Method for preparing metal carbide coating on surface of diamond powder by one-step based on double-target magnetron sputtering technology

Abstract

This invention relates to the field of composite material technology, specifically to a one-step method for preparing a metal carbide coating on the surface of diamond powder using dual-target magnetron sputtering technology. The method includes: pretreating diamond particles to remove surface impurities; loading the pretreated diamond particles into a vacuum rolling deposition apparatus, using a metal target and a graphite target as targets, and directly depositing a metal carbide coating on the surface of the diamond particles via dual-target magnetron sputtering in an argon atmosphere. This method eliminates the need for subsequent high-temperature heat treatment, performing the process near room temperature, thus avoiding thermal damage to the diamond and oxidation of the metal coating. The process is significantly simplified, highly efficient, and easy to implement. By controlling the sputtering parameters, a dense, uniform, high-purity, and controllable thickness metal carbide coating can be obtained on the surface of the diamond particles, effectively optimizing the interface between the diamond and the metal matrix, and laying the foundation for the preparation of high-performance diamond / metal composite materials.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and specifically to a method for preparing a metal carbide coating on the surface of diamond powder in a one-step process based on dual-target magnetron sputtering technology. Background Technology

[0002] Heat sink materials for electronic packaging have undergone three generations of development, but they can no longer meet the ever-increasing heat dissipation requirements of power devices. Heat dissipation has become a technical bottleneck in the development of the electronic information industry. Metal-based diamond composite materials are a new type of heat sink material for electronic packaging, possessing excellent properties such as high thermal conductivity and low coefficient of thermal expansion. As the most promising next-generation heat sink material for electronic packaging, it has become a hot research topic for researchers in this field.

[0003] Significant interfacial compatibility issues often arise during the preparation of diamond / metal composites. Studies have found that coating the surface of diamond powder with a metal carbide coating is an effective way to optimize the interface. On the one hand, the coefficients of thermal expansion of typical carbide coatings (such as ZrC, TiC, Cr7C3 / Cr3C2, WC / W2C, Mo2C, etc.) can form an appropriate gradient with those of diamond and metal, reducing residual stress at the interface. On the other hand, the carbide coating can block interfacial reactions between diamond and metal, promote wetting and bonding between diamond and metal, and inhibit thermal damage (graphitization transformation) of diamond particles.

[0004] Currently, methods for coating diamond powder with metal carbides mainly include molten salt deposition, magnetron sputtering, and vacuum micro-evaporation deposition. Among these, molten salt deposition produces coatings that are uneven, have numerous defects, and yield impure diamond powder. Vacuum micro-evaporation deposition involves extremely high temperatures that can damage the diamond structure, leading to thermal damage. In contrast, magnetron sputtering is a room-temperature coating method that does not damage the diamond structure during deposition, and produces dense, uniform, and highly pure coatings with controllable thickness. Numerous studies have proposed using magnetron sputtering technology to modify the surface of diamond powder, aiming to address the interfacial compatibility issues between diamond and metal. Zhang Hailong et al. proposed using magnetron sputtering to deposit a Zr coating on the surface of diamond, followed by heat treatment to form ZrC, thereby improving interfacial bonding (CN108707770B); Xie Zhongnan et al. used magnetron sputtering to deposit a mixed coating composed of carbide-forming elements (Ti, Zr, W, Cr, B) and active metal elements (Zn, Al, Fe, Cu, Ni) on the surface of diamond, and obtained a carbide interface layer with an irregular structure through high-temperature heat treatment and etching to reduce the interfacial thermal resistance between diamond and metal (CN113548909B); Xu et al. used magnetron sputtering to deposit a Ti coating on the surface of diamond particles, and at a vacuum annealing temperature of 1000 °C, the Ti coating completely reacted with the diamond to transform into a TiC coating (X. Xu, B. Wan, W. Li, et al. Reactionmechanisms for Ti coatings on diamond. Carbon, 2024, 226: (119206); Zhu et al. deposited a tungsten coating on the surface of diamond particles using magnetron sputtering and formed a WC coating in situ on the diamond surface at a vacuum annealing temperature of 900 °C (P. Zhu, Q. Zhang, S. Qu., et al. Effect of interface structure on thermal conductivity and stability of diamond / aluminum composites. Composites Part A, 2022, 162: 107161). In order to form a carbide coating on the surface of diamond particles, the above-mentioned series of modification techniques all involve magnetron sputtering coating and subsequent vacuum annealing heat treatment. In addition, Wang Changrui et al. prepared metal coatings (W, Ti, Zr, Mo, etc.) on the surface of diamond powder using magnetron sputtering, and then promoted the transformation of metal modification elements on the surface of diamond particles to carbides through solid carburizing or salt bath carburizing treatment (CN118726926B).It can be seen that existing technologies often require two stages to complete the preparation of the metal carbide film on the diamond surface. The process is relatively complex, and the annealing or carburizing temperature is high (800~1300 ℃) and the equipment vacuum degree requirement is high (about 10). -4 When the high-temperature processing time is not well controlled, or when the equipment vacuum level is low and cannot provide good protection for the diamond, prominent problems such as oxidation of the pure metal film on the diamond surface and damage to the diamond structure (graphitization) are likely to occur. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a one-step method for preparing a metal carbide coating on the surface of diamond powder based on dual-target magnetron sputtering technology, as well as the modified diamond particles obtained therefrom. This process is simple, efficient, and easy to implement, requiring no subsequent vacuum heat treatment or carburizing treatment. The diamond powder is not thermally damaged, and the film is dense, uniform, highly pure, free from oxidation, and its thickness can be precisely controlled.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for preparing a metal carbide coating on the surface of diamond powder in one step using dual-target magnetron sputtering technology, characterized by comprising the following steps: S1. Pre-treat the diamond particles to remove surface impurities; S2. Pretreated diamond particles are loaded into a vacuum rolling coating apparatus, and a metal target and a graphite target are used as target materials. Metal carbide coatings are obtained by dual-target magnetron sputtering deposition in an argon atmosphere.

