A method for coating diamond powder on the surface of cemented carbide powder

Abstract

The present invention discloses a method for coating diamond powder on the surface of cemented carbide powder, comprising the following steps: vacuum pressureless sintering of diamond powder with an average particle size of 0.5-1.5 μm to obtain a core-shell structure of diamond@graphite, then oxidizing the surface graphite to graphene oxide to obtain a modified diamond powder with a core-shell structure of diamond@graphene oxide; impregnating cemented carbide powder with an average particle size of 13-15 μm with dilute acid, and then impregnating with an alcohol solution to obtain hydroxylated cemented carbide powder; uniformly dispersing the modified diamond powder and the hydroxylated cemented carbide powder in anhydrous ethanol, and then performing electrophoretic deposition to deposit the diamond powder on the surface of the cemented carbide powder. The method solves the problem of poor film-based bonding ability of coating tool materials prepared by the prior art, while significantly improving the bonding strength between diamond powder and cemented carbide powder, which is expected to further extend tool life and improve various cutting and mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of tool materials, and particularly relates to a method for coating diamond powder on the surface of cemented carbide powder. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Cutting tools with diamond powder coated on the surface of cemented carbide powder combine the high hardness and wear resistance of diamond with the high bending strength of cemented carbide. They can be used for precision machining of non-ferrous metals, such as high-silicon aluminum alloy materials widely used in automobiles, motorcycles and military industries.

[0004] Coating methods commonly involve depositing diamond films on bulk substrates. PVD, CVD, and PCVD technologies are relatively mature and serve as the primary methods for depositing various diamond and amorphous carbon films. However, diamond films deposited using these technologies often rely solely on van der Waals forces between the coating and the substrate, resulting in low bonding strength and easy flaking of diamond powder. This degrades the tool's cutting and mechanical properties, and the tool wear is severe after the diamond coating has flaked off, reducing tool life. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a method for coating diamond powder on the surface of cemented carbide powder.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for coating diamond powder on the surface of cemented carbide powder comprises the following steps: vacuum pressureless sintering of diamond powder with an average particle size of 0.5-1.5 μm to obtain a diamond@graphite core-shell structure, and then oxidizing the surface graphite to graphene oxide to obtain a modified diamond powder with a diamond@graphene oxide core-shell structure;

[0008] The cemented carbide powder having an average particle size of 13-15 μm is impregnated with dilute acid and then impregnated with an alcohol solution to obtain hydroxylated cemented carbide powder.

[0009] The modified diamond powder and the hydroxylated cemented carbide powder are uniformly dispersed in anhydrous ethanol, and then electrophoresis deposition is performed to deposit the diamond powder on the surface of the cemented carbide powder to obtain the product.

[0010] The carboxyl groups on the surface of the modified diamond powder with diamond@graphene oxide core-shell structure can ionize to -COO - It is negatively charged and can be used for anodic deposition.

[0011] Electrophoresis is performed using a DC constant voltage electrophoresis method. In an alkaline environment, the surface of the diamond / graphene oxide in the dispersion medium is negatively charged, and the particles repel each other to form a uniform and stable electrophoretic suspension. The WC powder first settles on the anode plate below and becomes positively charged.

[0012] After power is applied, under the action of the electric field, the negatively charged diamond powder will be deposited on the surface of the cemented carbide powder. The epoxy functional groups such as carboxyl and hydroxyl groups on the graphene oxide on the diamond surface will condense with the hydroxyl groups on the surface of the cemented carbide powder to form chemical bond structures such as COO-W and COW. The WC powder with positive charge will combine with the negatively charged diamond powder, and the surface of the WC powder has a high surface energy. After adsorbing the diamond powder, it will reach a stable state with lower energy. At the same time, relying on the chemical adsorption formed by covalent bonds and the physical adsorption formed by van der Waals forces, the interfacial bonding strength is greatly enhanced.

