High-purity diamond compact and method for manufacturing the same

Abstract

The present application provides a high-purity diamond compact, which comprises diamond micro-powder and a cemented carbide substrate, and the diamond micro-powder is pretreated by a ball-free mixing method. The diamond micro-powder is uniformly mixed by the ball-free mixing method, and since no grinding ball of other materials such as cemented carbide is used, the micro-powder pollution caused by the collision and friction between the balls and between the balls and the tank is effectively improved, thereby reducing the introduction of impurities in the diamond micro-powder during the mixing process and greatly reducing the influence of the impurities on the performance of the diamond compact. In addition, the present application also provides a preparation method of the high-purity diamond compact, which comprises the following steps: uniformly mixing the diamond micro-powder by the ball-free mixing method; removing impurities from the uniformly mixed diamond micro-powder; and compounding the impurity-removed diamond micro-powder with the cemented carbide substrate to obtain the high-purity diamond compact.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diamond compact, in particular to a high-purity diamond compact and a preparation method thereof. BACKGROUND

[0002] As diamond has extremely high hardness and wear resistance, its broken micro powder is widely used in various grinding and polishing fields. Among them, micron-level diamond micro powder is mainly used to manufacture diamond cutting and grinding tools and components. Diamond compact, as a key part of oil drilling bits, directly determines the drilling efficiency of the bit.

[0003] The diamond compact is composed of a PCD (Polycrystalline diamond) cutting part and a hard alloy substrate support part, wherein the PCD layer is formed by sintering diamond micro powder under high temperature and high pressure. The performance of the diamond compact is closely related to the quality of the diamond micro powder itself, including its strength, morphology, particle size composition, purity and the like. Among them, the strength and morphology of the diamond micro powder are determined by the diamond raw material and its crushing process, the particle size composition of the diamond micro powder can affect the wear resistance and impact resistance of the diamond compact by adjusting the micro powder ratio, and the purity of the diamond micro powder is often difficult to effectively control due to the mixing of impurities in the production process of the diamond compact.

[0004] In order to fully mix the well-proportioned diamond mixed micro powder, a mixing method with hard alloy or ceramic grinding balls is usually used. In the process of ball milling and mixing, the friction and collision between the grinding balls and the tank will not only cause the powder to be broken and the particle size to be refined, but also cause pollution due to the wear of the grinding balls, which is often the main source of impurities in the micro powder. Generally speaking, the impurity content in the raw powder is 100-200 ppm, the impurity content in the mixed powder after ball milling is more than 1000 ppm, and the impurity content increases with the increase of the rotation speed and time of ball milling. In addition, impurities in the air can also be absorbed during the weighing and assembling process, and the original micro powder raw material itself may have a small amount of impurities, which will all lead to a decrease in the performance of the sintered diamond compact.

[0005] The fine powder impurities usually contain Fe, Al, Ni, Si and other metal and non-metal substances, and the fine powder manufacturers usually use acid boiling method to remove impurities from the fine powder, for example, the related art discloses a method of boiling the diamond fine powder with strong acid to dissolve the impurities, but this method is mainly aimed at the impurities with high content introduced in the production process of the fine powder due to sintering and crushing, and the acid boiling method is mainly aimed at a large amount of fine powder. However, since the diamond fine powder raw material for the diamond composite sheet has undergone a purification process before leaving the factory, the impurity content is usually low, and the diamond fine powder used for the diamond composite sheet is in small amount, therefore, the purification of the diamond fine powder used for the diamond composite sheet is not suitable for the acid boiling method. In addition, the acid boiling method also has problems of large acid / alkali consumption, low production efficiency, serious pollution, etc., and the acid solution itself can also introduce trace impurities.

[0006] In addition to the acid boiling method, the existing technology also has an electrolytic impurity removal method, which is suitable for large-scale production with high metal impurity content and large production batch, but for the mechanically crushed diamond fine powder, the proportion of impurity components is usually less than 3%, which is not suitable for the electrolytic purification process.

[0007] Therefore, in order to reduce the influence of the purity of the diamond fine powder on the performance of the diamond composite sheet, it is urgent to find a new diamond composite sheet and a preparation method thereof. SUMMARY

[0008] In view of the defects in the prior art, the technical problem solved by the present application is to provide a high-purity diamond composite sheet and a preparation method thereof, which can effectively reduce the impurity content in the diamond fine powder and greatly reduce the influence of impurities on the performance of the diamond composite sheet.

[0009] To achieve the above object, in a first aspect, the present application provides a high-purity diamond composite sheet, comprising diamond fine powder and cemented carbide matrix, wherein the diamond fine powder is pretreated by a ball-free mixing method.

[0010] Preferably, the ball-free mixing method specifically comprises the following steps: mixing different particle sizes of diamond fine powder in a mixing tank, wherein the different particle sizes of diamond fine powder, calculated by mass percentage, comprise: 63% to 67% of diamond fine powder with a particle size of 30 to 40 microns, 18% to 22% of diamond fine powder with a particle size of 10 to 15 microns, 11% to 15% of diamond fine powder with a particle size of 4 to 8 microns, and 1% to 3% of diamond fine powder with a particle size of 1 to 2 microns.

[0011] Preferably, the ball-free mixing method uses ordinary ball-free mixing technology or acoustic resonance ball-free mixing technology.

[0012] Preferably, the diamond powder is pretreated by the ball-free mixing method, and then the uniformly mixed diamond powder is further purified by the acid mist distillation method.

[0013] Preferably, the acid mist distillation method comprises the following steps: placing the uniformly mixed diamond powder on a porous baffle in a purification bottle, the purification bottle being in communication with an acid distillation bottle for generating acid mist to purify the diamond powder.

[0014] Preferably, the purification bottle is also in communication with a high-purity water distillation bottle for generating water vapor to elute soluble impurities and residual acid from the diamond powder.

[0015] Preferably, the flow rate of the acid mist and the water vapor is 30-50 mL / min per 100 g of the mixed diamond powder.

[0016] Preferably, the acid distillation bottle contains an acid selected from at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0017] Preferably, the diamond powder is provided with polytetrafluoroethylene films on the top and bottom surfaces thereof for filtering the acid mist.

[0018] In a second aspect, the present application also provides a method for preparing a high-purity diamond composite sheet, comprising the following steps:

[0019] mixing the diamond powder uniformly by the ball-free mixing method;

[0020] purifying the uniformly mixed diamond powder;

[0021] mixing the purified diamond powder with a cemented carbide substrate to obtain a high-purity diamond composite sheet.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] (1) In the process of preparing the diamond composite sheet, the diamond powder is mixed uniformly by the ball-free mixing method, which effectively reduces the contamination of the diamond powder caused by the collision and friction between the balls and between the balls and the tank, thereby reducing the introduction of impurities in the mixing process of the diamond powder and greatly reducing the influence of the impurities on the performance of the diamond composite sheet. At the same time, the ball-free mixing can also avoid the breakage of coarse particles caused by the collision of the balls, so that the particle size distribution is changed, thereby affecting the performance of the diamond composite sheet.

