Diamond particle with surface plated with aluminum nitride / aluminum carbide coating and preparation method of diamond particle

Abstract

The invention belongs to the technical field of ceramic coatings, and provides a diamond particle with the surface plated with an aluminum nitride / aluminum carbide coating and a preparation method of the diamond particle. The method comprises the following steps: mixing diamond particles, aluminum powder and melamine powder to obtain mixed powder; placing the mixed powder in a closed device to obtain closed mixed powder; and the closed mixed powder is subjected to heat treatment under the protective atmosphere, and the diamond particles with the surfaces plated with the aluminum nitride / aluminum carbide coatings are obtained. The raw materials of the coating are low in cost, and the aluminum powder and the melamine powder are adopted as the raw materials of the coating, so that the cost is low, and the raw materials are easy to obtain; a simple sealing means is combined with a high-temperature heat treatment process, so that the process and operation are simple and convenient, and large-scale production is easy to realize; by optimizing the raw material ratio and heat treatment process parameters, controllable adjustment of the coating can be achieved, and the requirements of different application fields for diamond performance are met.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic coating, and particularly relates to diamond particles with a surface coated with aluminum nitride / aluminum carbide coating and a preparation method thereof. Background Art

[0002] As one of the hardest materials in nature, diamond has a wide range of applications in cutting, grinding, drilling and other fields due to its excellent mechanical properties and thermal stability. Given the significant lack of wettability between diamond and other materials, the bonding strength between diamond and the binder is quite weak. This characteristic will be significantly manifested as the easy detachment of diamond particles during the use of tools, resulting in a significant reduction in the service life of diamond tools. Therefore, it is usually necessary to modify the surface of diamond, and surface coating of diamond particles is a commonly used technical means.

[0003] In recent years, significant progress has been made in the coating technology of diamond particles. Traditional coating methods include electroplating, electroless plating, chemical vapor deposition, micro evaporation plating, etc. The above coating technologies mainly achieve metal coatings, and the technology is relatively mature. The surface coating of diamond with metal is mainly applied to diamond products with metal binders and resin binders. For diamond products with ceramic binders, especially abrasive tools, diamond particles need to be coated with ceramic coatings on the surface. At present, the main method for coating ceramic coatings is the sol-gel process. The disadvantages of this technology are high raw material costs, complex processes, and weak coating adhesion.

[0004] Therefore, it is of great research and application value to develop a method for coating ceramic materials on the surface of diamond that is both economical and efficient. Summary of the Invention

[0005] The purpose of the present invention is to provide diamond particles with a surface coated with aluminum nitride / aluminum carbide coating and a preparation method thereof in order to overcome the deficiencies of the prior art.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method for diamond particles with a surface coated with aluminum nitride / aluminum carbide coating, comprising the following steps:

[0008] 1) Mix diamond particles, aluminum powder and melamine powder to obtain a mixed powder;

[0009] 2) Place the mixed powder in a closed device to obtain a closed mixed powder;

[0010] 3) Heat-treat the closed mixed powder under a protective atmosphere to obtain diamond particles with a surface coated with aluminum nitride / aluminum carbide coating.

[0011] Preferably, the particle size of the diamond particles in step 1) is 50 - 300 μm, the particle size of the aluminum powder is 50 - 100 μm, and the purity of the aluminum powder is ≥ 99 wt%.

[0012] Preferably, the mass ratio of the aluminum powder to the melamine powder in step 1) is 1:2 - 4, and the mass fraction of the diamond particles in the mixed powder is 20 - 60%.

[0013] Preferably, the rotation speed of the mixing in step 1) is 200 - 300 r / min, the mixing time is 22 - 26 h, and during the mixing process, the mass ratio of the total mass of the diamond particles, aluminum powder, and melamine powder to the mass of the grinding balls is 1:10 - 20.