[0013] Diamond powder is sintered in vacuum without pressure to form a diamond / graphite core-shell structure. The graphite layer on the surface of the diamond powder is oxidized to graphene oxide using the Hermes method. Since graphene oxide contains a large amount of -COOH, it can ionize to produce -COO - , so that the diamond powder has a negative charge, and the carbide powder produces -OH on its surface after being impregnated with dilute acid. With the help of the electrophoretic deposition process, upper and lower horizontal plates are set up, with the upper plate connected to the cathode and the lower plate connected to the anode. The carbide powder is first deposited on the lower anode plate and becomes positively charged. After power is applied, under the action of the electric field, it is finally deposited on the surface of the carbide powder. The carboxyl and hydroxyl groups on the diamond surface will condense with the hydroxyl groups on the surface of the carbide powder to form chemical bonds such as COO-W and COW. This adsorption is chemical adsorption. Since the WC powder is positively charged and combines with the negatively charged diamond powder, and the surface of the WC powder has a high surface energy, it reaches a low-energy stable state after adsorbing the diamond powder. This adsorption is physical adsorption. At the same time, the chemical adsorption formed by covalent bonds and the physical adsorption formed by van der Waals forces enhance the interfacial bonding strength.

[0014] In some embodiments, the vacuum pressureless sintering temperature is 1500-1700° C., and the sintering time is 10-30 minutes.

[0015] Preferably, the temperature of vacuum pressureless sintering is 1550-1650° C., and the sintering time is 10-20 minutes.

[0016] In some embodiments, the surface graphite of diamond@graphite is oxidized to graphene oxide using the Hermes method.

[0017] In some embodiments, the method further includes ball milling the WC powder having an average particle size of 13-15 μm to prevent the WC powder from agglomerating and affecting the coating effect.

[0018] Preferably, the ball milling speed is 300-400 r / min.

[0019] In some embodiments, the cemented carbide powder is WC powder. The main component of cemented carbide is WC, and WC powder can be used as a tool material.

[0020] In some embodiments, cemented carbide powder is added to dilute acid, ultrasonically dispersed for 20-40 minutes, and then immersed.

[0021] Preferably, the dilute acid is hydrofluoric acid with a mass concentration of 40%.

[0022] In some embodiments, the volume ratio of ethanol to water in the alcohol solution is 1:1-1:3.

[0023] Preferably, the cemented carbide powder after the dilute acid treatment is washed with the alcohol solution 3-8 times, preferably 4-6 times. During the washing process of the cemented carbide powder with the ethanol solution, ultrasonic dispersion and mechanical stirring are performed, followed by high-speed centrifugation to pour out the supernatant.

[0024] In some embodiments, during the electrophoretic deposition process, the mass ratio of the modified diamond powder to the hydroxylated cemented carbide powder is 1:6-8.

[0025] Preferably, during the electrophoretic deposition process, the pH value of the electrophoretic solution is adjusted to 9-11.

[0026] Preferably, the voltage of electrophoretic deposition is 40-60 V, and the time of a single electrophoresis is 3-5 min.

[0027] More preferably, the electrophoretic deposition is repeated 7-8 times.

[0028] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0029] The present invention can solve the problem of easy peeling of the surface coating of the block substrate, so that the tool has the high bending strength of cemented carbide and the high hardness and wear resistance of diamond, which is expected to improve the various cutting performances of the tool while significantly extending the tool life.

[0030] By modifying the powder surface with the help of electrophoretic deposition process, the cemented carbide powder and diamond powder rely on both chemical adsorption formed by covalent bonds and physical adsorption formed by van der Waals forces. Compared with physical adsorption formed by van der Waals forces alone, the interface bonding strength is greatly enhanced.

[0031] The surface coating does not introduce other ionic impurities, which improves the purity of the composite powder. The graphene on the surface of the diamond powder serves as a reinforcing phase of the coating tool material, which can improve its friction and wear characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 This is the XRD pattern of the diamond prepared in Example 1 of the present invention.

[0034] Figure 2 This is the XRD pattern of diamond / graphite prepared in Example 1 of the present invention.

[0035] Figure 3 This is the XRD pattern of diamond / graphene oxide prepared in Example 1 of the present invention.

[0036] Figure 4 TEM images of diamond / graphite in Example 1 of the present invention, wherein (a) is a TEM image of the diamond / graphite surface, (b) is an enlarged image of the boxed area in Figure a, and (c) is a selected area electron diffraction image of the boxed area in Figure a.

