Diamond powder coated with silicon carbide coating on surface as well as preparation method and application of diamond powder

Abstract

The invention relates to the technical field of silicon carbide coating preparation, in particular to diamond powder with the surface coated with a silicon carbide coating and a preparation method and application thereof.The preparation method comprises the steps that S1, silicon source powder, a porous partition plate and the diamond powder are sequentially placed in a container, and the container is sealed; s2, the pressure in the container is adjusted, meanwhile, the temperature in the container is increased, the silicon source powder is heated to be subjected to a chemical reaction, a gaseous silicon source substance is formed, the gaseous silicon source substance reacts with the diamond powder to generate silicon carbide, the silicon carbide is deposited on the diamond powder, and then the silicon carbide is naturally cooled to the room temperature; and S3, the diamond powder is taken out and sequentially subjected to cleaning treatment and drying treatment, and the diamond powder with the surface coated with a silicon carbide coating is obtained. According to the preparation method, the requirement for equipment is relatively low, the preparation cost is relatively low, and large-scale preparation can be achieved; the bonding performance between the silicon carbide coating and the diamond is excellent, the compactness is high, no extra thermal barrier is formed at the interface between the silicon carbide coating and the diamond, and the interface thermal resistance is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon carbide coating preparation, and particularly relates to diamond powder coated with a silicon carbide coating and a preparation method and application thereof. BACKGROUND

[0002] Metal-based diamond powder reinforced composite materials have extremely broad application potential in many high-end fields such as electronic packaging and aerospace thermal management due to their high thermal conductivity, low thermal expansion coefficient and excellent mechanical properties. Among them, aluminum-based diamond composite materials (Al / diamond) have the advantages of low cost and significant lightweight; however, in actual application, aluminum-based diamond composite materials face a serious interface reaction problem; when in a high-temperature state, aluminum (Al) and diamond (C) will chemically react to form brittle aluminum carbide (Al4C3); aluminum carbide is extremely easy to hydrolyze, and its hydrolysis reaction formula is: Al4C3+12H2O→4Al(OH)3+3CH4; this property causes its internal structure to gradually deteriorate in a humid environment, and its thermal conductivity also decays, thereby seriously threatening the long-term thermal stability of the aluminum-based diamond composite material and greatly limiting its application in complex environments. To effectively inhibit the interface reaction in the aluminum-based diamond composite material, a titanium (Ti) or nickel (Ni) metal coating is usually prepared on the surface of the diamond as an intermediate layer by using a magnetron sputtering or chemical plating process; although this method can block the direct contact between aluminum and carbon to some extent, it still has the following significant defects: (1) high interface thermal resistance: the thermal conductivity of the metal coating is much lower than that of diamond (Diamond:>2000W / mK), especially the Ni coating, and this difference will form an additional thermal barrier at the interface, seriously affecting the long-term reliability of the material; (2) during thermal cycling, the elements in the metal coating will diffuse, thereby causing the interface performance to degrade and reducing the overall performance of the composite material; (3) when low-temperature plating is performed based on magnetron sputtering, the adhesion of the metal coating to the diamond substrate is poor. Therefore, it is urgent to develop a new interface regulation strategy.

[0003] In the article “CVD synthesis of nanometer SiC coating on diamond particles” (published in Ceramics International 47 (2021) 16162-16169), it is disclosed in detail how to use the chemical vapor deposition method (CVD) to deposit a continuous and dense nanometer SiC coating on diamond powder; however, this method has high process cost and strict equipment requirements, and cannot be used to prepare a large quantity.

[0004] The application provides a method for preparing a silicon carbide coating on a diamond surface to solve the problems of poor combination between the diamond and the coating, high interface thermal resistance, inability to batch production and high cost in the prior art. SUMMARY

[0005] The application aims to provide a diamond powder coated with a silicon carbide coating and a preparation method and application thereof to solve the problems of poor combination between the diamond and the coating, high interface thermal resistance, high preparation cost and inability to batch production in the prior art.

[0006] The technical scheme of the application is as follows: a preparation method of a diamond powder coated with a silicon carbide coating, comprising the following steps: S1, placing a silicon source powder, a porous partition plate and a diamond powder in a container connected with a vacuum filtration device at an upper end in sequence, then sealing the container to complete assembly; S2, adjusting the pressure inside the container and increasing the temperature inside the container to make the silicon source powder chemically react under heat to form a gaseous silicon source substance, which flows upward and penetrates into the diamond powder under the action of a pressure difference, reacts with the diamond powder to generate silicon carbide and deposit on the diamond powder, and then naturally cooling the temperature inside the container to room temperature after the deposition is completed; S3, taking out the diamond powder and sequentially performing cleaning treatment and drying treatment to obtain the diamond powder coated with the silicon carbide coating.