[0014] Preferably, the specific process of placing the mixed powder in a closed device in step 2) is as follows: the mixed powder is put into a bearing steel sleeve, both ends of the bearing steel sleeve are sealed with stainless steel gaskets, and then the stainless steel gaskets are clamped with a tiger clamp;

[0015] The thickness of the bearing steel sleeve is 3 - 4 mm, the length of the bearing steel sleeve is less than 2 / 3 of the opening of the tiger clamp; the outer diameter of the bearing steel sleeve is similar to the wrapping length of the tiger clamp; the thickness of the stainless steel gasket is 2 - 4 mm.

[0016] Preferably, the protective atmosphere in step 3) is an argon atmosphere or a nitrogen atmosphere, the purity of the protective atmosphere is 99 - 99.9%, and the flow rate of the protective atmosphere is 50 - 100 ppm.

[0017] Preferably, the heat treatment in step 3) includes a first heat treatment and a second heat treatment. The temperature of the first heat treatment is 550 - 600 °C, and the time of the first heat treatment is 1 - 2 h; the temperature of the second heat treatment is 900 - 1000 °C, and the time of the second heat treatment is 1 - 2 h.

[0018] Preferably, the heating rate of the heat treatment in step 3) is 10 - 20 °C / min.

[0019] The present invention also provides diamond particles with an aluminum nitride / aluminum carbide coating prepared by the preparation method described above.

[0020] The beneficial effects of the present invention include the following points:

[0021] 1) The raw material cost of the coating of the present invention is relatively low. Using aluminum powder and melamine powder as the raw materials of the coating, the cost is low and it is easy to obtain.

[0022] 2) The present invention adopts simple sealing means and combines with a high-temperature heat treatment process. The process and operation are simple and it is easy to realize large-scale production.

[0023] 3) By optimizing the raw material ratio and heat treatment process parameters, the present invention can achieve controllable adjustment of the coating, meeting the requirements of diamond performance in different application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a drawing of the tiger clamp, bearing steel sleeve and stainless steel gasket of the present invention. Among them, a is the tiger clamp, b is the bearing steel sleeve, and c is the stainless steel gasket;

[0025] Figure 2 It is the XRD pattern of the diamond particles coated with aluminum nitride / aluminum carbide coating in Example 1;

[0026] Figure 3 It is the SEM pattern of the diamond particles coated with aluminum nitride / aluminum carbide coating in Example 1;

[0027] Figure 4 It is the SEM pattern of the diamond particles coated with aluminum nitride / aluminum carbide coating in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention provides a method for preparing diamond particles with a surface coated with aluminum nitride / aluminum carbide coating, comprising the following steps:

[0029] 1) Mix diamond particles, aluminum powder and melamine powder to obtain a mixed powder;

[0030] 2) Place the mixed powder in a closed device to obtain a closed mixed powder;

[0031] 3) Heat-treat the closed mixed powder under a protective atmosphere to obtain diamond particles with a surface coated with aluminum nitride / aluminum carbide coating.

[0032] In the present invention, the particle size of the diamond particles in step 1) is preferably 50 - 300 μm, more preferably 100 - 250 μm, and even more preferably 150 - 200 μm. The particle size of the aluminum powder is preferably 50 - 100 μm, more preferably 60 - 90 μm, and even more preferably 70 - 80 μm. The purity of the aluminum powder is preferably ≥99 wt%, more preferably ≥99.2 wt%.

[0033] In the present invention, the mass ratio of the aluminum powder to the melamine powder in step 1) is preferably 1:2 - 4, more preferably 1:2.5 - 3.5, and even more preferably 1:3. The mass fraction of the diamond particles in the mixed powder is preferably 20 - 60%, more preferably 30 - 50%, and even more preferably 40%.

[0034] In the present invention, the purity of the melamine is analytical pure.

[0035] In the present invention, the rotation speed of the mixing in step 1) is preferably 200 - 300 r / min, more preferably 220 - 280 r / min, and even more preferably 250 - 260 r / min; the mixing time is preferably 22 - 26 h, more preferably 23 - 25 h, and even more preferably 24 h; during the mixing process, the mass ratio of the total mass of diamond particles, aluminum powder and melamine powder to the mass of grinding balls is preferably 1:10 - 20, more preferably 1:12 - 18, and even more preferably 1:15 - 16; the material of the grinding balls is preferably agate or stainless steel, and the diameter of the grinding balls is preferably 6 mm or 10 mm.

