Silicon carbide template induced coal-based diamond / silicon carbide coating and composite and method of making

Abstract

The present invention discloses a silicon carbide template-induced coal-based diamond / silicon carbide coating and composite material and a preparation method thereof. Low-cost coal / nano-silicon powder is used as a carbon source and a silicon source, and a coal / nano-silicon coating is first formed by ball milling, spin coating, etc., and a layer of quartz glass is covered on the surface of the coal / nano-silicon coating. A high-pulse energy laser is passed through the quartz glass to irradiate the coal / nano-silicon coating, and a carbon thermal reduction reaction occurs to generate silicon carbide with a tetrahedral structure as a template, thereby inducing carbon to form a diamond with a tetrahedral structure, which is converted into a diamond / silicon carbide coating. Another layer of coal / nano-silicon coating is formed on the surface of the diamond / silicon carbide coating, and a high-pulse energy laser is passed through the quartz glass to irradiate the coal / nano-silicon coating again. After multiple cycles, the coating is stacked and additively manufactured to form a diamond / silicon carbide composite material. This method has lower costs, and silicon carbide and diamond are chemically connected through carbon-silicon bonds, and have excellent mechanical properties and thermal conductivity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high-performance superhard material processing and forming, in particular to the preparation method of coal-based diamond / silicon carbide coating and composite material. BACKGROUND

[0002] Diamond is the hardest material known in nature, and its thermal conductivity is the highest among known materials. It is also a wide-bandgap material and an electrical insulator, with excellent corrosion resistance. Silicon carbide has a low thermal expansion coefficient, excellent thermal conductivity, high elastic modulus, and high dimensional stability. Combining diamond and silicon carbide results in a diamond / silicon carbide composite material with ultra-high hardness and specific stiffness, as well as excellent thermal stability and wear resistance. It is expected to be used as a measuring gauge, precision bearing, and mechanical seal component material in the precision instrument field, as an electronic packaging material in the thermal management field, and as a semiconductor wafer chuck, high-stability optical substrate, and high-speed laser scanning mirror for high-power lasers in the optical component field.

[0003] Currently, diamond / silicon carbide composite materials are mostly prepared by converting diamond micro-powder (carbon source) and silicon powder (or polycarbosilane as a silicon source) into diamond / silicon carbide composite materials under certain temperature and pressure. Chinese invention patent CN110698202B "Diamond-silicon carbide composite material and its preparation method and application" proposes a two-step method for preparing diamond-silicon carbide composite material, which uses diamond, silicon powder, graphite, and a binder as raw materials. First, selective sintering is achieved under laser irradiation, and then further silicon infiltration is performed to fully react and convert the residual graphitized carbon structure into silicon carbide. However, this method uses diamond raw materials, which cannot form effective chemical bonds with silicon carbide due to a certain distance between them, affecting the improvement of the thermal conductivity and mechanical properties of the composite material. In addition, if large-size diamond / silicon carbide composite materials are to be prepared, a large amount of diamond raw materials needs to be invested, resulting in high process cost. SUMMARY

[0004] To achieve the formation of chemical bonds between the two phases in the diamond / silicon carbide coating and composite material, the present application proposes a silicon carbide template-induced coal-based diamond / silicon carbide coating and composite material preparation method. High-energy plasma is induced on the surface of coal / silicon powder by laser irradiation, and carbon thermal reduction reaction occurs under thermal shock to generate silicon carbide. Silicon carbide has a tetrahedral structure similar to that of diamond, and carbon atoms will further transform into tetrahedral diamond structure under the action of silicon carbide template under thermal shock. After transformation, silicon carbide and diamond are connected through carbon-silicon bond chemical action, with excellent performance.

[0005] The preparation method of the diamond / silicon carbide coating of the present application is as follows:

[0006] The first step is to mix super-pure coal, nano-silicon powder and isopropyl alcohol by ball milling, and to obtain nano-super-pure coal / nano-silicon mixed powder by drying;

[0007] The second step is to add isopropyl alcohol to the nano-super-pure coal / nano-silicon mixed powder according to a certain ratio, and to obtain a coal / nano-silicon dispersion liquid by magnetic stirring;

[0008] The third step is to prepare a coal / nano-silicon coating on the surface of a flat metal, glass, ceramic or other material workpiece or substrate by spin coating, flow casting or coating method using the obtained nano-super-pure coal / nano-silicon / isopropyl alcohol dispersion liquid.

[0009] The fourth step is to cover a layer of plated quartz glass on the surface of the coal / nano-silicon coating after drying, and to irradiate the coal / nano-silicon coating through the plated quartz glass by using a large pulse energy infrared nanosecond laser, and to convert it into a diamond / silicon carbide coating after moving the irradiation.