[0007] Preferably, the silicon source powder at least comprises silicon powder and silicon dioxide powder, and the molar ratio of the silicon powder to the silicon dioxide powder is (1-1.5):1. Preferably, in the deposition process in step S2, the reaction mainly occurring inside the container is Si+SiO2=SiO(g), SiO(g)+2C=SiC(s)+CO(g).

[0008] Preferably, in step S2, the pressure inside the container is adjusted to 10 -5 -10 2 Pa, the temperature inside the container is increased to 1200-1500 DEG C, and the temperature inside the container is uniformly increased.

[0009] Preferably, in step S1, before assembly, the diamond powder is subjected to surface pretreatment to activate the surface of the diamond powder. The surface pretreatment is one or more of plasma cleaning and high-temperature oxidation treatment.

[0010] Preferably, the particle size of the silicon powder and the silicon dioxide powder is not more than 50 mu m. The particle size of the diamond powder is 1-1000 microns.

[0011] Preferably, the porous partition plate is made of any one of graphite, tantalum, tungsten, and ceramic material. The average pore size of the porous partition plate is not more than the particle size of the diamond powder.

[0012] Preferably, in step S3, the cleaning agent used in the cleaning process is alcohol and / or pure water. The processing temperature of the drying process is 50-120 degrees Celsius. The thickness of the silicon carbide coating on the diamond powder coated with the silicon carbide coating is 0.1-5 microns.

[0013] The application also provides a diamond powder coated with a silicon carbide coating, which is prepared by the above preparation method.

[0014] The application also provides the application of the above diamond powder coated with a silicon carbide coating, which includes being used as a raw material to prepare a metal-based diamond composite material.

[0015] Compared with the prior art, the application has the following advantages: (1) The application provides a diamond powder coated with a silicon carbide coating and a preparation method and application thereof. The preparation method is to promote the chemical reaction of the silicon source powder to generate gaseous silicon source substances by heating, drive the gaseous silicon source substances to penetrate into the interior of the diamond powder under the action of the pressure difference, make the gaseous silicon source substances react with the diamond in situ, generate silicon carbide and deposit on the surface of the diamond particles, and effectively improve the bonding performance between the silicon carbide coating and the diamond, thereby significantly enhancing the compactness of the coating. At the same time, the preparation method has relatively low requirements for equipment, the cost of the raw materials used is low, and a large quantity of diamond powder coated with a silicon carbide coating can be prepared, which has extremely high economic benefits. The problems existing in the prior art, such as poor bonding between the diamond and the coating, high preparation cost of the diamond powder coated with a silicon carbide coating, and inability to mass-produce, are solved.

[0016] (2) Since the thermal conductivity of silicon carbide is close to that of diamond, no additional thermal barrier is formed between them at the interface, so that the interfacial thermal resistance of the diamond powder coated with a silicon carbide coating is low, thereby significantly improving the long-term reliability of the metal-based composite material prepared subsequently. At the same time, since silicon carbide has high stability, even at high temperatures, the silicon carbide coating on the surface of the diamond will not have the phenomenon of element diffusion, thereby effectively avoiding the degradation of the interface performance, and thereby helping to improve the overall performance of the metal-based composite material prepared subsequently. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is an assembly diagram for preparing the diamond powder with a silicon carbide coating on its surface, as described in this invention. Figure 2 This is a surface morphology diagram of the diamond powder described in Embodiment 1 of the present invention; Figure 3 This is a surface morphology diagram of the diamond powder with a silicon carbide coating obtained in Embodiment 1 of the present invention; The components include: 1. Silicon source powder; 2. Porous separator plate; 3. Diamond powder; 4. Container; 5. Heating device; 6. Gas outlet. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments: A method for preparing diamond powder with a silicon carbide coating on its surface includes the following steps: S1, such as Figure 1 As shown, silicon source powder 1, porous partition plate 2, and diamond powder 3 are placed sequentially inside container 4. The upper end of container 4 is the gas outlet 6, which is used to connect to the vacuum filtration device. Then, container 4 is sealed to complete the assembly. Before assembly, the diamond powder needs to undergo surface pretreatment to activate its surface, which is more conducive to the deposition of the SiC coating. Surface pretreatment methods can include plasma cleaning, high-temperature oxidation, etc. The particle size of the diamond powder is preferably 1-1000 μm. The silicon source powder includes at least silicon powder and silicon dioxide powder. In the silicon source powder, the molar ratio of silicon powder to silicon dioxide powder is preferably (1-1.5):1. The particle size of silicon powder and silicon dioxide powder is preferably no more than 50 μm, and more preferably 10 μm or less. The porous separator can be made of materials with good high-temperature stability, such as graphite, tantalum, tungsten, or ceramics. The porosity of the porous separator is preferably 35-50%, and the average pore size of the pores on the porous separator should not exceed the particle size of the diamond powder, and is preferably controlled within the range of 0.1-200 μm.

