistance of more than Ohm cm, an ash content of less than 0.1 wt.%, A strength of 6.0 GPa, and heat resistance - unchanged to thermal conductivity 350 W / (m hail).

PRI me R 3, Druse (or polycrystalline aggregates) of natural diamond powder of volcanic (kimberlite) rocks, for example XX group, crushed at. Grains 100/80 μm or 30/20 μm in size are isolated, boiled for 20 hours in a solution of 30% perchloric acid, 4 hours in a mixture of hydrochloric and nitric acid solutions, kept for 4 hours in a solution of hydrofluoric acid, boiled three times for 1 hour in distilled water, dried for 20 hours at 120 ° C, poured into a cell with a diameter of 18 mm, a height of 15 mm with a graphite heater or a cell with a diameter of 30 mm, a height of 7 m (with a metal heater), create a pressure of 8.5 GPa, heated to 1800 ° C withstand 100 s (or 1000 s). A diamond compact is obtained with a diameter of 16 mm, a height of 12 mm (or a diameter of 28 mm, a height of 5 mm), a resistance of more than 10 Ohm cm (or 10 Ohm cm), an ash content of less than 0.01 wt.%, A strength of 6.5 GPa (or 4 , 0 GPa), thermal strength - unchanged up to 1200 ° C, thermal conductivity -600 W / (m deg) (or 450 W / (m deg)).

. Elements of a given shape and size, for example, triangular prisms, cubes, parallelepipeds, cylinders, needles, are cut from polycrystalline diamond billets using a laser and embedded into the ceramic-metal matrix of a drilling tool by heating without oxygen to 1150 ° C. Cutting fractions to obtain a grinding powder with a grain size of up to 2.5 mm, which is used in impregnated crowns, single-layer crowns, diamond saws and other tools. In addition, compacts are used for the manufacture of dies (die) or the manufacture of substrates for electronic components where high thermal conductivity, electrical resistance, low loss at high frequencies, etc. are required.

The above method can be used to obtain compacts with increased heat resistance from diamonds synthesized from graphite using metal catalysts. However, in this

In this case, it is possible to remove only a part of inclusions from the surface region of grains and from open pores. The presence of metals and carbides with sizes of 10–100 nm in closed pores softens the polycrystal at

heating up. The degree of softening depends on the number of inclusions and varies from 0.3 o to 0.7 o (o - initial strength) if heated to 1200 ° C for 30 minutes, if the content of inclusions varies from 0.2 to 2 wt. .%. If the content of inclusions is 2-5 wt%, then complete softening occurs at 1200 ° C, and at 1000 ° C the degree of softening is respectively E (0.7-0.3) g.

The proposed method allows to obtain polycrystalline diamonds with high abrasion resistance. Compared with single crystals, these characteristics are higher by an average of 20%. Strength

crushing pressure is 4.0-6.5 GPa. Heating to 1200 ° C (in the absence of oxygen) does not lead to a decrease in the initial strength. These polycrystalline diamonds can replace, in their physicochemical parameters, natural single crystals of diamond of groups XV and XXXV used in drilling equipment.

For compacting, isometric granules of all sizes from 1 to

100 microns, which are divided into narrow fractions from 10/1 microns to 100/90 microns. In these examples, fractions of 20 / 10.30 / 20 and 100/80 microns were taken. These fractions are compacted by this method more successfully with optimal strength characteristics.

Comparative analysis of diamonds obtained by the prototype, in comparison with

the proposed method shows that diamond compacts per vitell (AKPM-1, AKPK-1, AKSB-1) and single crystals of natural diamonds have the same heat resistance to. while diamond compacts obtained by recrystallization in a metal melt (AKSK-1, AKSM-1) have a reduced thermal strength at T ° 1200 ° C, which is 10-30% of the initial value, which does not allow their use temperatures and above. In addition, the proposed method allows to obtain polycrystalline diamonds with increased strength and abrasion resistance. Compared with single crystals, these characteristics are higher by an average of 20%. The crushing strength is 4.0-6.5 GPa. Compacted polycrystalline diamonds can replace, in their physicochemical parameters, natural single crystals of diamond of groups XV and XXXV used in drilling equipment. Preforms for the manufacture of articles of various shapes can be made from them.

Claims (1)

SUMMARY OF THE INVENTION A method for producing polycrystalline diamonds, comprising exposing a carbon material to high pressure when heated in the region of thermodynamic stability of a diamond, characterized in that, in order to increase the strength and thermal strength of polycrystalline diamonds by activating the surface of the starting diamond material and optimizing the properties of the crystals, as carbon The material is used diamond, which is pre-crushed to obtain isometric granules with a size of 1-100 microns, section fractions and subjected to purification from impurities with solutions of acids: boiling perchloric (30-70%) for 10-20 hours, a mixture of salt (density 1.19 g / cm), nitrogen (density 1.40 g / cm and distilled water in a ratio of 1: 1: 1 by volume for 2-4 hours, hydrofluoric (40%) for 1-2 hours, then washed with distilled boiling water with a three-time replacement for 0.5-1 hours and dried for 10-20 hours at 100-120 ° C.