[0037] Figure 5 These are SEM morphology images of the cemented carbide powder before and after coating in Example 1 of the present invention, wherein (a) is before coating and (b) is after coating.

[0038] Figure 6 These are the total EDS and point scanning EDS energy spectra in Example 1 of the present invention, where (a) is the overall SEM morphology of the coated powder, (b) is the total EDS energy spectrum of Figure a, (c) is the local SEM morphology of the coated powder surface, and (d) is the point scanning EDS energy spectrum corresponding to spectrum 1 in Figure c.

[0039] Figure 7 Figures 1 and 2 are SEM morphologies of the unmodified coating powder and the modified coating powder after ball milling, respectively. (a) is the SEM image of the unmodified coating powder after ball milling, and (b) is the SEM image of the modified coating powder after ball milling. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0041] The present invention will be further described below with reference to the embodiments.

[0042] Example 1

[0043] Diamond powder surface modification:

[0044] (1) Graphitization of diamond powder surface

[0045] Weigh 20g of single crystal diamond powder with an average particle size of 1μm and use vacuum pressureless sintering with a heating rate of 30℃ / min in the range of 20-800℃, 20℃ / min in the range of 800-1500℃, and 10℃ / min in the range of 1500-1600℃. Keep the temperature at 1600℃ under vacuum pressureless conditions for 15 minutes and then cool it in the furnace to obtain a diamond / graphite core-shell structure.

[0046] (2) Preparation of graphene oxide from graphite layer on the surface of diamond powder

[0047] Add 100mL of concentrated sulfuric acid to a beaker. Add 4g of solid sodium nitrate in a 0°C water bath. Stir at this constant temperature for 30 minutes, then add 10g of graphitized diamond powder. Then, slowly and continuously add 20g of solid potassium permanganate over 20 minutes. Raise the water bath temperature, stir at 40°C for 6 hours, then slowly and continuously add 300mL of deionized water in an 80°C water bath, stirring continuously for 1 hour. Remove the beaker, wait for the mixed solution to cool to room temperature, then add 40mL of 30% hydrogen peroxide solution dropwise. Let the mixture stand to separate, and pour off the supernatant. Then, add 30mL of 37.5% hydrochloric acid. Ultrasonic dispersion and mechanical stirring are performed, and the mixture is allowed to separate. The supernatant is then poured off. Deionized water was added to the beaker, and ultrasonic dispersion and mechanical stirring were performed again. The suspension was then centrifuged at high speed, with the centrifugal speed set at 5000 r / min and the centrifugal time set at 5 min. The supernatant was poured out. After repeating this process five times, the diamond / graphene oxide dispersion was placed in a freeze dryer with a cold trap temperature of -50°C for freeze drying to finally obtain diamond / graphene oxide powder.

[0048] (3) Surface hydroxylation of cemented carbide powder

[0049] 60 g of WC powder with a particle size of 13-15 μm was weighed, ball-milled for 24 h at a ball-milling speed of 350 r / min, dried and sieved, placed in a beaker and added with 40 mL (40%) hydrofluoric acid, ultrasonically dispersed for 30 min and immersed, a mixed solution of water and ethanol was added to the beaker, ultrasonically dispersed and mechanically stirred, and then centrifuged at high speed. The parameters of the centrifugation process were set the same as in step (2), repeated 5 times, and finally placed in a vacuum drying oven to dry and sieve, with the drying temperature set at 120 ° C to obtain hydroxylated WC powder.

[0050] Design an electrophoretic deposition device with two electrodes placed horizontally up and down. The upper electrode is connected to the cathode and the lower electrode is connected to the anode. The electrode area is 0.013m2 , the spacing is 40 mm, and electrophoresis is performed using a DC constant voltage electrophoresis method.

[0051] The process steps of electrophoretic deposition:

[0052] (1) Weigh 5 g of modified diamond powder and 30 g of cemented carbide powder into a beaker, add 500 mL of anhydrous ethanol, adjust the pH value of the electrophoresis solution to 10, and perform ultrasonic dispersion and mechanical stirring for 30 min to form a uniform and stable suspension.