[0036] In the present invention, the mixing in step 1) is preferably carried out in a three-dimensional swing ball mill.

[0037] In the present invention, the specific process of placing the mixed powder in a closed device in step 2) is preferably as follows: the mixed powder is put into a bearing steel sleeve, both ends of the bearing steel sleeve are sealed with stainless steel gaskets, and then the stainless steel gaskets are clamped with a tiger clamp.

[0038] The thickness of the bearing steel sleeve is preferably 3 - 4 mm, more preferably 3.2 - 3.8 mm, and even more preferably 3.5 - 3.6 mm; the length of the bearing steel sleeve is preferably less than 2 / 3 of the opening of the tiger clamp; the outer diameter of the bearing steel sleeve is preferably close to the wrapping length of the tiger clamp; the thickness of the stainless steel gasket is preferably 2 - 4 mm, more preferably 2.5 - 3.5 mm, and even more preferably 3 mm.

[0039] In the present invention, the protective atmosphere in step 3) is preferably an argon atmosphere or a nitrogen atmosphere, the purity of the protective atmosphere is preferably 99 - 99.9%, and the flow rate of the protective atmosphere is preferably 50 - 100 ppm, more preferably 60 - 90 ppm, and even more preferably 70 - 80 ppm.

[0040] In the present invention, the heat treatment in step 3) preferably includes a first heat treatment and a second heat treatment. The temperature of the first heat treatment is preferably 550 - 600 °C, more preferably 560 - 590 °C, and even more preferably 570 - 580 °C; the time of the first heat treatment is preferably 1 - 2 h, more preferably 1.5 h; the temperature of the second heat treatment is preferably 900 - 1000 °C, more preferably 920 - 980 °C, and even more preferably 950 - 960 °C; the time of the second heat treatment is preferably 1 - 2 h, more preferably 1.5 h.

[0041] In the present invention, the heating rate of the heat treatment in step 3) is preferably 10 - 20 °C / min, more preferably 12 - 18 °C / min, and even more preferably 15 - 16 °C / min.

[0042] In the present invention, after the heat treatment is completed, it is naturally cooled to room temperature, the tiger clamp is taken out, and the diamond particles coated with aluminum nitride / aluminum carbide coating are separated by a sieve.

[0043] The present invention also provides diamond particles with a surface coated with an aluminum nitride / aluminum carbide coating prepared by the preparation method described above.

[0044] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] In the embodiment, the manufacturer model of the three-dimensional swing mixer is Changsha Miqi QM-QX4L.

[0046] Example 1

[0047] 16 g of diamond particles with a particle size of 120 μm, 4 g of aluminum powder (purity 99 wt%) with a particle size of 70 μm, and 12 g of analytical pure melamine powder are loaded into a three-dimensional swing mixer and ball-milled at a speed of 300 r / min for 24 h. The mass ratio of the total mass of the diamond particles, aluminum powder, and melamine powder to the mass of the grinding balls (the grinding balls are agate balls with a diameter of 6 mm) is 1:20 to obtain a uniform mixed powder.

[0048] The mixed powder is placed in a bearing steel sleeve with a thickness of 3 mm, an inner diameter of 2 cm, and a height of 5 cm. The two ends of the bearing steel sleeve are sealed with stainless steel gaskets, and then the stainless steel gaskets are clamped with a tiger clamp (the opening is greater than 7.5 cm and the edge wrapping length is 2.5 cm), and then placed in a high-temperature furnace for heat treatment. Argon with a purity of 99% is introduced for protection, and the flow rate of argon is 100 ppm; the heat treatment process is: first heated to 550 °C at a heating rate of 20 °C / min and held for 1 h, and then heated to 900 °C at a heating rate of 20 °C / min and held for 1 h. After the heat treatment is completed, it is naturally cooled to room temperature, the tiger clamp is taken out, and the diamond particles coated with aluminum nitride / aluminum carbide coating are separated by a 130-mesh sieve.