[0024] (2) In the process of preparing diamond composite sheets, the present invention uses acid mist distillation to remove impurities from diamond micro powder. The acid mist distillation method can remove impurities in the micro powder to a large extent. Moreover, the acid vapor generated by acid mist distillation can avoid the introduction of impurities in the acid solution. Compared with acid boiling or electrolysis, it is more suitable for the further high-purity purification of a small amount of diamond micro powder for diamond composite sheets. It greatly reduces the impact of impurities in diamond micro powder on the performance of diamond composite sheets. In addition, the acid mist distillation method can reduce acid consumption, resulting in high production efficiency and less pollution. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the acid mist distillation device in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the micro-powder filtration section in the acid mist distillation device according to an embodiment of the present invention;

[0028] Figure 3 This is a particle size analysis of the mixed diamond micron powder in an embodiment of the present invention.

[0029] In the diagram: 1-Acid distillation flask, 2-High-purity water distillation flask, 3-Acid heater, 4-Acid mist flow valve, 5-Conduit, 6-Purification bottle, 7-Micro powder filter section, 8-Condensed acid, 9-Acid outlet, 10-Water vapor flow valve, 11-High-purity water heater, 71-Upper PTFE membrane, 72-Diamond micro powder, 73-Lower PTFE membrane, 74-Porous partition. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The embodiment of the present application provides a high-purity diamond compact and a preparation method thereof, wherein the diamond powder is uniformly mixed by a ball-free mixing method, the introduction of impurities in the mixing process of the diamond powder is greatly reduced, the impurity content in the diamond powder is effectively reduced, the influence of impurities on the performance of the diamond compact is greatly reduced, and the technical problem of high impurity content and great influence on the performance of the diamond compact caused by the mixing method with the hard alloy or ceramic grinding ball in the prior art is solved.

[0032] To achieve the above technical effects, the general idea of the present application is as follows:

[0033] In one aspect, the present application provides a high-purity diamond compact, comprising diamond powder and a hard alloy substrate, wherein the diamond powder is pretreated by a ball-free mixing method.

[0034] The present application uniformly mixes the diamond powder by a ball-free mixing method, greatly reduces the introduction of impurities in the mixing process of the diamond powder, effectively reduces the impurity content in the diamond powder, greatly reduces the influence of impurities on the performance of the diamond compact, and solves the technical problem of high impurity content and great influence on the performance of the diamond compact caused by the mixing method with the hard alloy or ceramic grinding ball in the prior art.

[0035] Preferably, the ball-free mixing method specifically comprises the following steps: the diamond powder with different particle sizes is loaded into a mixing tank and uniformly mixed, wherein the diamond powder with different particle sizes comprises, by mass percentage, 63-67% of diamond powder with a particle size of 30-40 mu m, 18-22% of diamond powder with a particle size of 10-15 mu m, 11-15% of diamond powder with a particle size of 4-8 mu m, and 1-3% of diamond powder with a particle size of 1-2 mu m.

[0036] Preferably, the ball-free mixing can adopt ordinary ball-free mixing technology or acoustic resonance ball-free mixing technology.

[0037] When the ordinary ball-free mixing technology is adopted, the loading amount of the diamond powder is 1 / 4-1 / 3 of the volume of the mixing tank, the mixing rotation speed is 80-240 rpm, and the mixing time is greater than or equal to 4 hours.

[0038] When the acoustic resonance ball-free mixing technology is adopted, the loading amount is 1 / 4-1 / 3 of the volume of the mixing tank, the mixing acceleration is 50-60 g, the mixing frequency is 60-70 Hz, and the mixing time is 15-18 minutes. The above acoustic resonance ball-free mixing technology is based on the resonance generated by the driving system and the spring system to realize the vertical vibration of the container with low frequency and large acceleration under the condition of small input energy, to generate macroscopic vibration dispersion and microscopic acoustic flow dispersion coupling effect in the mixed material, and to have higher mixing efficiency.

[0039] The mixing tank is made of stainless steel or other materials.

[0040] Preferably, the mixed diamond powder is subjected to particle size analysis to determine the uniformity of the mixing.

[0041] Tests have proved that the particle size formula and the ball-free mixing process can not only reduce the introduction of impurities in the mixing process, but also achieve good mixing uniformity.

[0042] Preferably, the mixed diamond powder is subjected to particle size analysis to determine the uniformity of the mixing.

[0043] Preferably, the mixed diamond powder is subjected to particle size analysis to determine the uniformity of the mixing.

[0044] The acid mist distillation method can remove impurities in the diamond powder to a great extent, and the acid mist produced by the acid mist distillation method can avoid the introduction of impurities in the acid solution. Compared with the existing acid boiling method or electrolysis method, the acid mist distillation method is more suitable for further high-purity purification of a small amount of diamond powder for diamond composite sheets, and greatly reduces the influence of impurities in the diamond powder on the performance of the diamond composite sheet.

[0045] Preferably, the acid mist distillation method comprises the following steps: placing the mixed diamond powder on a porous partition in a purification bottle, the purification bottle being in communication with an acid liquid distillation bottle, and the acid liquid distillation bottle being used to generate acid mist for removing impurities from the diamond powder. The acid mist generated by the acid liquid distillation bottle flows through the diamond powder in the purification bottle, and can fully contact and react with the impurities in the diamond powder. This not only improves the impurity removal efficiency, but also reduces the amount of acid loss and environmental pollution, and does not introduce impurities in the acid liquid into the diamond powder.

[0046] Preferably, the purification bottle is also in communication with a high-purity water distillation bottle, and the high-purity water distillation bottle is used to generate water vapor to elute the residual soluble impurities and acid liquid in the diamond powder. The present application also provides a high-purity water distillation bottle, which can generate water vapor. After the acid reacts with the impurities, the water vapor can be used to elute the residual soluble impurities and acid liquid in the diamond, further improving the purity of the diamond powder.

[0047] Preferably, the acid liquid distillation flask and the high-purity water distillation flask are each provided with a heating device for heating the acid liquid distillation flask and the high-purity water distillation flask to obtain acid mist and water vapor; and a flow valve is arranged at the outlet of the acid liquid distillation flask and the high-purity water distillation flask, and the flow valve is used to control the flow of the acid mist and the water vapor.

[0048] Preferably, the acid mist distillation method uses 30-50 mL / min of acid mist and water vapor per 100 g of mixed powder to ensure that the acid mist can fully contact and react with the impurities in the diamond micro-powder, and the water vapor can fully dissolve the residual impurities and the acid liquid, thereby further improving the purity of the diamond micro-powder.

[0049] Preferably, the acid liquid distillation time is 30-60 min, and the water vapor washing time is more than 10 min, until the solution at the outlet is neutral as detected by pH test paper.

