Method for preparing diamond-cemented carbide compact by high temperature and high pressure sintering

Abstract

The present application relates to a preparation method of diamond-cemented carbide composite sheet high-temperature and high-pressure sintering, which comprises the following steps: loading the purified cemented carbide base and diamond micro-powder into a metal cup, buckling the cover cup, loading the synthesis block, and placing the synthesis block into a six-surface press for high-temperature and high-pressure sintering; the press is raised to 35-60 MPa, and the six top hammers of the six-surface press synchronously extrude the sintering cavity to the geometric center of the press to form high-pressure sealing; under the high-pressure extrusion, the gas stored in the carbon aerogel conductive sheet in the high-pressure cavity is released, the current is passed, the carbon tube is heated to 550-750 DEG C in the high-pressure cavity, and maintained for 5-10 min; the hydrogen gas in the high-pressure cavity generates a reduction reaction under high temperature to remove the impurities adhered to the surface of the diamond particles and purify the environment in the high-pressure cavity; then the pressure is raised to 6-8 GPa, the temperature is raised to 1450-1500 DEG C, and maintained for 8-15 min, so that firm bond is formed between the diamond particles to improve the sintering yield.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of diamond hard alloy composite sheet high temperature high pressure sintering preparation method, belong to diamond hard alloy composite sheet manufacturing technical field. BACKGROUND

[0002] Diamond hard alloy composite sheet is sintered from diamond micro powder and hard alloy pedestal under high temperature and high pressure, with high hardness, high wear resistance of diamond and impact resistance of hard alloy, for manufacturing diamond drill bit, finally for exploration and exploitation of oil, natural gas, shale gas.

[0003] Currently, when diamond hard alloy composite sheet is manufactured, salt piece and salt tube are melted at 1450 DEG C, 6GPa high temperature and high pressure, and metal cup is wrapped by changing from solid phase to liquid phase;Commonly used diamond particles have average particle size of 35um, 20um and 10um, because these diamond powder materials have large specific surface area, a large amount of oxygen and other gases are adsorbed, these pollutants affect sintering between diamond particles, so that there are cracks, pits, vertical cracks of outer circle, cover falling and other defects in sintered diamond layer, the sum of these defects is about 30% of all sintered products, and the qualified rate of final product is only 70%. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art, and provide a kind of diamond hard alloy composite sheet high temperature high pressure sintering preparation method.

[0005] The purpose of the present application is realized by the following technical scheme:

[0006] The preparation method of diamond hard alloy composite sheet high temperature high pressure sintering, characterized by: the device for preparing diamond hard alloy composite sheet comprises talc, salt tube and carbon tube, talc has through hole for assembling carbon tube and conductive steel ring, carbon tube is assembled in it, salt tube is assembled in carbon tube, metal cup containing hard alloy pedestal and diamond micro powder is put into salt tube, upper and lower ports are packaged with salt piece, carbon aerogel conductive sheet and conductive steel ring are assembled in the through hole of talc at upper and lower ends, and carbon aerogel conductive sheet is attached to carbon tube, salt tube and salt piece;Carbon aerogel conductive sheet is sponge structure, and sponge structure is used to store gas;

[0007] Purified hard alloy pedestal and diamond micro powder are assembled in metal cup, cover cup is buckled, synthesis block is assembled, synthesis block is placed in six-surface press for high temperature and high pressure sintering;

[0008] The press is slowly boosted to 35-60 MPa, and six top hammers of the six-sides top press synchronously extrude the sintering cavity to the geometric center of the press, and meanwhile, high pressure sealing is formed; under the extrusion of high pressure, the gas stored in the carbon aerogel conductive sheet in the high pressure cavity is released, current is passed, the carbon tube is heated to 550-750 DEG C in the high pressure cavity, and maintained for 5-10 min, and under high temperature, hydrogen in the high pressure cavity generates reduction reaction to remove the impurities attached to the surface of the diamond particles, and purify the environment in the high pressure cavity;

[0009] Continue to boost to 6-8 GPa, and meanwhile, temperature is raised to 1450-1500 DEG C, and maintained for 8-15 min, so that firm bond is formed between the diamond particles, and sintering of the diamond composite sheet is completed.

[0010] Further, in the above-mentioned preparation method of the diamond-cemented carbide composite sheet high-temperature high-pressure sintering, the carbon aerogel conductive sheet has an electric conductivity of 25-100 S / cm.