[0019] S2. Adjust the pressure inside the container to 10 from the top using a vacuum filtration device. -5 -10 2Pa; then, the container is heated by the heating device 5, the temperature inside the container is uniformly increased to 1200-1500℃ at a rate of 5-20℃ / min, the silicon source powder is chemically reacted to form gaseous silicon source material; since the upper end of the container is above the diamond powder, i.e. the gas outlet end of the container is above the diamond powder, when the pressure inside the container is adjusted by the vacuum filtration device, a certain pressure difference can be formed inside the container, and then the gaseous silicon source material formed under the action of the pressure difference flows upwards and penetrates into the interior of the diamond powder bed, reacts with the diamond powder particles, and in-situ generates silicon carbide and deposits on the surface of the diamond powder; the temperature is kept for 0.1-5h, so that the gaseous silicon source material is continuously generated and deposited on the diamond powder until the predetermined deposition effect is achieved; then, the temperature inside the container is naturally cooled to room temperature. During the deposition process, the first chemical reaction occurring inside the container is mainly Si+SiO2=SiO(g), and the SiO(g) generated by the reaction is the gaseous silicon source material; the SiO(g) flows upwards through the pores on the porous partition plate, contacts the diamond powder and reacts, the chemical reaction formula is: SiO(g)+2C=SiC(s)+CO(g), and then a dense silicon carbide coating is formed on the surface of the diamond powder.

[0020] S3, after the diamond powder is taken out of the container, it is placed in an ultrasonic cleaning device, and is cleaned with alcohol, pure water or the like as a cleaning agent; then, the diamond powder is placed in a drying device and dried at a temperature of 50-120℃, and finally a diamond powder coated with a silicon carbide coating is obtained. The thickness of the silicon carbide coating is related to the content of the silicon source powder inside the container, the heat preservation time and the like; the content of the silicon source powder, the heat preservation time and the like can be reasonably adjusted to control the thickness of the silicon carbide coating according to the actual use requirements; in the present application, the thickness of the silicon carbide coating is preferably 0.1-5μm.

[0021] This invention also provides diamond powder with a silicon carbide coating prepared by the above-described method and its applications. These applications include using it as a raw material to prepare metal-based diamond composites, such as copper-based diamond composites, aluminum-based diamond composites, etc. When using diamond powder with a silicon carbide coating as a raw material to prepare aluminum-based diamond composites, the silicon carbide coating deposited on the diamond powder surface not only blocks direct contact between aluminum and carbon, preventing a chemical reaction between aluminum (Al) and diamond (C) to form brittle aluminum carbide, but also effectively solves a series of problems caused by the hydrolysis of the brittle aluminum carbide, such as the gradual deterioration of the internal structure of the aluminum-based diamond composite under humid and hot environments and the attenuation of thermal conductivity. Furthermore, since the thermal conductivity of the silicon carbide coating is close to that of diamond, it also avoids the formation of an additional thermal barrier at the interface due to the coating's own thermal conductivity being much lower than that of diamond, thereby significantly improving the long-term reliability of metal-based diamond composites.