[0050] Preferably, after the solution at the outlet is neutral as detected by pH test paper, the diamond micro-powder is subjected to drying treatment.

[0051] Preferably, the acid liquid distillation flask contains an acid liquid, and the acid liquid is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid, wherein the hydrochloric acid, the nitric acid and the sulfuric acid are all of analytical purity and concentration.

[0052] Preferably, the acid liquid is a mixture of hydrochloric acid and nitric acid, and when the acid liquid is a mixture of hydrochloric acid and nitric acid, the volume ratio of the hydrochloric acid to the nitric acid is 1:(3-4).

[0053] Preferably, the volume ratio of the hydrochloric acid to the nitric acid is 1:3. Tests show that when the analytical pure hydrochloric acid and the analytical pure nitric acid are mixed in a volume ratio of 1:3, the solubility of the impurities in the diamond micro-powder is better.

[0054] Preferably, the diamond micro-powder is located at the middle part of the purification flask, the purification flask is divided into an upper space and a lower space, the upper space is in communication with the acid liquid distillation flask and the high-purity water distillation flask, the lower space is an acid liquid condensation and collection space, and the bottom of the lower space (i.e. the bottom of the purification flask) is provided with an acid liquid outlet. The acid mist flows from top to bottom through the diamond micro-powder, reacts with the impurities in the diamond micro-powder, and then condenses in the acid liquid condensation and collection space and flows out through the acid liquid outlet; when the water vapor is washed, the water vapor flows from top to bottom through the diamond micro-powder, dissolves the soluble impurities and the residual acid mist in the diamond micro-powder after reaction, and then condenses in the acid liquid condensation and collection space and flows out through the acid liquid outlet.

[0055] Preferably, during the acid mist distillation process, the diamond powder is provided with polytetrafluoroethylene film both above and below (i.e. a layer of polytetrafluoroethylene film is laid on the porous partition plate before the diamond powder is laid on the porous partition plate, which is the lower polytetrafluoroethylene film, and a layer of polytetrafluoroethylene film is laid on the diamond powder after the diamond powder is laid on the porous partition plate, which is the upper polytetrafluoroethylene film), the polytetrafluoroethylene film is used to filter the acid mist, and the upper polytetrafluoroethylene film can also disperse the airflow to make the acid vapor uniformly permeate the powder; the lower polytetrafluoroethylene film also plays the role of bearing the powder, filtering the acid mist and condensing the acid liquid.

[0056] Preferably, the pore size of the upper polytetrafluoroethylene film is set to 0.4-0.8 μm, the pore size of the lower polytetrafluoroethylene film is set to 0.1-0.3 μm, and the thickness of the powder layer is set to ≤1.5 cm.

[0057] Since the upper and lower polytetrafluoroethylene films play the role of isolation and bearing, they can make the acid mist effectively pass through the diamond powder, and also can avoid the leakage of fine powder, therefore, the pore size of the upper polytetrafluoroethylene film is set to be slightly larger, i.e. 0.4-0.8 μm, which is beneficial to the entry of the acid mist into the powder layer; the pore size of the lower polytetrafluoroethylene film is set to be slightly smaller, i.e. 0.1-0.3 μm, which can avoid the leakage of the powder. In addition, the thickness of the powder layer should not be too large, otherwise the acid mist cannot fully clean the powder, which affects the purification effect.

[0058] Preferably, before the acid mist distillation of the diamond powder, the method further comprises a hydrogen burning treatment step of the diamond powder, which is specifically that hydrogen is introduced into the mixed diamond powder and heated. The purpose of the hydrogen burning treatment is to reduce the oxides in the mixed diamond powder into metals, decompose organic impurities, reduce the impurity content in the diamond powder, and improve the purification efficiency of the acid mist distillation.

[0059] Preferably, the temperature of the hydrogen burning treatment is 650-820 ℃, the treatment time is 2-4 h, and the hydrogen flow rate used for every 100 g of mixed powder is 50-200 mL / min.

[0060] On the other hand, the application also provides a preparation method of high-purity diamond composite sheet, which comprises the following steps:

[0061] The diamond powder is mixed uniformly by a ball-free mixing method;

[0062] The mixed diamond powder is purified;

[0063] The purified diamond powder is combined with a cemented carbide substrate to obtain a high-purity diamond composite sheet.

[0064] The present application adopts the method of ball-free mixing to mix the diamond micro-powder uniformly, greatly reduces the introduction of impurities in the mixing process of the diamond micro-powder, effectively reduces the impurity content in the diamond micro-powder, greatly reduces the influence of impurities on the performance of the diamond composite sheet, and solves the technical problems of high impurity content and great influence on the performance of the diamond composite sheet caused by the mixing method with hard alloy or ceramic grinding balls in the prior art.

[0065] Preferably, the ball-free mixing method specifically comprises the following steps: the diamond micro-powder with different particle sizes is loaded into a mixing tank for uniform mixing, wherein the diamond micro-powder with different particle sizes comprises, in terms of mass percentage: 63% to 67% of diamond micro-powder with a particle size of 30 to 40 μm, 18% to 22% of diamond micro-powder with a particle size of 10 to 15 μm, 11% to 15% of diamond micro-powder with a particle size of 4 to 8 μm, and 1% to 3% of diamond micro-powder with a particle size of 1 to 2 μm.

[0066] Preferably, the ball-free mixing can adopt ordinary ball-free mixing technology or acoustic resonance ball-free mixing technology.

[0067] When the ordinary ball-free mixing technology is adopted, the loading amount of the diamond micro-powder is 1 / 4 to 1 / 3 of the volume of the mixing tank, the mixing rotation speed is 80 to 240 rpm, and the mixing time is greater than or equal to 4 hours.

[0068] When the acoustic resonance ball-free mixing technology is adopted, the loading amount is 1 / 4 to 1 / 3 of the volume of the mixing tank, the mixing acceleration is 50 to 60 g, the mixing frequency is 60 to 70 Hz, and the mixing time is 15 to 18 minutes. The above acoustic resonance ball-free mixing technology is based on the resonance generated by the driving system and the spring system to realize the vertical vibration of the container with low frequency and large acceleration under the condition of small input energy, to generate macroscopic vibration dispersion and microscopic acoustic flow dispersion coupling effect in the mixed material, and to have higher mixing efficiency.

[0069] Preferably, the mixing tank is made of stainless steel or other materials.

[0070] Preferably, the particle size analysis is performed on the mixed diamond micro-powder to determine the uniformity of the mixing. Specifically, after the mixed diamond micro-powder is placed flat, three samples are taken at every 120° near the edge of the tank for particle size analysis, and the uniformity of the mixing is determined according to the coincidence degree of the particle size curve. The test proves that the above particle size formula and ball-free mixing process not only can reduce the introduction of impurities in the mixing process, but also can achieve good mixing uniformity.