[0010] The preparation method of the silicon carbide template induced coal-based diamond / silicon carbide coating and composite material is as follows:

[0011] The first step is to mix super-pure coal, nano-silicon powder and isopropyl alcohol by ball milling, and to obtain nano-super-pure coal / nano-silicon mixed powder by drying;

[0012] The second step is to add isopropyl alcohol to the nano-super-pure coal / nano-silicon mixed powder according to a certain ratio, and to obtain a coal / nano-silicon dispersion liquid by magnetic stirring;

[0013] The third step is to prepare a coal / nano-silicon coating on the surface of a flat metal, glass, ceramic or other material workpiece or substrate by spin coating, flow casting or coating method using the obtained nano-super-pure coal / nano-silicon / isopropyl alcohol dispersion liquid.

[0014] The fourth step is to cover a layer of plated quartz glass on the surface of the coal / nano-silicon coating after drying, and to irradiate the coal / nano-silicon coating through the plated quartz glass by using a large pulse energy infrared nanosecond laser, and to convert it into a diamond / silicon carbide coating after moving the irradiation.

[0015] The fifth step is to prepare a coal / nano-silicon coating on the surface of the diamond / silicon carbide coating again by spin coating, to cover a layer of plated quartz glass on the surface of the coal / nano-silicon coating, and to irradiate the coal / nano-silicon coating through the plated quartz glass by using a large pulse energy infrared nanosecond laser, and to convert it into a diamond / silicon carbide coating after moving the irradiation, and to repeat the fifth step operation, so that the layers can be stacked and connected by chemical bonds between each layer under laser thermal shock, and finally a diamond / silicon carbide composite material with a certain thickness is obtained.

[0016] The beneficial effects of the present application are:

[0017] (1) Coal and nano-silicon are used as carbon source and silicon source, which are rapidly converted into silicon carbide structure under the action of laser-induced plasma, and then used as a template for coal-based diamond, which imitates the growth of tetrahedral structure and is converted into diamond structure in large quantities, and the silicon carbide plays a seed crystal role, which can replace the high-cost diamond seed crystal and play a role in diamond material production;

[0018] (2) The silicon carbide generated by coal and nano-silicon under the action of laser-induced plasma is connected between the silicon carbide and the diamond through carbon-silicon covalent bond, and the diamond / silicon carbide coating is stacked layer by layer to form a diamond / silicon carbide composite material, and the chemical bond between the layers can be formed under the action of heat, so that the mechanical properties, thermal conductivity and other properties of the diamond / silicon carbide coating and the composite material can be enhanced;

[0019] (3) By designing and optimizing the shape and size of each layer, the diamond / silicon carbide coating is stacked layer by layer to additively manufacture a three-dimensional product of diamond / silicon carbide composite material, which can break through the structural limitations of the forming die and realize efficient manufacturing of high-performance diamond / silicon carbide composite material products. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1 Flow chart for preparation method of coal-based diamond / silicon carbide coating induced by silicon carbide template;

[0022] Figure 2 Flow chart for preparation method of coal-based diamond / silicon carbide composite material induced by silicon carbide template. DETAILED DESCRIPTION

[0023] The silicon carbide template induced coal-based diamond / silicon carbide coating and composite material and the preparation method thereof, the preparation method of the silicon carbide template induced coal-based diamond / silicon carbide coating is as follows:

[0024] First step: Put the ultrapure coal (purity more than 99wt%), nano-silicon powder (particle size of 5-30nm), isopropyl alcohol and steel balls (diameter of 3-6mm) into a ball mill according to a certain ratio (mass ratio of (10-14):1:(12-14):(35-38)), and mill at a speed of 350-400 revolutions per minute for 24 hours, and then treat in a vacuum drying box at 100℃ for 5-6 hours, and then dry to obtain nano-sized ultrapure coal / nano-silicon mixed powder;

[0025] Second step: add nano-scale super-pure coal / nano-silicon mixed powder into isopropyl alcohol according to certain proportion (the mass ratio of nano-scale super-pure coal / nano-silicon mixed powder to isopropyl alcohol is 1:(4-5)); through magnetic stirring, a dispersion liquid with the mass fraction of 16.6%-20.0% of nano-scale super-pure coal / nano-silicon mixed powder is obtained;

[0026] Third step: a coal / nano-silicon coating layer is prepared on the surface of a flat metal, glass, ceramic or other material workpiece or substrate through spin coating, flow coating or coating method by using the obtained nano-scale super-pure coal / nano-silicon / isopropyl alcohol dispersion liquid; for example, the spin coating speed is 500 rpm for 10 s and 2000 rpm for 20 s, and the coating thickness is 0.5-1.0 mm.