[0022] Example 1

[0023] S1. Place 1000g of diamond powder into a pretreatment device and seal the device. Then, introduce argon gas into the pretreatment device to perform plasma cleaning on the diamond powder, thereby activating the surface of the diamond powder and facilitating the deposition of a silicon carbide coating. Figure 2 The image shows the surface morphology of diamond powder after surface pretreatment. Next, 100g of silicon source powder was placed in a container equipped with a vacuum filtration device at the top. A 3mm thick porous separator plate was placed inside the container, positioned above the silicon source powder. The pretreated diamond powder was then placed on the porous separator plate, and the container was sealed to complete the assembly. The silicon source powder consisted of silicon powder and silicon dioxide powder, with a molar ratio of 1:1. The particle size of both silicon powder and silicon dioxide powder was 10μm, and the particle size of the diamond powder was 200μm. The porous separator plate was made of graphite material with good high-temperature stability. The porosity of the porous separator plate was 35%, and the average pore size was approximately 50μm. S2. First, adjust the pressure inside the container to 10Pa using a vacuum filtration device, then raise the temperature inside the container to 1300℃, so that the silicon source powder is heated and sublimated and deposited on the diamond powder. Keep it at this temperature for 0.5h, and then let it cool naturally to room temperature. S3. After removing the diamond powder from the container, place it in an ultrasonic cleaning device. Clean the diamond powder sequentially using alcohol and pure water as cleaning agents. Then, dry it at 80°C. Figure 3 As shown, diamond powder with a silicon carbide coating on the surface was finally obtained, and the thickness of the silicon carbide coating was 1 μm.

[0024] Example 2

[0025] S1, 2000g of diamond powder was placed in an oxidation furnace, the temperature of the oxidation furnace was raised to 600℃, and the diamond powder surface was pretreated at a temperature of 600℃ for 0.5h; then, 180g of silicon source powder was laid in a container provided with a vacuum filtration device at the upper end, a porous partition plate with a thickness of 5mm was placed inside the container and arranged above the silicon source powder, the pretreated diamond powder was laid on the porous partition plate, and then the container was sealed to complete the assembly; wherein the silicon source powder includes silicon powder and silicon dioxide powder, and the molar ratio of the silicon powder to the silicon dioxide powder is 1.2:1; the particle size of the silicon powder and the silicon dioxide powder is 10μm, and the particle size of the diamond powder is 200μm; the porous partition plate is made of graphite material with good high-temperature stability, and the porosity of the porous partition plate is 40%, and the average pore size is about 80μm; S2, first adjust the pressure in the container to 1Pa by the vacuum filtration device, then raise the temperature in the container to 1200℃, so that the silicon source powder is heated to sublimate and deposit on the diamond powder, and keep the temperature for 0.5h, then naturally cool to room temperature; S3, after taking out the diamond powder from the container, place it in an ultrasonic cleaning device, and use alcohol and pure water as cleaning agents in sequence to clean the diamond powder, then dry at a temperature of 80℃, finally get diamond powder coated with silicon carbide coating, and the thickness of the silicon carbide coating is 1μm.

[0026] Example 3

[0027] S1, 1000g of diamond powder was placed in a pretreatment device, and the pretreatment device was sealed, then argon was introduced into the pretreatment device to clean the diamond powder by plasma, so as to activate the surface of the diamond powder and facilitate the deposition of the silicon carbide coating; then, 150g of silicon source powder was laid in a container provided with a vacuum filtration device at the upper end, a porous partition plate with a thickness of 3mm was placed inside the container and arranged above the silicon source powder, the pretreated diamond powder was laid on the porous partition plate, and then the container was sealed to complete the assembly; wherein the silicon source powder includes silicon powder and silicon dioxide powder, and the molar ratio of the silicon powder to the silicon dioxide powder is 1.1:1; the particle size of the silicon powder and the silicon dioxide powder is 10μm, and the particle size of the diamond powder is 100μm; the porous partition plate is made of ceramic material with good high-temperature stability; the porosity of the porous partition plate is 55%, and the average pore size of the pores on the porous partition plate is about 50μm; S2, first adjust the pressure inside the container to 50 Pa by a vacuum filtration device, then increase the temperature inside the container to 1500 DEG C, so that the silicon source powder is heated to sublimate and deposit on the diamond powder, keep warm for 1 h, and then naturally cool to room temperature; S3, after the diamond powder is taken out of the container, it is placed in an ultrasonic cleaning device, and is sequentially cleaned with alcohol and pure water as cleaning agents, and then is dried at a temperature of 100 DEG C, to obtain diamond powder coated with a silicon carbide coating, and the thickness of the silicon carbide coating is 3 microns.