[0071] Preferably, the diamond micro-powder with the proportioned formula should be dried before the ball-free mixing to ensure the dispersibility and flowability of the micro-powder under the condition of ball-free mixing. Specifically, the drying temperature is 100 to 110 ℃, and the drying time is greater than or equal to 1 hour.

[0072] Preferably, the impurity removal and purification of the mixed and uniform diamond micro-powder includes using an acid mist distillation method to remove and purify the impurities of the mixed and uniform diamond micro-powder.

[0073] The acid mist distillation method can remove the impurities in the micro-powder to a large extent, and the acid mist produced by the acid mist distillation method can avoid the introduction of impurities in the acid solution, and is more suitable for further high-purity purification of a small amount of diamond micro-powder for diamond composite sheets compared with the existing acid boiling method or electrolysis method, and greatly reduces the influence of impurities in the diamond micro-powder on the performance of the diamond composite sheet.

[0074] Preferably, the acid mist distillation method specifically includes the following steps: placing the mixed and uniform diamond micro-powder on a porous partition plate in a purification bottle, the purification bottle being communicated with an acid liquid distillation bottle, and the acid liquid distillation bottle being used to generate acid mist to remove and purify the impurities of the diamond micro-powder. The acid mist generated by the acid liquid distillation bottle flows through the diamond micro-powder in the purification bottle and can fully contact and react with the impurities in the diamond micro-powder, which not only improves the impurity removal efficiency, but also reduces the loss of acid and environmental pollution, and does not introduce impurities in the acid solution into the diamond micro-powder.

[0075] Preferably, the purification bottle is also communicated with a high-purity water distillation bottle, and the high-purity water distillation bottle is used to generate water vapor to elute the residual soluble impurities and acid liquid in the diamond micro-powder. The present application also provides a high-purity water distillation bottle to generate water vapor, which can elute the residual soluble impurities and acid liquid in the diamond after the reaction of the acid and the impurities, and further improve the purity of the diamond micro-powder.

[0076] Preferably, the bottom of the acid liquid distillation bottle and the high-purity water distillation bottle is provided with a heating device, and the heating device is used to heat the acid liquid distillation bottle and the high-purity water distillation bottle to obtain acid mist and water vapor; a flow valve is arranged at the outlet of the acid liquid distillation bottle and the high-purity water distillation bottle, and the flow valve is used to control the flow of the acid mist and the water vapor.

[0077] Preferably, the flow of the acid mist and the water vapor used in the acid mist distillation method for every 100g of mixed powder is 30-50mL / min, so as to ensure that the acid mist can fully contact and react with the impurities in the diamond micro-powder, and the water vapor can fully dissolve the residual impurities and acid liquid, and further improve the purity of the diamond micro-powder.

[0078] Preferably, the acid mist distillation time is 30-60min, and the water vapor cleaning time is more than 10min, until the solution at the outlet is neutralized by using pH test paper.

[0079] Preferably, after the solution at the outlet is neutralized by using pH test paper, the diamond micro-powder is subjected to drying treatment.

[0080] Preferably, the acid solution in the acid solution distillation bottle is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid, wherein the hydrochloric acid, the sulfuric acid and the nitric acid are all of analytical pure concentration.

[0081] Preferably, the acid solution is a mixture of hydrochloric acid and nitric acid, and when the acid solution is the mixture of hydrochloric acid and nitric acid, the volume ratio of the hydrochloric acid to the nitric acid is 1:(3-4).

[0082] Preferably, the volume ratio of the hydrochloric acid to the nitric acid is 1:3. Tests show that when the analytical pure hydrochloric acid and the analytical pure nitric acid are mixed in a volume ratio of 1:3, the solubility of the impurities in the diamond powder is better.

[0083] Preferably, the diamond powder is located at the middle part of the purification bottle, the purification bottle is divided into an upper space and a lower space, the upper space is communicated with the acid solution distillation bottle and the high-purity water distillation bottle, the lower space is an acid solution condensation collection space, and an acid solution discharge port is arranged at the bottom of the lower space (i.e. the bottom of the purification bottle). The acid mist flows from top to bottom through the diamond powder, reacts with the impurities in the diamond powder, is condensed in the acid solution condensation collection space after the reaction, and flows out through the acid solution discharge port; when the water vapor is eluted, the water vapor flows from top to bottom through the diamond powder, dissolves the soluble impurities and the residual acid mist in the diamond powder after the reaction, is condensed in the acid solution condensation collection space, and flows out through the acid solution discharge port.

[0084] Preferably, in the acid mist distillation process, the upper and lower parts of the diamond powder are both provided with polytetrafluoroethylene films (i.e. before the diamond powder is laid on the porous partition plate, a layer of polytetrafluoroethylene film is laid on the porous partition plate, which is the lower polytetrafluoroethylene film; after the diamond powder is laid on the porous partition plate, another layer of polytetrafluoroethylene film is laid on the diamond powder, which is the upper polytetrafluoroethylene film), the polytetrafluoroethylene films are used for filtering the acid mist, the upper polytetrafluoroethylene film can also disperse the airflow to make the acid vapor uniformly permeate the powder; the lower polytetrafluoroethylene film also plays the roles of bearing the powder, filtering the acid mist and condensing the acid solution.

[0085] Preferably, the pore size of the upper polytetrafluoroethylene film is set to 0.4-0.8 μm, the pore size of the lower polytetrafluoroethylene film is set to 0.1-0.3 μm, and the thickness of the powder layer is set to ≤1.5 cm.

[0086] Since the upper and lower polytetrafluoroethylene films play the roles of isolation and bearing, the acid mist can effectively pass through the diamond powder, and meanwhile, the relatively fine powder can be prevented from leaking out, therefore, the pore size of the upper polytetrafluoroethylene film is set to be slightly larger, i.e. 0.4-0.8 μm, which is beneficial to the entry of the acid mist into the powder layer; the pore size of the lower polytetrafluoroethylene film is set to be slightly smaller, i.e. 0.1-0.3 μm, which can prevent the powder from leaking out. In addition, the thickness of the powder layer should not be too large, otherwise the acid mist cannot sufficiently wash the powder, which affects the purification effect.

[0087] Preferably, the impurity removal and purification of the mixed and uniform diamond micro-powder further comprises hydrogen burning treatment of the mixed and uniform diamond micro-powder, the hydrogen burning treatment being performed before the acid mist distillation step, and the hydrogen burning treatment specifically comprises passing hydrogen into the mixed and uniform diamond micro-powder and heating. The purpose of the hydrogen burning treatment is to reduce the oxides in the mixed and uniform diamond micro-powder into metals, to decompose organic impurities, to reduce the impurity content in the diamond micro-powder, and to improve the purification efficiency of the acid mist distillation.

[0088] Preferably, the temperature of the hydrogen burning treatment is 650-820°C, the treatment time is 2-4h, and the hydrogen flow rate for every 100g of the mixed powder is 50-200mL / min.