[0049] Example 2

[0050] 18 g of diamond particles with a particle size of 300 μm, 14 g of aluminum powder (purity 99 wt%) with a particle size of 50 μm, and 28 g of analytical pure melamine powder are loaded into a three-dimensional swing mixer and ball-milled at a speed of 200 r / min for 25 h. The mass ratio of the total mass of the diamond particles, aluminum powder, and melamine powder to the mass of the grinding balls (the grinding balls are agate balls with a diameter of 10 mm) is 1:10 to obtain a uniform mixed powder.

[0051] Put the mixed powder into a bearing steel sleeve with a thickness of 4 mm, an inner diameter of 3 cm, and a height of 4 cm. Seal both ends of the bearing steel sleeve with stainless steel gaskets, and then clamp the stainless steel gaskets with a tiger clamp (the opening is greater than 6 cm and the edge wrapping length is 3.5 cm). Place it in a high-temperature furnace for heat treatment, and introduce nitrogen with a purity of 99.9% for protection. The flow rate of nitrogen is 50 ppm. The heat treatment process is as follows: First, heat up to 550 °C at a heating rate of 18 °C / min and hold for 2 h, and then heat up to 1000 °C at a heating rate of 20 °C / min and hold for 1 h. After the heat treatment is completed, cool it naturally to room temperature, take out the tiger clamp, and sieve out the diamond particles coated with aluminum nitride / aluminum carbide coating with a 50-mesh sieve.

[0052] Figure 2 XRD pattern of the diamond particles coated with aluminum nitride / aluminum carbide coating for Example 1; Figure 3 SEM image of the diamond particles coated with aluminum nitride / aluminum carbide coating for Example 1; Figure 4 SEM image of the diamond particles coated with aluminum nitride / aluminum carbide coating for Example 2.

[0053] From Figure 2 It can be seen that aluminum nitride and aluminum carbide have clear and sharp diffraction peaks, indicating that the aluminum nitride / aluminum carbide coating has a high degree of crystallinity. And coatings with a high degree of crystallinity usually have better chemical stability and mechanical properties, which can effectively protect the diamond particles. From Figure 3 And Figure 4 In the SEM images, it can be seen that the surface of the coating is uniform and dense, without obvious holes or defects, indicating that the preparation method of the present invention can effectively achieve uniform coverage of the coating. Such a uniform and dense coating can effectively prevent adverse reactions such as oxidation and graphitization of diamond particles during high-temperature sintering or use.

[0054] Example 3

[0055] Put 15 g of diamond particles with a particle size of 50 μm, 2 g of aluminum powder with a particle size of 80 μm (purity 99 wt%), and 8 g of analytical pure melamine powder into a three-dimensional swing mixer, and ball mill for 24 h at a rotation speed of 300 r / min. The mass ratio of the total mass of diamond particles, aluminum powder, and melamine powder to the mass of the grinding balls (the grinding balls are stainless steel balls with a diameter of 6 mm) is 1:20 to obtain a uniform mixed powder.

[0056] Put the mixed powder into a bearing steel sleeve with a thickness of 3 mm, an inner diameter of 2.5 cm, and a height of 3 cm. Seal both ends of the bearing steel sleeve with stainless steel gaskets, and then clamp the stainless steel gaskets with a tiger clamp (the opening is greater than 4.5 cm and the edge wrapping length is 3 cm). Place it in a high-temperature furnace for heat treatment, and introduce argon with a purity of 99.9% for protection. The flow rate of argon is 50 ppm. The heat treatment process is as follows: First, heat up to 600 °C at a heating rate of 20 °C / min and hold for 1 h, and then heat up to 950 °C at a heating rate of 20 °C / min and hold for 1 h. After the heat treatment is completed, cool it naturally to room temperature, take out the tiger clamp, and screen out the diamond particles coated with aluminum nitride / aluminum carbide coating with a 325-mesh sieve.

[0057] Example 4

[0058] Put 14 g of diamond particles with a particle size of 200 μm, 6 g of aluminum powder (purity 99 wt%) with a particle size of 100 μm, and 15 g of analytical pure melamine powder into a three-dimensional swing mixer, and ball mill for 23 h at a rotation speed of 200 r / min. The mass ratio of the total mass of diamond particles, aluminum powder, and melamine powder to the mass of grinding balls (the grinding balls are stainless steel balls with a diameter of 10 mm) is 1:15 to obtain a uniform mixed powder.