[0027] Fourth step: after the coal / nano-silicon coating layer is dried, a plated quartz glass layer (with high infrared light transmittance, the transmittance is more than 99.9%) is covered on the upper surface of the coating layer; a diamond / silicon carbide coating layer is formed on the coal / nano-silicon coating layer by using a large pulse energy infrared nanosecond laser to irradiate the coal / nano-silicon coating layer through the plated quartz glass.

[0028] The carbonized silicon template induced coal-based diamond / silicon carbide coating and composite material and the preparation method thereof; the super-pure coal is low metamorphic degree bituminous coal, such as long flame coal and lignite; and the nano-silicon powder can be single crystal silicon or polycrystalline silicon.

[0029] The carbonized silicon template induced coal-based diamond / silicon carbide coating and composite material and the preparation method thereof; a coal / nano-silicon coating layer can be prepared on the surface of a flat metal, glass, ceramic or other material by using spin coating, flow coating or coating method, and the coal / nano-silicon coating layer can be prepared on a complex surface.

[0030] The carbonized silicon template induced coal-based diamond / silicon carbide coating and composite material and the preparation method thereof; a large pulse energy infrared nanosecond laser is used to irradiate the coal / nano-silicon coating layer through the plated quartz glass; the laser can be moved by using a galvanometer, or the laser irradiation point can be fixed, and the workpiece or substrate to be plated is fixed on a three-dimensional motion platform; the quartz glass is plated on both upper and lower surfaces to achieve super-high transmittance (the transmittance is more than 99.9%) of a certain wave band laser; the thickness of the quartz glass is greater than 2 mm; the single pulse energy of the infrared nanosecond laser is greater than 200 mJ, the pulse width is greater than 10 ns, and the frequency is greater than 10 Hz; the large pulse energy (the pulse energy is higher than 200 mJ) infrared nanosecond solid laser can be replaced by a large pulse energy (the pulse energy is higher than 300 mJ) ultraviolet excimer laser, the pulse width is greater than 10 ns, and the frequency is greater than 10 Hz; the single pulse energy of a picosecond laser is higher than 1 mJ, and the single pulse energy of a femtosecond laser needs to be higher than 100 muJ.

[0031] The silicon carbide template induced coal-based diamond / silicon carbide coating and composite material and the preparation method thereof, the workpiece or the substrate to be plated has a certain hardness and can resist local impact high pressure of 1-20 GPa, and metal materials such as hard alloy can be selected.

[0032] The silicon carbide template induced coal-based diamond / silicon carbide coating and composite material and the preparation method thereof, the preparation method of the silicon carbide template induced coal-based diamond / silicon carbide composite material is as follows:

[0033] First step: the ultrapure coal (purity of 99wt% or more), nanometer silicon powder (particle size of 5-30nm), isopropyl alcohol and steel ball (diameter of 3-6mm) are placed in a ball mill according to a certain ratio (mass ratio of (10-14):1:(12-14):(35-38)), the rotation speed is 350-400r / min, the ball milling time is 24 hours, and the nanometer ultrapure coal / nanometer silicon mixed powder is obtained by drying in a vacuum drying box at 100℃ for 5-6 hours.

[0034] Second step: the nanometer ultrapure coal / nanometer silicon mixed powder is added to isopropyl alcohol according to a certain ratio (mass ratio of nanometer ultrapure coal / nanometer silicon mixed powder to isopropyl alcohol is 1:(4-5)); through magnetic stirring, a dispersion liquid with a mass fraction of 16.6%-20.0% of the nanometer ultrapure coal / nanometer silicon mixed powder is obtained.

[0035] Third step: the obtained nanometer ultrapure coal / nanometer silicon / isopropyl alcohol dispersion liquid is prepared into a coal / nanometer silicon coating on the surface of a flat metal, glass, ceramic or other material workpiece or substrate by spin coating, flow casting or coating method; for example, the spin coating speed is 500r / min for 10s and 2000r / min for 20s, and the coating thickness is 0.5-1.0mm.

[0036] Fourth step: after the coal / nanometer silicon coating is dried, a layer of plated quartz glass (with high infrared light transmittance) is covered on the upper surface of the coal / nanometer silicon coating, a large pulse energy infrared nanosecond laser is used to irradiate the coal / nanometer silicon coating through the plated quartz glass, and the diamond / silicon carbide coating is obtained after moving irradiation.