[0089] Preferably, the high-purity diamond composite sheet is obtained by compounding the diamond micro-powder after the impurity removal and purification with the cemented carbide substrate, and mainly comprises the steps of assembling the composite sheet blank, assembling the pyrophyllite synthesis block, and sintering the composite sheet.

[0090] Preferably, the step of assembling the composite sheet blank comprises: loading the dried diamond micro-powder into a metal cup, placing the cemented carbide substrate on the diamond micro-powder, and then placing another metal cup to cover the diamond micro-powder and the cemented carbide substrate to form the composite sheet blank. The material of the metal cup needs to have high-temperature chemical stability and good toughness, and is preferably niobium or titanium. The size of the metal cup is consistent with the size of the composite sheet blank.

[0091] Preferably, the step of assembling the composite sheet blank further comprises: placing the composite sheet blank into a vacuum furnace at 1450-1550°C for 1-3h to further decompose and remove trace amounts of organic impurities possibly introduced during the assembling process.

[0092] Preferably, the step of assembling the composite sheet blank further comprises: vacuum brazing the composite sheet blank after the vacuum heat treatment, and brazing and sealing the upper and lower metal cups to avoid the diamond micro-powder from being contaminated by the external environment before sintering.

[0093] Preferably, the step of assembling the pyrophyllite synthesis block comprises: placing the sealed composite sheet blank into the pyrophyllite synthesis block. The synthesis block mainly comprises an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material to achieve the high-temperature and high-pressure conditions required for sintering the diamond in the blank.

[0094] Preferably, the step of sintering the composite sheet comprises: placing the pyrophyllite synthesis block in a six-sides top press machine device, controlling the oil pressure of the device to make the surface pressure of the pyrophyllite 10.5-11GPa, and controlling the power of the device to make the internal temperature of the synthesis block reach 1600-1630°C. After sintering, demolding is performed to obtain a high-purity diamond composite sheet.

[0095] Preferably, the temperature inside the synthesis block can be measured and adjusted by connecting a type-B thermocouple outside the graphite carbon tube.

[0096] The preparation method of the present application is described below by specific examples.

[0097] Example 1

[0098] Step S101: Weigh the diamond micro-powder according to the formula, 100g, wherein 30-40μm accounts for 65%wt, 10-15μm accounts for 20%wt, 4-8μm accounts for 13%wt, and 1-2μm accounts for 2%wt. Place the mixed diamond micro-powder in a vacuum oven to dry, so as to ensure the dispersibility and flow of the diamond micro-powder under the condition of no ball mixing. The drying temperature is 100°C, and the drying time is 1h.

[0099] Step S102: No-ball mixing (ordinary no-ball mixing): Put the dried diamond micro-powder into a stainless steel tank, and the filling amount is 1 / 3 of the volume of the stainless steel tank. The mixing speed is 80rpm, and the mixing time is 8h. Take three samples from the mixed powder for particle size analysis, and determine the uniformity of the mixing according to the coincidence degree of the particle size curve. The particle size distribution curves of the three places are shown in FIG. 1. When the coincidence degree of the three curves is good, it can be determined that the diamond micro-powder is mixed uniformly. Figure 3

[0100] The total impurity content of the diamond micro-powder after no-ball mixing is 0.0169% detected by ICP. The specific impurity content is shown in Table 1.

[0101] Step S103: Hydrogen burning treatment: Put the uniformly mixed diamond micro-powder into a container with flowing hydrogen for heating treatment. The hydrogen burning treatment temperature is 650°, the treatment time is 3h, and the hydrogen flow rate is 200mL / min.

[0102] Step S104: Assembly of composite sheet blank: Put 2.2g of the dried diamond micro-powder into a niobium metal cup with an inner diameter of 16.8mm, and then place a cemented carbide substrate with a diameter of 16.6mm on it. Then, put the micro-powder and the cemented carbide substrate together into another niobium metal cup with a diameter of 17mm to form a composite sheet blank. Put the composite sheet blank into a vacuum furnace at 1550°C for 1h. Perform vacuum brazing on the composite sheet blank after vacuum heat treatment, and seal the upper and lower metal cups.

[0103] Step S105: Assembly of pyrophyllite synthesis block: Put the vacuum brazed metal cup into the pyrophyllite synthesis block, which mainly includes an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material.

[0104] ​Step S106: composite piece firing: put the phlogopite synthetic block in the six- face top press equipment, control the equipment oil pressure to make the phlogopite surface pressure 11 GPa; control the equipment power to make the internal temperature of the synthetic block reach 1600-1630℃. After firing, demolding and grinding, a high- purity diamond composite piece 1 can be obtained.

[0105] Example 2

[0106] Step S201: weigh and proportion the diamond micro powder 100g according to the formula, wherein 30-40μm accounts for 65%wt, 10-15μm accounts for 20%wt, 4-8μm accounts for 13%wt, and 1-2μm accounts for 2%wt. Put the proportioned diamond micro powder in a vacuum oven to dry to ensure the dispersibility and flow of the diamond micro powder under the condition of ball-free mixing, the drying temperature is 100℃, and the drying time is 1h.

[0107] Step S202: ball-free mixing (ordinary ball-free mixing): put the dried diamond micro powder into a stainless steel tank, the filling amount is 1 / 3 of the volume of the stainless steel tank, the mixing speed is 80rpm, and the mixing time is 8h. Take three samples of the mixed powder for particle size analysis, determine the uniformity of the mixing according to the coincidence degree of the particle size curve, and when the coincidence degree of the three curves is good, it is determined that the diamond micro powder is uniformly mixed.

[0108] Step S203: hydrogen burning treatment: put the uniformly mixed diamond micro powder into a container with flowing hydrogen for heating treatment. The hydrogen burning treatment temperature is 650°, the treatment time is 3h, and the hydrogen flow is 200mL / min.

[0109] Step S204: acid mist distillation: place the hydrogen burning treated diamond micro powder in the middle of the purification bottle 6 through a porous partition, the thickness of the diamond micro powder layer 13 is set to 1cm, and polytetrafluoroethylene films are arranged on the upper and lower surfaces of the diamond micro powder 72 for isolation and filtration. The upper polytetrafluoroethylene film 71 has a pore size of 0.45μm, and the lower polytetrafluoroethylene film 73 has a pore size of 0.22μm.

[0110] The upper part of the purification bottle 6 is connected to the acid distillation bottle 1 and the high-purity water distillation bottle 2, wherein the mixed acid is a mixture of hydrochloric acid and nitric acid, and the volume ratio of hydrochloric acid to nitric acid is 1:3. First, open the acid heater 3 and slowly heat the acid to boiling, control the steam flow through the acid mist flow valve 4 to 30mL / min, stop heating after distillation for 30min, and close the acid flow valve 4 after cooling; then open the high-purity water heater 11 and slowly heat it to boiling, adjust the water vapor flow valve 10 to 50mL / min, clean for 10min, and detect the pH value of the solution at the discharge port to be 7. Then take out the diamond micro powder and dry it in a vacuum oven to obtain high-purity diamond micro powder.