[0059] Put the mixed powder into a bearing steel sleeve with a thickness of 4 mm, an inner diameter of 4 cm, and a height of 2.5 cm. Seal both ends of the bearing steel sleeve with stainless steel gaskets, and then clamp the stainless steel gaskets with a tiger clamp (the opening is greater than 5 cm and the edge wrapping length is 5 cm). Place it in a high-temperature furnace for heat treatment, and introduce argon with a purity of 99% for protection. The flow rate of argon is 100 ppm. The heat treatment process is as follows: First, heat up to 600 °C at a heating rate of 20 °C / min and hold for 1 h, and then heat up to 1000 °C at a heating rate of 20 °C / min and hold for 2 h. After the heat treatment is completed, cool it naturally to room temperature, take out the tiger clamp, and screen out the diamond particles coated with aluminum nitride / aluminum carbide coating with a 70-mesh sieve.

[0060] The present invention uses a mixed powder of aluminum powder, melamine, and diamond, and quickly coats aluminum nitride / aluminum carbide particles on the surface of diamond particles through high-temperature heat treatment. The method of the present invention not only has simple equipment and convenient process, but also has low raw material cost and broad application prospects.

[0061] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing diamond particles with an aluminum nitride / aluminum carbide coating on the surface, characterized in that, It includes the following steps: 1) Mix diamond particles, aluminum powder and melamine powder to obtain a mixed powder; 2) Place the mixed powder in a closed device to obtain a closed mixed powder; 3) Heat-treat the closed mixed powder under a protective atmosphere to obtain diamond particles with an aluminum nitride / aluminum carbide coating on the surface.

2. The preparation method according to claim 1, wherein, In step 1), the particle size of the diamond particles is 50 - 300 μm, the particle size of the aluminum powder is 50 - 100 μm, and the purity of the aluminum powder is ≥99 wt%.

3. The preparation method according to claim 1 or 2, characterized in that, In step 1), the mass ratio of the aluminum powder to the melamine powder is 1:2 - 4, and the mass fraction of the diamond particles in the mixed powder is 20 - 60%.

4. The preparation method according to claim 3, wherein, In step 1), the rotation speed of the mixing is 200 - 300 r / min, the mixing time is 22 - 26 h, and during the mixing process, the mass ratio of the total mass of the diamond particles, aluminum powder and melamine powder to the mass of the grinding balls is 1:10 - 20.

5. The preparation method according to claim 3, characterized in that, In step 2), the specific process of placing the mixed powder in the closed device is: put the mixed powder into a bearing steel sleeve, seal both ends of the bearing steel sleeve with stainless steel gaskets, and then clamp the stainless steel gaskets with a tiger clamp; The thickness of the bearing steel sleeve is 3 - 4 mm, the length of the bearing steel sleeve is less than 2 / 3 of the opening of the tiger clamp; the outer diameter of the bearing steel sleeve is similar to the wrapping length of the tiger clamp; the thickness of the stainless steel gasket is 2 - 4 mm.

6. The preparation method according to claim 5, characterized in that, In step 3), the protective atmosphere is an argon atmosphere or a nitrogen atmosphere, the purity of the protective atmosphere is 99 - 99.9%, and the flow rate of the protective atmosphere is 50 - 100 ppm.

7. The preparation method according to claim 1 or 6, characterized in that, In step 3), the heat treatment includes a first heat treatment and a second heat treatment. The temperature of the first heat treatment is 550 - 600 °C, and the time of the first heat treatment is 1 - 2 h; the temperature of the second heat treatment is 900 - 1000 °C, and the time of the second heat treatment is 1 - 2 h.

8. The preparation method according to claim 7, characterized in that, In step 3), the heating rate of the heat treatment is 10 - 20 °C / min.

9. Diamond particles with an aluminum nitride / aluminum carbide coating on the surface prepared by the preparation method according to any one of claims 1 - 8.

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