[0028] From Figure 3 It can be seen that in Example 1, the diamond powder coated with a silicon carbide coating is obtained, the coating on the surface of the diamond has excellent compactness, and the bonding force between the silicon carbide coating and the diamond is also strong; in Example 2 and Example 3, the diamond powder coated with a silicon carbide coating is obtained, and the properties are the same as those in Example 1, and also have high compactness and excellent bonding performance. This shows that the preparation method provided by the application can significantly improve the bonding performance and compactness between the silicon carbide coating and the diamond by in-situ growing silicon carbide on the surface of the diamond powder and forming a coating. At the same time, due to the high stability of silicon carbide, the silicon carbide coating on the surface of the diamond will not have the phenomenon of element diffusion even at high temperature, thereby effectively avoiding the degradation of the interface performance, and laying a solid foundation for the significant improvement of the overall performance of the metal matrix composite prepared by using it as a raw material. The thermal conductivity of silicon carbide is close to that of diamond, and no additional thermal barrier will be formed between the two at the interface, thereby significantly improving the long-term reliability of the material. In addition, the preparation method provided by the application has low raw material cost, relatively low requirement for equipment, and can mass-produce diamond powder coated with a silicon carbide coating, and has high economic benefits.

[0029] The above examples are only for illustrating the technical concept and characteristics of the application, and the purpose is to enable those skilled in the art to understand the content of the application and implement it, and cannot limit the protection scope of the application. For those skilled in the art, it is obvious that the application is not limited to the details of the above exemplary embodiments, and the application can be implemented in other specific forms without departing from the spirit or basic characteristics of the application, therefore, from any point of view, the examples should be regarded as exemplary and non-limiting, the scope of the application is defined by the appended claims rather than the above description, therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application.

Claims

1. A method for preparing diamond powder with a silicon carbide coating, characterized in that, Includes the following steps: S1. Place the silicon source powder, porous separator plate, and diamond powder in sequence into a container with a vacuum filtration device connected to the top. Then, seal the container to complete the assembly. S2. Adjust the pressure inside the container and raise the temperature inside the container to make the silicon source powder react chemically and form gaseous silicon source material. Under the action of pressure difference, the gaseous silicon source material flows upward and penetrates into the diamond powder, reacts with the diamond powder to generate silicon carbide and deposits on the diamond powder. After the deposition is completed, the temperature inside the container is naturally cooled to room temperature. S3. Take out the diamond powder and perform cleaning and drying processes in sequence to obtain diamond powder with a silicon carbide coating on the surface.

2. The method for preparing diamond powder with a silicon carbide coating according to claim 1, characterized in that: The silicon source powder includes at least silicon powder and silicon dioxide powder, and the molar ratio of silicon powder to silicon dioxide powder is (1-1.5):

1.

3. The method for preparing diamond powder with a silicon carbide coating according to claim 2, characterized in that: In step S2, during the deposition process, the main reactions occurring inside the container are: Si + SiO2 = SiO(g), SiO(g) + 2C = SiC(s) + CO(g).

4. The method for preparing diamond powder with a silicon carbide coating according to claim 2, characterized in that: In step S2, the pressure inside the container is adjusted to 10. -5 -10 2 Pa; the temperature inside the container rises to 1200℃-1500℃, and the temperature inside the container rises at a uniform rate.

5. The method for preparing diamond powder with a silicon carbide coating according to claim 2, characterized in that: In step S1, before assembly, the diamond powder is pretreated to activate the surface of the diamond powder. The surface pretreatment method is one or more of plasma cleaning and high-temperature oxidation treatment.

6. The method for preparing diamond powder with a silicon carbide coating according to claim 2, characterized in that: The particle size of both the silicon powder and the silicon dioxide powder does not exceed 50 μm; The diamond powder has a particle size of 1~1000μm.

7. The method for preparing diamond powder with a silicon carbide coating according to claim 1, characterized in that: The porous partition plate is made of any one of graphite, tantalum, tungsten, or ceramic materials; The average pore size of the pores on the porous separator plate does not exceed the particle size of the diamond powder.

8. The method for preparing a silicon carbide coating on a diamond surface according to claim 1, characterized in that: In step S3, the cleaning agent used in the cleaning process is alcohol and / or pure water; The drying process is carried out at a temperature of 50-120℃. The thickness of the silicon carbide coating on the diamond powder with the silicon carbide coating on the surface is 0.1-5 μm.

9. A diamond powder with a silicon carbide coating on its surface, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the diamond powder with a silicon carbide coating as described in claim 9, characterized in that, include: It is used as a raw material to prepare metal-based diamond composite materials.

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