[0111] The total impurity content of the high-purity diamond powder after drying was 0.004% detected by ICP, and the specific impurity content can be seen in Table 1.

[0112] Step S205: composite blank assembly: 2.2 g of the dried diamond powder was sequentially loaded into a niobium metal cup with an inner diameter of 16.8 mm, and then a cemented carbide substrate with a diameter of 16.6 mm was placed thereon, and another niobium metal cup with a diameter of 17 mm was used to cover the diamond powder and the cemented carbide substrate to form a composite blank. The composite blank was placed in a vacuum furnace at 1550°C for 1 h, and the composite blank after vacuum heat treatment was vacuum brazed, and the upper and lower metal cups were brazed and sealed.

[0113] Step S206: assemble pyrophyllite synthesis block: the vacuum brazed metal cup was placed in a pyrophyllite synthesis block, which mainly contains an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material.

[0114] Step S207: composite sheet firing: the pyrophyllite synthesis block was placed in a six-surface press equipment, the surface pressure of the pyrophyllite was controlled to be 11 GPa by controlling the oil pressure of the equipment, and the internal temperature of the synthesis block was controlled to be 1600-1630°C by controlling the power of the equipment. After firing, demolding and grinding, a high-purity diamond composite sheet 2 was obtained.

[0115] Example 3

[0116] Step S301: according to the formula, 100 g of diamond powder was weighed and mixed, wherein 30-40 μm accounted for 65% wt, 10-15 μm accounted for 20% wt, 4-8 μm accounted for 13% wt, and 1-2 μm accounted for 2% wt. The mixed diamond powder was placed in a vacuum oven for drying to ensure the dispersibility and flow of the diamond powder under the condition of ball-free mixing. The drying temperature was 100°C, and the drying time was 1 h.

[0117] Step S302: ball-free mixing (ordinary ball-free mixing): the dried diamond powder was loaded into a stainless steel tank, and the filling amount was 1 / 3 of the volume of the stainless steel tank. The mixing speed was 80 rpm, and the mixing time was 8 h. Particle size analysis was performed on 3 samples of the mixed powder, and the uniformity of the mixing was determined according to the coincidence degree of the particle size curve. When the coincidence degree of the 3 curves was good, it was determined that the diamond powder was mixed uniformly.

[0118] Step S303: hydrogen burning treatment: the uniformly mixed diamond powder was heated in a container with flowing hydrogen. The hydrogen burning treatment temperature was 650°C, the treatment time was 3 h, and the hydrogen flow rate was 200 mL / min.

[0119] Step S304: acid mist distillation: the diamond powder after hydrogen burning treatment is arranged in the middle of the purification bottle 6 through a porous partition, the thickness of the diamond powder layer 13 is set to 1 cm, and polytetrafluoroethylene films are arranged on the upper and lower surfaces of the diamond powder 72 for isolation and filtration, wherein the upper polytetrafluoroethylene film 71 adopts a pore size of 0.45 μm, and the lower polytetrafluoroethylene film 73 adopts a pore size of 0.22 μm.

[0120] The upper part of the purification bottle 6 is connected to the acid liquid distillation bottle 1 and the high-purity water distillation bottle 2, wherein the mixed acid liquid is a mixture of hydrochloric acid and sulfuric acid, and the volume ratio of hydrochloric acid to sulfuric acid is 1:3. First, the acid liquid heater 3 is opened, and the acid liquid is slowly heated to boiling. The steam flow is controlled by the acid mist flow valve 4 to be 30 mL / min. After distillation for 30 min, the heating of the acid liquid is stopped, and after cooling, the acid liquid flow valve 4 is closed. Then, the high-purity water heater 11 is opened, and is slowly heated to boiling. The water vapor flow valve 10 is adjusted to 50 mL / min. After cleaning for 10 min, the pH value of the solution at the discharge port is detected to be 7. Then, the diamond powder is taken out and dried in a vacuum oven to obtain high-purity diamond powder.

[0121] The total impurity content of the high-purity diamond powder after drying is 0.0042% as detected by ICP. The specific impurity content is shown in Table 1.

[0122] Step S305: assembly of composite sheet blank: 2.2 g of the dried diamond powder is sequentially loaded into a niobium metal cup with an inner diameter of 16.8 mm. A cemented carbide substrate with a diameter of 16.6 mm is then placed on the diamond powder. Another niobium metal cup with a diameter of 17 mm is used to cover the diamond powder and the cemented carbide substrate to form a composite sheet blank. The composite sheet blank is placed in a vacuum furnace at 1550°C for 1 h. The composite sheet blank after vacuum heat treatment is vacuum brazed, and the upper and lower metal cups are brazed and sealed.

[0123] Step S306: assembly of pyrophyllite synthesis block: the vacuum brazed metal cup is placed in a pyrophyllite synthesis block, which mainly includes an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material.

[0124] Step S307: composite sheet firing: the pyrophyllite synthesis block is placed in a six-surface press equipment. The surface pressure of the pyrophyllite is controlled to be 11 GPa by controlling the oil pressure of the equipment. The internal temperature of the synthesis block is controlled to be 1600-1630°C by controlling the power of the equipment. After firing, demolding and grinding are performed to obtain a high-purity diamond composite sheet 3.

[0125] Example 4

[0126] Step S301: Weighing the diamond micro-powder according to the formula, 100g, wherein 30-40μm accounts for 65%wt, 10-15μm accounts for 20%wt, 4-8μm accounts for 13%wt, and 1-2μm accounts for 2%wt. The mixed diamond micro-powder is dried in a vacuum oven to ensure the dispersion and flow of the diamond micro-powder under the condition of ball-free mixing, the drying temperature is 100℃, and the drying time is 1h.

[0127] Step S402: Ball-free mixing (acoustic resonance ball-free mixing): The dried diamond micro-powder is loaded into a stainless steel tank, the loading amount is 1 / 3 of the volume of the stainless steel tank, the mixing acceleration is 50g, the mixing frequency is 60Hz, and the mixing time is 18min. The particle size of the mixed powder is analyzed at three positions, the uniformity of the mixing is determined according to the coincidence degree of the particle size curve, and the three particle size distribution curves are detected. When the coincidence degree of the three curves is good, it is determined that the diamond micro-powder is uniformly mixed.

[0128] Step S403: Hydrogen burning treatment: The uniformly mixed diamond micro-powder is heated and treated in a container with flowing hydrogen. The hydrogen burning treatment temperature is 650°, the treatment time is 3h, and the hydrogen flow rate is 200mL / min.

[0129] Step S404: Acid mist distillation: The hydrogen-burned diamond micro-powder is arranged in the middle of the purification bottle 6 through a porous partition, the thickness of the diamond micro-powder layer 13 is set to 1cm, and the upper and lower surfaces of the diamond micro-powder 72 are both arranged with polytetrafluoroethylene film for isolation and filtration. The upper polytetrafluoroethylene film 71 has a pore size of 0.45μm, and the lower polytetrafluoroethylene film 73 has a pore size of 0.22μm.