[0011] Further, in the above-mentioned preparation method of the diamond-cemented carbide composite sheet high-temperature high-pressure sintering, the carbon aerogel conductive sheet has a sponge structure with a specific surface area of 400-1000 m 2 / g, porosity of 80%-98.5%, and thickness of 0.05-2 mm.

[0012] Further, in the above-mentioned preparation method of the diamond-cemented carbide composite sheet high-temperature high-pressure sintering, the carbon aerogel conductive sheet has a sponge structure storing hydrogen or inert gas or mixed gas of hydrogen and inert gas.

[0013] Further, in the above-mentioned preparation method of the diamond-cemented carbide composite sheet high-temperature high-pressure sintering, the sponge structure stores mixed gas of hydrogen and nitrogen, wherein the hydrogen accounts for 5%, and the nitrogen accounts for 95%.

[0014] Further, in the above-mentioned preparation method of the diamond-cemented carbide composite sheet high-temperature high-pressure sintering, the purity of the hydrogen is 99.9%.

[0015] Compared with the prior art, the present application has obvious advantages and beneficial effects, which are embodied in the following aspects.

[0016] The sintering cavity can self-clean the internal environment during the high-temperature high-pressure working stage, the sintering cavity is introduced with oxidation-reduction reaction, the oxidation-reduction reaction of hydrogen under high temperature is used to remove impurities and purify the environment in the high pressure cavity, so that the diamond sintering process is smoothly performed, the negative influence of gas impurities during high-temperature high-pressure sintering is removed, and the sintering yield is improved.

[0017] The functional component (carbon aerogel conductive sheet) in the high-temperature high-pressure cavity is made of the structure material with hydrogen storage function, so that the structure material has both functions.

[0018] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. The objects and other advantages of the application can be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0020] Figure 1 Figure 1 is a structural schematic diagram of the process device of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art without creative labor on the basis of the embodiments of the present application belong to the scope of protection of the present application.

[0022] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. Meanwhile, in the description of the present application, orientation terms and order terms, etc. are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0023] As shown in Figure 1, the device for preparing diamond-cemented carbide composite sheet comprises a pyrophyllite 1, a salt tube 6 and a carbon tube 5, the pyrophyllite 1 has a through hole for fitting the carbon tube 5 and a conductive steel ring 2, the carbon tube 5 is fitted in the through hole, the salt tube 6 is fitted in the carbon tube 5, a metal cup 7 containing a cemented carbide base and diamond micro powder is put into the salt tube 6, the upper and lower ports are sealed with salt sheets 4, the conductive steel ring 2 and the carbon aerogel conductive sheet 3 are fitted in the through hole of the pyrophyllite 1, and the carbon aerogel conductive sheet 3 is in contact with the carbon tube 5, the salt tube 6 and the salt sheets 4; the carbon aerogel conductive sheet 3 has a sponge-like structure for storing gas. Figure 1 The sponge-like structure is used to store gas.

[0024] The graphene aerogel (foam) or carbon nanotube sponge is processed into a cylindrical sheet as the carbon aerogel conductive sheet 3, which has a three-dimensional network structure and can store gas in the pores.

[0025] The sintering cavity heating current is introduced from the upper and lower top hammers of the press, transmitted to the carbon aerogel conductive sheet 3 through the conductive steel ring, and then transmitted to the carbon tube 5 to generate heat, thereby providing heat for the entire high-temperature and high-pressure cavity. The carbon aerogel conductive sheet 3 has good electrical conductivity, with an electrical conductivity coefficient of 25-100 S / cm; the specific surface area of the sponge-like structure of the carbon aerogel conductive sheet is 400-1000 m 2 / g, and the porosity is 80%-98.5%, which can be self-supporting and has a certain toughness. The carbon aerogel conductive sheet is formed into a sheet and used as a conductive sheet, with a thickness of 0.05-2 mm; the sponge-like structure stores hydrogen or inert gas or a mixture of hydrogen and inert gas, and the mixture of hydrogen and nitrogen is preferred, in which the hydrogen content is 5% and the nitrogen content is 95%, and the purity of hydrogen is 99.9%.

[0026] In the specific preparation, the diamond powder is first subjected to acid and alkali purification treatment, and the impurities on the surface of the cemented carbide base are removed by sandblasting. The purified cemented carbide base and the diamond powder are loaded into a metal cup, and the metal cup loaded with the cemented carbide base and the diamond powder is placed in a vacuum furnace for high-temperature purification treatment. The metal cup after purification is buckled with a cover cup, and a synthetic block is loaded into the cover cup. The synthetic block is placed in a six-sided press for high-temperature and high-pressure sintering.