[0053] (2) The electrophoresis voltage was set to 50 V, the electrophoresis current was set to 700 mA, and the single electrophoresis time was set to 5 min after power was turned on. Ultrasonic dispersion and mechanical stirring were then performed for 3 min, and the next electrophoretic deposition was performed. This was repeated 7 times.

[0054] (3) The electrophoretic suspension is placed in a freeze dryer with a cold trap temperature of -50°C for freeze drying, and finally the surface-coated diamond powder of the cemented carbide powder is obtained.

[0055] like Figure 1 As shown in the figure, the characteristic absorption peaks of diamond can be observed, and the crystal planes corresponding to 2θ=43.98° and 75.28° are (111) and (220). Figure 2 As shown in Figure 2, after vacuum pressureless sintering, the characteristic absorption peak of graphite can be observed. The crystal plane corresponding to 2θ = 26.13° is (002). At the same time, the characteristic absorption peak of diamond can be observed, as shown in Figure 2. Figure 3 As shown, after oxidation by the Hermes method, the characteristic absorption peak of graphene oxide 2θ = 11.66° can be observed, which corresponds to the (001) crystal plane of graphene oxide. The characteristic absorption peak of diamond can also be observed.

[0056] like Figure 4 As shown, the lattice fringes of diamond (111) and graphite (002) as well as the selected area electron diffraction patterns of diamond and graphite can be observed, indicating that the graphitization preparation of the diamond surface is successful.

[0057] like Figure 5 The figure shows the morphology of the diamond coating on the surface of the cemented carbide powder in Example 1. The cemented carbide powder is completely coated, the substrate is not exposed, and the coating is uniform.

[0058] like Figure 6 The following are the total EDS spectrum and point scanning EDS spectrum of the diamond coating on the surface of the cemented carbide powder in Example 1. C, W and O elements can be observed, indicating that the surface powder is diamond and the coated particles are WC.

[0059] like Figure 7As shown in the figure, after a certain period of ball milling, the surface of the modified cemented carbide powder is coated with diamond composite powder, and the coating effect is still good. The coating of the unmodified powder is severely peeled off, and most of the matrix is ​​exposed, indicating that the bonding between the modified powders is quite strong.

[0060] Example 2

[0061] Diamond powder surface modification:

[0062] (1) Graphitization of diamond powder surface

[0063] Weigh 20g of single-crystal diamond powder with an average particle size of 1μm and use vacuum pressureless sintering with a heating rate of 30°C / min in the range of 20-800°C, 20°C / min in the range of 800-1500°C, and 10°C / min in the range of 1500-1600°C. Hold the mixture at 1600°C under vacuum pressureless conditions for 15 minutes and then cool it in the furnace to obtain a diamond / graphite core-shell structure.

[0064] (2) Preparation of graphene oxide from graphite layer on the surface of diamond powder

[0065] Add 100mL of concentrated sulfuric acid to a beaker. In a 0°C water bath, add 4g of solid sodium nitrate. Stir at this constant temperature for 30 minutes, then add 10g of graphitized diamond powder. Then, slowly and continuously add 20g of solid potassium permanganate over 20 minutes. The water bath temperature is then raised, and after stirring at 40°C for 5 hours, 300mL of deionized water is slowly and continuously added dropwise in an 80°C water bath, stirring continuously for 1 hour. Remove the beaker, wait for the mixed solution to cool to room temperature, then add 40mL of 30% hydrogen peroxide solution dropwise. Allow the mixture to separate into layers, and pour off the supernatant. Then, add 30mL of 37.5% hydrochloric acid. Ultrasonic dispersion and mechanical stirring are performed, and the mixture is allowed to separate into layers. The supernatant is then poured off. Deionized water was added to the beaker, and ultrasonic dispersion and mechanical stirring were performed again. The suspension was then centrifuged at high speed, with the centrifugal speed set at 5000 r / min and the centrifugal time set at 5 min. The supernatant was poured out. After repeating this process five times, the diamond / graphene oxide dispersion was placed in a freeze dryer with a cold trap temperature of -50°C for freeze drying to finally obtain diamond / graphene oxide powder.