[0130] The upper part of the purification bottle 6 is connected to the acid distillation bottle 1 and the high-purity water distillation bottle 2. The mixed acid is a mixture of hydrochloric acid and nitric acid, and the volume ratio of hydrochloric acid to nitric acid is 1:3. First, open the acid heater 3 and slowly heat the acid to boiling. Control the steam flow rate to 30mL / min through the acid mist flow valve 4. Stop heating the acid after distillation for 30min. After cooling, close the acid flow valve 4. Then open the high-purity water heater 11 and slowly heat it to boiling. Adjust the water vapor flow valve 10 to 50mL / min. Clean for 10min. Detect the pH value of the solution at the discharge port. The value is 7. Then take out the diamond micro-powder and dry it in a vacuum oven to obtain high-purity diamond micro-powder.

[0131] The total impurity content of the high-purity diamond micro-powder after drying is 0.0045% as detected by ICP. See Table 1 for specific impurity content.

[0132] Step S405: Assembly of the composite blank: 2.2 g of the dried diamond powder is sequentially loaded into a niobium metal cup with an inner diameter of 16.8 mm, and then a cemented carbide substrate with a diameter of 16.6 mm is placed thereon, and the diamond powder and the cemented carbide substrate are together sleeved into a composite blank by using another niobium metal cup with a diameter of 17 mm. The composite blank is placed in a vacuum furnace at 1550°C for 1 h, and vacuum brazing is performed on the composite blank after vacuum heat treatment, and the upper and lower metal cups are brazed and sealed.

[0133] Step S406: Assembly of the pyrophyllite synthesis block: the metal cup after vacuum brazing is placed in a pyrophyllite synthesis block, which mainly comprises an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material.

[0134] Step S407: Firing of the composite sheet: the pyrophyllite synthesis block is placed in a six-surface press device, the surface pressure of the pyrophyllite is controlled to be 11 GPa by controlling the oil pressure of the device, and the internal temperature of the synthesis block is controlled to be 1600-1630°C by controlling the power of the device. After firing, demolding and grinding are performed, and a high-purity diamond composite sheet 4 is obtained.

[0135] Example 5

[0136] Step S501: The diamond powder 100 g is weighed according to the formula, wherein 30-40 μm accounts for 65% wt, 10-15 μm accounts for 20% wt, 4-8 μm accounts for 13% wt, and 1-2 μm accounts for 2% wt. The well-proportioned diamond powder is placed in a vacuum oven for drying to ensure the dispersibility and flow of the diamond powder under the condition of ball-free mixing, the drying temperature is 100°C, and the drying time is 1 h.

[0137] Step S502: Ball-free mixing (ordinary ball-free mixing): the dried diamond powder is loaded into a stainless steel tank, the loading amount is 1 / 3 of the volume of the stainless steel tank, the mixing speed is 80 rpm, and the mixing time is 8 h. Particle size analysis is performed on three samples of the mixed powder, the uniformity of the mixing is determined according to the coincidence degree of the particle size curve, and when the coincidence degree of the three curves is good, it is determined that the diamond powder is uniformly mixed.

[0138] Step S503: Hydrogen burning treatment: the uniformly mixed diamond powder is heated in a container with flowing hydrogen. The hydrogen burning treatment temperature is 650°, the treatment time is 3 h, and the hydrogen flow rate is 200 mL / min.

[0139] Step S504: acid mist distillation: the diamond powder after hydrogen burning is arranged in the middle of the purification bottle 6 through a porous partition, the thickness of the diamond powder layer 13 is set to 1 cm, and polytetrafluoroethylene films are arranged on the upper and lower surfaces of the diamond powder 72 for isolation and filtration, wherein the upper polytetrafluoroethylene film 71 has a pore size of 0.45 μm, and the lower polytetrafluoroethylene film 73 has a pore size of 0.22 μm.

[0140] The upper part of the purification bottle 6 is connected to the acid liquid distillation bottle 1 and the high-purity water distillation bottle 2, wherein the mixed acid liquid is a mixture of hydrochloric acid and nitric acid, and the volume ratio of hydrochloric acid to nitric acid is 1:3. First, the acid liquid heater 3 is opened, and the acid liquid is slowly heated to boiling. The steam flow is controlled by the acid mist flow valve 4 to be 50 mL / min. After distillation for 30 min, the acid liquid is stopped heating, and after cooling, the acid liquid flow valve 4 is closed. Then, the high-purity water heater 11 is opened, and is slowly heated to boiling. The water vapor flow valve 10 is adjusted to 50 mL / min. After cleaning for 10 min, the pH value of the solution at the outlet is detected to be 7. Then, the diamond powder is taken out and dried in a vacuum oven to obtain high-purity diamond powder.

[0141] The total impurity content of the high-purity diamond powder after drying is 0.0038% as detected by ICP. The specific impurity content is shown in Table 1.

[0142] Step S505: assembly of composite sheet blank: 2.2 g of the dried diamond powder is sequentially loaded into a niobium metal cup with an inner diameter of 16.8 mm, and then a cemented carbide substrate with a diameter of 16.6 mm is placed thereon. Another niobium metal cup with a diameter of 17 mm is used to cover the diamond powder and the cemented carbide substrate to form a composite sheet blank. The composite sheet blank is placed in a vacuum furnace at 1550°C for 1 h. The composite sheet blank after vacuum heat treatment is vacuum brazed, and the upper and lower metal cups are brazed and sealed.

[0143] Step S506: assembly of pyrophyllite synthesis block: the metal cup after vacuum brazing is placed in a pyrophyllite synthesis block, which mainly includes an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material.

[0144] Step S507: composite sheet firing: the pyrophyllite synthesis block is placed in a six-surface press equipment. The surface pressure of the pyrophyllite is controlled to be 11 GPa by controlling the oil pressure of the equipment. The internal temperature of the synthesis block is controlled to be 1600-1630°C by controlling the power of the equipment. After firing, demolding and grinding are performed to obtain a high-purity diamond composite sheet 5.

[0145] Comparative Example 1

[0146] Step S201: Weighing the diamond micro-powder according to the formula, 100g, wherein 30-40μm accounts for 65%wt, 10-15μm accounts for 20%wt, 4-8μm accounts for 13%wt, and 1-2μm accounts for 2%wt. The mixed diamond micro-powder is dried in a vacuum oven to ensure the dispersibility and flow of the diamond micro-powder under the condition of no ball mixing. The drying temperature is 100°C, and the drying time is 1h.

[0147] Step S202: The diamond micro-powder is mixed uniformly by using a hard alloy ball milling mixer. The hard alloy ball milling mixer uses the process conditions commonly used in the prior art.

[0148] The total impurity content of the diamond micro-powder after the hard alloy ball milling mixing treatment is 0.1033% by ICP detection. The specific impurity content is shown in Table 1.