[0007] Further, in S1, the pretreatment is: acid washing or alkali washing of the diamond particles; Furthermore, in S1, the diamond particles have a particle size of 40~200μm.

[0008] Furthermore, in S2, the metal target material is one of Zr, Ti, Cr, W, or Mo.

[0009] Further, in S2, the thickness of the metal carbide coating is 50-200 nm, or 50-180 nm, or 50-150 nm, or 80-150 nm, or 80-120 nm, or 80-100 nm.

[0010] Furthermore, in S2, the argon gas purity is 99.99% and the argon gas flow rate is 10~30 sccm.

[0011] Furthermore, in S2, the sputtering pressure is 0.5~2.5 Pa, and the sputtering time is 30~90 min.

[0012] Furthermore, during the dual-target magnetron sputtering deposition process, the rotation speed of the vacuum rolling coating equipment is 10-30 r / min.

[0013] Furthermore, in S2, the graphite target adopts a DC magnetron sputtering mode with a power of 200~300 W.

[0014] Furthermore, in S2, the metal target adopts a DC magnetron sputtering mode with a power of 300~400 W.

[0015] Secondly, the present invention provides a modified diamond particle prepared by the above method, wherein a metal carbide coating is formed on the surface of the diamond particle, the coating being one of ZrC, TiC, Cr7C3 / Cr3C2, WC / W2C or Mo2C, and the coating thickness is 80-100 nm.

[0016] The method of this invention uses a metal target and a graphite target as dual targets to directly deposit a metal carbide coating on the surface of diamond particles via one-step magnetron sputtering in an argon atmosphere, eliminating the need for subsequent high-temperature heat treatment or carburizing processes required in existing technologies. This process is carried out near room temperature, fundamentally avoiding thermal damage to the diamond structure and oxidation of the pure metal coating at high temperatures that may be caused by high-temperature treatment. Simultaneously, the one-step process significantly simplifies the flow, making it highly efficient and easy to implement. By controlling the sputtering parameters, a dense, uniform, high-purity, and controllable-thickness metal carbide coating can be obtained on the surface of diamond particles, effectively optimizing the interface between diamond and the metal matrix and laying the foundation for the preparation of high-performance diamond / metal composite materials. Attached Figure Description

[0017] Figure 1 These are the morphology characterization diagram and EDS energy spectrum diagram of the initial diamond particles of the present invention; wherein, 1a is the SEM image of the diamond particles; 1b is the carbon element distribution diagram in 1a; 1c is the EDS image of the diamond particles; Figure 2 These are morphology characterization images and EDS energy dispersive spectroscopy (EDS) images of the ZrC-coated diamond particles of the present invention; wherein, 2a is a SEM image of the ZrC-coated diamond particles; 2b is a zirconium element distribution diagram in 2a; and 2c is an EDS image of the ZrC-coated diamond particles. Figure 3 The image shows the XRD pattern of the ZrC-coated diamond particles of this invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise specified, the test materials used in the following embodiments were purchased from conventional biochemical reagent stores. Unless otherwise stated, percentages and parts are by weight. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar with the art. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] Diamond / metal composites, as a new generation of high-performance electronic packaging heat sink materials, rely on optimizing the interface between diamond and the metal substrate for optimal performance. Existing technologies typically employ a two-step method to prepare the metal carbide interface layer, first by sputtering a pure metal coating and then by high-temperature heat treatment or carburizing. This method is complex, and the high-temperature process can easily lead to thermal damage to the diamond or oxidation of the coating.