[0066] (3) Surface hydroxylation of cemented carbide powder

[0067] 60 g of WC powder with a particle size of 13-15 μm was weighed, ball milled for 24 h at a ball mill speed of 350 r / min, dried and sieved, placed in a beaker and added with 40 mL (40%) hydrofluoric acid, ultrasonically dispersed for 30 min and immersed, a mixed solution of water and ethanol was added to the beaker, ultrasonically dispersed and mechanically stirred, and then centrifuged at high speed. The parameters of the centrifugation process were set the same as in step (2), repeated 3 times, and finally placed in a vacuum drying oven to dry and sieve, with the drying temperature set at 120 ° C to obtain hydroxylated WC powder.

[0068] Design an electrophoretic deposition device with two electrodes placed horizontally up and down. The upper electrode is connected to the cathode and the lower electrode is connected to the anode. The electrode area is 0.013m 2 , the spacing is 40 mm, and electrophoresis is performed using a DC constant voltage electrophoresis method.

[0069] The process steps of electrophoretic deposition:

[0070] (1) Weigh 5 g of modified diamond powder and 30 g of cemented carbide powder into a beaker, add 500 mL of anhydrous ethanol, adjust the pH of the electrophoresis solution to 10, and perform ultrasonic dispersion and mechanical stirring for 30 min to form a uniform and stable suspension.

[0071] (2) The electrophoresis voltage was set to 30 V, the electrophoresis current was set to 500 mA, and the single electrophoresis time was 5 min after power was turned on. Ultrasonic dispersion and mechanical stirring were then performed for 3 min, and the next electrophoretic deposition was performed. This was repeated 9 times.

[0072] (3) The electrophoretic suspension is placed in a freeze dryer with a cold trap temperature of -50°C for freeze drying, and finally the surface-coated diamond powder of the cemented carbide powder is obtained.

[0073] Example 3

[0074] Diamond powder surface modification:

[0075] (1) Graphitization of diamond powder surface

[0076] Weigh 20g of single crystal diamond powder with an average particle size of 1μm and use vacuum pressureless sintering with a heating rate of 30℃ / min in the range of 20-800℃, 20℃ / min in the range of 800-1500℃, and 10℃ / min in the range of 1500-1600℃. Keep the temperature at 1600℃ under vacuum pressureless conditions for 15 minutes and then cool it in the furnace to obtain a diamond / graphite core-shell structure.

[0077] (2) Preparation of graphene oxide from graphite layer on the surface of diamond powder

[0078] Add 100mL of concentrated sulfuric acid to a beaker. Add 4g of solid sodium nitrate in a 0°C water bath. Stir at this constant temperature for 30 minutes, then add 10g of graphitized diamond powder. Then, slowly and continuously add 20g of solid potassium permanganate over 20 minutes. Raise the water bath temperature, stir at 40°C for 6 hours, then slowly and continuously add 300mL of deionized water in an 80°C water bath, stirring continuously for 1 hour. Remove the beaker, wait for the mixed solution to cool to room temperature, then add 40mL of 30% hydrogen peroxide solution dropwise. Let the mixture stand to separate, and pour off the supernatant. Then, add 30mL of 37.5% hydrochloric acid. Ultrasonic dispersion and mechanical stirring are performed, and the mixture is allowed to separate. The supernatant is then poured off. Deionized water was added to the beaker, and ultrasonic dispersion and mechanical stirring were performed again. The suspension was then centrifuged at high speed, with the centrifugal speed set at 5000 r / min and the centrifugal time set at 5 min. The supernatant was poured out. After repeating this process five times, the diamond / graphene oxide dispersion was placed in a freeze dryer with a cold trap temperature of -50°C for freeze drying to finally obtain diamond / graphene oxide powder.

[0079] (3) Surface hydroxylation of cemented carbide powder

[0080] 60 g of WC powder with a particle size of 13-15 μm was weighed, ball-milled for 24 h at a ball-milling speed of 350 r / min, dried and sieved, placed in a beaker and added with 40 mL (40%) hydrofluoric acid, ultrasonically dispersed for 30 min and immersed, a mixed solution of water and ethanol was added to the beaker, ultrasonically dispersed and mechanically stirred, and then centrifuged at high speed. The parameters of the centrifugation process were set the same as in step (2), repeated 5 times, and finally placed in a vacuum drying oven to dry and sieve, with the drying temperature set at 120 ° C to obtain hydroxylated WC powder.