[0027] The press is slowly pressurized to 35-60 MPa, and the six top hammers of the six-sided press are synchronously extruded to the geometric center of the press to form a high-pressure seal. Under the extrusion of high pressure, the gas stored in the carbon aerogel conductive sheet in the high-pressure cavity is released, and the current is passed to heat the carbon tube to 550-750℃ in the high-pressure cavity, which is maintained for 5-10 min. The hydrogen in the high-pressure cavity produces a reduction reaction at high temperature to remove the impurities attached to the surface of the diamond particles and purify the environment in the high-pressure cavity.

[0028] The pressure is continuously increased to 6-8 GPa, and the temperature is simultaneously increased to 1450-1500℃, which is maintained for 8-15 min to form a firm bond between the diamond particles and complete the sintering of the diamond composite sheet.

[0029] The sintered diamond composite sheet blank has a dense and complete diamond layer, except for slight undulations on the macro surface, and the final product yield reaches 88-94%.

[0030] Comparative Example

[0031] The diamond-cemented carbide composite sheet is prepared by using the existing high-temperature and high-pressure sintering technology. Specifically, the average size of the diamond powder is 30 um, and the average specific surface area is 0.4025 m2 / g. After the diamond powder and the cemented carbide substrate are treated and assembled, and vacuum purification, the sintering is performed at 1450 °C and 6.0 GPa for 6.5 min. Finally, the equipment is depressurized to normal pressure, and the temperature is reduced to room temperature to obtain the diamond-cemented carbide composite sheet blank. After the blank is mechanically ground, the proportion of the cracked, edge-fallen and cover-fallen products is about 20% to 30%, the proportion of the cover-fallen products is about 5% to 10%, and finally the yield of the finished product is about 70% to 75%.

[0032] Example 1

[0033] The device shown in Figure 1 is used, and a carbon aerogel conductive sheet 3 with a specific gravity of 0.30 g / cm 3 is used. The voids of the aerogel are filled with a mixed gas of hydrogen and nitrogen, in which the hydrogen is 5%, and the nitrogen is 95%. The average size of the diamond powder is 20 um, and the average specific surface area is 0.6884 m 2 / g.

[0034] The high-pressure heating process is used. First, the press is slowly pressurized to 40 MPa, and the six top hammers of the six-sides press are synchronously extruded to the geometric center of the press to form a high-pressure seal. Under the extrusion of high pressure, the mixture of hydrogen and nitrogen stored in the carbon aerogel conductive sheet in the high-pressure cavity is released. The carbon tube is heated to 600 °C in the high-pressure cavity by passing current, and maintained for 7 min. The hydrogen in the high-pressure cavity generates a reduction reaction at high temperature to remove the gas impurities attached to the surface of the diamond particles, and purifies the environment in the high-pressure cavity. At this time, the nitrogen acts as an inert gas to maintain the high-pressure environment in the high-pressure cavity, and has no negative effect on the whole high-pressure sintering process. The pressure is continuously increased to 6-8 GPa, and the temperature is simultaneously increased to 1450-1500 °C, and maintained for 7 min to form a firm bond between the diamond particles. Finally, the sintering process of the diamond composite sheet is completed. The diamond-cemented carbide composite sheet blank is obtained. After the blank is mechanically ground, the proportion of the defective products is significantly reduced, the proportion of the cover-fallen products is 0%, and the degree of the cracks, edge-fallen, pits and vertical columns and the proportion of the defects are reduced by about 7%. The yield of the finished product is increased to 89%.

[0035] Example 2

[0036] The device shown in Figure 1 is used, and a carbon aerogel conductive sheet 3 with a specific gravity of 0.40 g / cm 3 is used. The voids of the aerogel are filled with hydrogen with a purity of 99.9%. The average size of the diamond powder is 10 um, and the average specific surface area is 0.8767 m 2 / g.