[0149] Step S203: Hydrogen burning treatment: The mixed diamond micro-powder is heated and treated in a container with flowing hydrogen. The hydrogen burning treatment temperature is 650°, the treatment time is 3h, and the hydrogen flow rate is 200mL / min.

[0150] Step S204: Assembly of the composite blank: 2.2g of the dried diamond micro-powder is sequentially loaded into a niobium metal cup with an inner diameter of 16.8mm, and then a hard alloy substrate with a diameter of 16.6mm is placed thereon. Another niobium metal cup with a diameter of 17mm is used to cover the micro-powder and the hard alloy substrate together to form a composite blank. The composite blank is placed in a vacuum furnace at 1550°C for 1h. The composite blank after vacuum heat treatment is vacuum brazed, and the upper and lower metal cups are brazed and sealed.

[0151] Step S205: Assembly of pyrophyllite synthesis block: The vacuum brazed metal cup is placed in a pyrophyllite synthesis block, which mainly includes an external pyrophyllite pressure transmission material and an internal graphite carbon tube heating material.

[0152] Step S206: Composite sheet firing: The pyrophyllite synthesis block is placed in a six-surface press equipment. The surface pressure of the pyrophyllite is controlled to be 11GPa by controlling the oil pressure of the equipment. The internal temperature of the synthesis block is controlled to be 1600-1630°C by controlling the power of the equipment. After firing, demolding and grinding are performed to obtain a diamond composite sheet A.

[0153] The impurity contents of the diamond micro-powder detected in the daily production of the diamond raw powder, Example 1 and Comparative Example 1 are compared and shown in Table 1.

[0154] Table 1 Impurity content of the diamond micro-powder detected by ICP in the examples and comparative examples

[0155]

[0156] The abrasion resistance and impact resistance of the diamond compact prepared in Examples 1 to 5 and Comparative Example 1 were tested.

[0157] (1) Abrasion resistance test: The high-purity diamond compact was installed on a 25° jig, and a 1000 mm diameter rock was ground at a depth of 0.3 mm and a speed of 100 rpm. The abrasion area of the high-purity diamond compact was measured after grinding to a depth of 30 mm.

[0158] (2) Impact resistance test: The high-purity diamond compact was installed on a 25° jig, and the high-purity diamond compact was impacted multiple times with an energy of 30 J. The number of impacts at which the high-purity diamond compact was broken was measured.

[0159] The test results are shown in Table 2 below.

[0160] Table 2: Abrasion resistance and impact resistance of diamond compacts prepared by different methods

[0161] Number Worn area Impact number High purity diamond compact 1 10.5、11.2、10.8 20、22、22 High purity diamond compact 2 10.1、10.3、9.8 25、27、23 High purity diamond compact 3 10.5、10.7、11 23、26、26 High purity diamond compact 4 10.1、10.2、9.9 27、29、23 High purity diamond compact 5 10.3、9.9、10 28、30、25 Diamond compact A 11.2、11.5、12.3 23、18、19

[0162] As can be seen from Tables 1 and 2, the impurity content of the diamond micro powder can be effectively reduced, and the abrasion resistance and impact resistance of the diamond compact can be improved by the method for preparing the diamond compact according to the present application.

[0163] It should be noted that the relational terms such as "first" and "second" and the like are used only to distinguish one entity or action from another, and do not necessarily require or imply any actual relationship or order between or among the entities or actions. Also, the terms "comprises", "comprising", or any other variations thereof are intended to cover a non-exclusive inclusion, so that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0164] The present application is not limited to the above-described embodiments, and various improvements and refinements can be made by those skilled in the art without departing from the principles of the present application, and these improvements and refinements are also considered to be within the scope of the present application. The contents not described in detail in the specification are known in the art to those skilled in the art as prior art.

Claims

1. A method for producing a high-purity diamond compact, characterized by, The high-purity diamond compact includes diamond powder and a cemented carbide substrate, and the diamond powder is pretreated by a ball-free mixing method; The ball-free mixing method specifically includes the following steps: uniformly mixing different particle sizes of diamond powder in a mixing tank; the different particle sizes of diamond powder include, by mass percentage, 63-67% of diamond powder with a particle size of 30-40 μm, 18-22% of diamond powder with a particle size of 10-15 μm, 11-15% of diamond powder with a particle size of 4-8 μm, and 1-3% of diamond powder with a particle size of 1-2 μm; The ball-free mixing is selected from ordinary ball-free mixing technology or acoustic resonance ball-free mixing technology. After the diamond powder is pretreated by the ball-free mixing method, the uniformly mixed diamond powder is further purified by an acid mist distillation method. The acid mist distillation method specifically includes the following steps: placing the uniformly mixed diamond powder on a porous partition in a purification bottle, the purification bottle being in communication with an acid distillation bottle, and the acid distillation bottle being used to generate acid mist to purify the diamond powder; The diamond powder is located at an intermediate position of the purification bottle, and the purification bottle is divided into an upper space and a lower space, the upper space being in communication with the acid distillation bottle, and the lower space being an acid condensation and collection space, and the lower space being provided with an acid outlet at a bottom portion thereof; The acid distillation bottle is provided with a heating device at a bottom portion thereof, and the heating device is used to heat the acid distillation bottle to generate acid mist, the acid mist flowing from top to bottom through the diamond powder, reacting with impurities in the diamond powder, and being condensed in the lower space and then flowing out through the acid outlet; The diamond powder is provided with polytetrafluoroethylene films at upper and lower portions thereof, the upper polytetrafluoroethylene film being provided with a pore size of 0.4-0.8 μm, the lower polytetrafluoroethylene film being provided with a pore size of 0.1-0.3 μm, and a thickness of the diamond powder layer being ≤1.5 cm; The purification bottle is further in communication with a high-purity water distillation bottle, and the high-purity water distillation bottle is used to generate water vapor to elute soluble impurities and residual acid in the diamond powder; In use, the heating device at the bottom portion of the acid distillation bottle is first turned on, the acid is slowly heated to boiling, the steam flow is controlled by an acid mist flow valve to be 30 mL / min, the acid is stopped heating after distillation for 30 min, the acid flow valve is closed after cooling, the high-purity water heater at the bottom portion of the high-purity water distillation bottle is then turned on, the high-purity water is slowly heated to boiling, the water vapor flow valve is adjusted to be 50 mL / min, the washing is performed for 10 min, the pH value of the solution at the outlet is detected to be 7, the diamond powder is taken out and dried, and high-purity diamond powder is obtained.

2. The method of claim 1, wherein the high purity diamond compact is prepared by the steps of: The acid distillation bottle is filled with acid, and the acid is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid. ​ 3. The method of producing a high-purity diamond compact according to claim 1 or 2, wherein The method further includes the following steps: The purified diamond powder is combined with the cemented carbide substrate to obtain the high-purity diamond compact.

Images