[0081] Design an electrophoretic deposition device with two electrodes placed horizontally up and down. The upper electrode is connected to the cathode and the lower electrode is connected to the anode. The electrode area is 0.013m 2 , the spacing is 40 mm, and electrophoresis is performed using a DC constant voltage electrophoresis method.

[0082] The process steps of electrophoretic deposition:

[0083] (1) Weigh 5 g of modified diamond powder and 40 g of cemented carbide powder into a beaker, add 500 mL of anhydrous ethanol, adjust the pH of the electrophoresis solution to 10, and perform ultrasonic dispersion and mechanical stirring for 30 min to form a uniform and stable suspension.

[0084] (2) The electrophoresis voltage was set to 50 V, the electrophoresis current was set to 700 mA, and the single electrophoresis time was set to 5 min after power was turned on. Ultrasonic dispersion and mechanical stirring were then performed for 3 min, and the next electrophoretic deposition was performed. This was repeated 7 times.

[0085] (3) The electrophoretic suspension is placed in a freeze dryer with a cold trap temperature of -50°C for freeze drying, and finally the surface-coated diamond powder of the cemented carbide powder is obtained.

[0086] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for coating diamond powder on the surface of cemented carbide powder, characterized in that: The method comprises the following steps: vacuum pressureless sintering of diamond powder with an average particle size of 0.5-1.5 μm to obtain a diamond@graphite core-shell structure, and then oxidizing the surface graphite to graphene oxide to obtain a modified diamond powder with a diamond@graphene oxide core-shell structure; The cemented carbide powder having an average particle size of 13-15 μm is impregnated with dilute acid and then impregnated with an alcohol solution to obtain hydroxylated cemented carbide powder. The modified diamond powder and the hydroxylated cemented carbide powder are uniformly dispersed in anhydrous ethanol, and then electrophoretic deposition is performed to deposit the diamond powder on the surface of the cemented carbide powder to obtain; The heating rate of vacuum pressureless sintering is 30℃ / min in the range of 20-800℃, 20℃ / min in the range of 800-1500℃, and 10℃ / min in the range of 1500-1600℃; The cemented carbide powder is WC powder; During the electrophoretic deposition process, the mass ratio of modified diamond powder to hydroxylated cemented carbide powder is 1:6-8.

2. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The temperature of vacuum pressureless sintering is 1500-1700℃, and the sintering time is 10-30min.

3. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The temperature of vacuum pressureless sintering is 1550-1650℃, and the sintering time is 10-20min.

4. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The surface graphite of diamond@graphite was oxidized to graphene oxide using the Hermes method.

5. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The method further comprises the step of ball milling WC powder having an average particle size of 13-15 μm.

6. The method for coating diamond powder on the surface of cemented carbide powder according to claim 5, characterized in that: The ball mill speed is 300-400r / min.

7. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: After adding cemented carbide powder into dilute acid, ultrasonically disperse it for 20-40 minutes and then immerse it.

8. The method for coating diamond powder on the surface of cemented carbide powder according to claim 7, characterized in that: The dilute acid is hydrofluoric acid, and its mass concentration is 40%.

9. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: In the alcohol solution, the volume ratio of ethanol to water is 1:1-1:

3.

10. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The cemented carbide powder after the dilute acid treatment is washed with an alcohol solution 3-8 times.

11. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The cemented carbide powder after the dilute acid treatment is washed with an alcohol solution 4-6 times.

12. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: During the electrophoretic deposition process, the pH value of the electrophoretic solution was adjusted to 9-11.

13. The method for coating diamond powder on the surface of cemented carbide powder according to claim 1, characterized in that: The voltage of electrophoretic deposition is 40-60V, and the single electrophoresis time is 3-5min.

14. The method for coating diamond powder on the surface of cemented carbide powder according to claim 13, characterized in that: The electrophoretic deposition was repeated 7-8 times.

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