[0037] The high-pressure heating process is adopted, the press is slowly raised to 55MPa first, six top hammers of the six-sides top press are extruded to the geometric center of the press synchronously, and high-pressure sealing is formed at the same time; under the extrusion of high pressure, hydrogen stored in the carbon aerogel conductive sheet in the high-pressure cavity is released; the current is passed, the carbon tube is heated to 720 DEG C in the high-pressure cavity, and maintained for 10min, the hydrogen in the high-pressure cavity generates strong reduction reaction under high temperature, removes the gas impurities attached to the surface of the diamond particles, and purifies the environment in the high-pressure cavity; the pressure is continuously raised to 6-8GPa, and the temperature is simultaneously raised to 1480-1500 DEG C, and maintained for 8min, so that firm bond is formed between the diamond particles, and the sintering process of the diamond composite sheet is finally completed, and the diamond-cemented carbide composite sheet blank is obtained. After the blank is mechanically ground, the proportion of defective products is reduced, the proportion of cover falling is 0%, the degree of defects such as cracks, edge falling, pits and vertical columns is small, and the proportion is reduced by about 3%; the yield is improved to 92%.

[0038] In conclusion, the method can clean the internal environment of the sintering cavity during the high-temperature and high-pressure working stage, introduce the oxidation-reduction reaction in the sintering cavity, remove impurities by using the oxidation-reduction reaction of hydrogen at high temperature, purify the environment in the high-pressure cavity, make the diamond sintering process smooth, remove the negative influence of gas impurities during high-temperature and high-pressure sintering, and improve the sintering yield.

[0039] The structural material with the hydrogen storage function is used to manufacture the functional component (carbon aerogel conductive sheet) in the high-temperature and high-pressure cavity, so that the functional component has the hydrogen storage function.

[0040] The above merely describes the preferred embodiments of the present application and is not used to limit the present application, and various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0041] The above merely describes the preferred embodiments of the present application and is not used to limit the present application, and various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0042] It is to be noted that, as used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" can include a combination of two or more components. Similarly, the terms "one" and "the" do not exclude the presence of more than one item, unless the context clearly indicates otherwise. Further, the terminology "an" and "one" are used in the detailed description and claims only to mean one or more, at least one, or "at least one." Finally, the words "comprise," "comprises," and "comprising" and the like, are to be construed in their broadest, intended, and open ended form to encompass events that would otherwise prevent a process, method, article, or apparatus from being encompassed by the claim.

Claims

1. A method for preparing a diamond-cemented carbide compact by high temperature and high pressure sintering, characterized in that: The device for preparing the diamond-cemented carbide composite sheet comprises a pyrophyllite, a salt tube and a carbon tube, the pyrophyllite has a through hole for fitting the carbon tube and a conductive steel ring, the carbon tube is fitted in the through hole, the salt tube is fitted in the carbon tube, a metal cup containing a cemented carbide base and diamond powder is put in the salt tube, the upper and lower ends of the through hole of the pyrophyllite are fitted with carbon aerogel conductive sheets and the conductive steel ring, the carbon aerogel conductive sheets are in contact with the carbon tube, the salt tube and the salt sheets, the carbon aerogel conductive sheets have a sponge structure, and the sponge structure stores hydrogen gas or a mixture of hydrogen gas and inert gas. The purified cemented carbide base and diamond powder are put in the metal cup, the cover cup is buckled, the synthesis block is loaded, and the synthesis block is put in a cubic press for high-temperature and high-pressure sintering. The press is slowly pressurized to 35-60 MPa, six top hammers of the cubic press synchronously extrude the sintering cavity to the geometric center of the press, and high-pressure sealing is formed at the same time; under the extrusion of high pressure, the gas stored in the carbon aerogel conductive sheets in the high-pressure cavity is released, current is passed, the carbon tube is heated to 550-750 ℃ in the high-pressure cavity, and the temperature is maintained for 5-10 min; the hydrogen gas in the high-pressure cavity generates a reduction reaction at high temperature to remove impurities attached to the surface of the diamond particles, and the environment in the high-pressure cavity is purified. The pressure is continuously increased to 6-8 GPa, and the temperature is simultaneously increased to 1450-1500 ℃, and maintained for 8-15 min, so that firm bond is formed between the diamond particles, and the sintering of the diamond composite sheet is completed.

2. The method of claim 1, wherein the method further comprises: The carbon aerogel conductive sheet has a conductive coefficient of 25-100 S / cm. ​ 3. The method of claim 1, wherein the method further comprises: Sponge-like structure of carbon aerogel conductive sheet has specific surface area of 400-1000 m 2 / g, porosity of 80%-98.5%, and thickness of 0.05-2 mm. ​ 4. The method of claim 1, wherein the method further comprises: The sponge structure stores a mixture of hydrogen gas and nitrogen gas, wherein the hydrogen gas accounts for 5%, and the nitrogen gas accounts for 95%. ​ 5. The method of claim 4, wherein the method further comprises: The purity of the hydrogen gas is 99.9%. ​

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