[0037] Fifth step: a layer of coal / nano-silicon coating is prepared again on the surface of the diamond / silicon carbide coating by spin coating, for example, in a spin coating manner, the spin coating speed is (500 rpm for 10 s, 2000 rpm for 20 s), after the coal / nano-silicon coating is dried, a layer of coated quartz glass (with high infrared light transmittance) is covered on the upper surface thereof, a large-pulse-energy infrared nanosecond laser is used to irradiate the coal / nano-silicon coating through the coated quartz glass, and after moving irradiation, the coal / nano-silicon coating is converted into a diamond / silicon carbide coating, the fifth step is repeated, each layer can be stacked layer by layer and connected through a chemical bond between each layer under laser thermal impact, and finally a diamond / silicon carbide composite material with a certain layer thickness is obtained, for example, 15-20 cycles, a diamond / silicon carbide composite material with a thickness of 10-20 mm can be prepared.

[0038] The above is a specific process of the present application, which is described in combination with the drawings. However, the present application is not limited to the specific process described above, any partial adjustment based on the above-mentioned related process, as long as it is within the scope of the present application, belongs to the present application.

Claims

1. A method for preparing a coal-based diamond / silicon carbide composite material induced by a silicon carbide template, characterized in that: The steps involved are as follows: The first step is to place ultrapure coal, nano-silicon powder, isopropyl alcohol, and steel balls in a ball mill at a mass ratio of (10-14):1:(12-14):(35-38), ball mill and mix, and dry to obtain a nano-grade ultrapure coal / nano-silicon mixed powder; Step 2: Add isopropyl alcohol to the nano-scale ultra-pure coal / nano-silicon mixed powder according to a certain ratio, and obtain a dispersion of the nano-scale ultra-pure coal / nano-silicon mixed powder by magnetic stirring; Step 3: Spin-coating the obtained nano-scale ultrapure coal / nano-silicon / isopropyl alcohol dispersion onto a flat surface of a workpiece or substrate made of metal, glass, ceramic or other materials to form a layer of coal / nano-silicon coating; Step 4: After the coal / nano-silicon coating is dried, a layer of coated quartz glass is covered on its upper surface. A large pulse energy laser is used to emit pulsed laser light through the coated quartz glass and irradiate the coal / nano-silicon coating. After moving irradiation, it is converted into a diamond / silicon carbide coating. Step 5: A layer of coal / nano-silicon coating is spin-coated again on the surface of the diamond / silicon carbide coating. After the coal / nano-silicon coating is dried, a layer of coated quartz glass is covered on its upper surface. A large pulse energy laser is used to irradiate the coal / nano-silicon coating through the coated quartz glass. After mobile irradiation, it is converted into a diamond / silicon carbide coating. The fifth step is repeated, layer by layer, and each layer is connected by chemical bonds under laser thermal shock, and finally a diamond / silicon carbide composite material with a certain layer thickness is obtained.

2. The preparation method according to claim 1, wherein: Ultra-pure coal uses low-metamorphic bituminous coal, including long flame coal, coking coal or gas coal, and the purity of the coal reaches more than 99 wt%. The nano-silicon powder is single crystal silicon or polycrystalline silicon, and the particle size of the nano-silicon powder is 5-30 nm.

3. The preparation method according to claim 1, wherein: A layer of coal / nano-silicon coating is prepared on the surface of a flat workpiece or substrate of metal, glass, ceramic or other materials by spin coating, casting or scraping to prepare the coal / nano-silicon coating on the surface with a coating thickness of 0.5-1.0 mm.

4. The preparation method according to claim 1, wherein: A large pulse energy laser is used to irradiate the coal / nano-silicon coating through the coated quartz glass. The large pulse energy laser is a nanosecond laser, picosecond laser or femtosecond laser. The quartz glass achieves ultra-high transmittance of lasers in a certain wavelength band by coating on both the upper and lower surfaces, with a transmittance exceeding 99.9%. The thickness of the quartz glass is greater than 2mm. When using infrared nanosecond laser, its single pulse energy is greater than 200mJ, the pulse width is greater than 10ns, the frequency is greater than 10Hz, the spot diameter is 20-50μm, and the irradiation is focused. When using ultraviolet nanosecond excimer laser, its single pulse energy is higher than 300mJ, the pulse width is greater than 10ns, the frequency is greater than 10Hz, the picosecond laser single pulse energy is higher than 1mJ, and the femtosecond single pulse energy needs to be higher than 100μJ.

5. The preparation method according to claim 1, wherein: The workpiece or substrate to be plated has a certain hardness and can withstand a local impact high pressure of 1 to 20 GPa.

6. A silicon carbide template-induced coal-based diamond / silicon carbide composite material, characterized in that: The silicon carbide template-induced coal-based diamond / silicon carbide composite material is prepared by the preparation method described in any one of claims 1-5.

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