[0021] This invention utilizes a metal target and a graphite target as co-sputtering sources. In an argon atmosphere, metal and carbon atoms are simultaneously sputtered and deposited onto the surface of continuously rolling diamond particles, directly combining to form the desired metal carbide coating. This process is carried out near room temperature, eliminating the need for subsequent high-temperature treatment. This fundamentally avoids the risks of diamond structure damage and pure metal coating oxidation caused by high temperatures, significantly simplifying the process and resulting in a dense, uniform coating with controllable purity.

[0022] Based on the present invention, a method for preparing a metal carbide coating on the surface of diamond powder using a one-step method based on dual-target magnetron sputtering technology is provided, comprising the following steps: S1. Pre-treat the diamond particles to remove surface impurities; In some embodiments of this implementation, the pretreatment can be acid washing or alkaline washing. For example, hydrofluoric acid solution can be used for acid washing, or sodium hydroxide solution can be used for alkaline washing to remove organic contaminants, oxides, or other impurities that may be attached to the surface, ensuring good adhesion between the subsequent coating and the diamond substrate; the object of the pretreatment, i.e., the diamond particles, preferably has a particle size of 40~200μm. Diamond particles in this particle size range have a suitable specific surface area, which is beneficial to the uniform deposition of the coating and also facilitates ideal filling and distribution in the composite material; S2. Pretreated diamond particles are loaded into a vacuum rolling coating apparatus, and a metal target and a graphite target are used as target materials. Metal carbide coatings are obtained by dual-target magnetron sputtering deposition in an argon atmosphere.

[0023] In some embodiments of this implementation, the metal target used can be selected from Zr, Ti, Cr, W, or Mo. Correspondingly, the final metal carbide coating formed on the surface of the diamond particles is ZrC, TiC, Cr7C3 / Cr3C2, WC / W2C, or Mo2C. By selecting different metal target materials, various carbide coatings can be flexibly prepared to meet the interface matching requirements of different metal substrates. In some embodiments of this implementation, the sputtering pressure is 0.5~2.5 Pa; the sputtering pressure can be selected as 0.5 Pa, 1 Pa, 1.5 Pa, 2 Pa, or 2.5 Pa; other specific values ​​within this range are also acceptable and will not be elaborated here. The sputtering time is 30~90 min; the sputtering time can be selected as 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, or 90 min; other specific values ​​within this range are also acceptable and will not be elaborated here. By controlling parameters such as sputtering time, the thickness of the formed metal carbide coating can be controlled within the range of 50-200 nm. This thickness range can effectively utilize the interface optimization effect of the carbide coating; too thin a coating may not be effective enough, while too thick a coating may introduce new interface stresses. In some embodiments of this implementation, the purity of the argon gas used is preferably 99.99% to minimize the interference of impurity gases on the deposition process. The argon gas flow rate is controlled between 10 and 30 sccm; it can be selected as 10 sccm, 15 sccm, 20 sccm, 25 sccm, or 30 sccm; other specific values ​​within this range are also acceptable and will not be elaborated here. Within this range, the argon gas can be effectively ionized to generate plasma, while ensuring that the sputtered target particles have sufficient energy and an appropriate mean free path to reach the diamond surface and form a dense coating.

[0024] In some embodiments of this implementation, to ensure that each surface of the diamond particles receives the particle stream from the target material uniformly, the roller speed of the vacuum tumbling coating equipment is controlled at 10-30 r / min during the dual-target magnetron sputtering deposition process. This continuous tumbling motion ensures a three-dimensional uniform coating coverage on the particle surface.

[0025] In some embodiments of this implementation, both the graphite target and the metal target employ DC magnetron sputtering, with the graphite target sputtering power being 200-300 W and the metal target sputtering power being 300-400 W. These two power parameters together determine the sputtering rates of carbon and metal atoms from their respective target surfaces. By adjusting the power ratio between the two, the atomic ratio of metal to carbon in the deposited coating can be precisely controlled, thereby directly obtaining a metal carbide phase with a near-accurate stoichiometric ratio and avoiding the formation of free metal or excessive amorphous carbon.

[0026] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0027] Example 1

[0028] S1. The diamond particles are pretreated by acid washing with hydrofluoric acid solution to remove impurities from the particle surface; S2. Using an ultra-high vacuum powder magnetron sputtering coating system, graphite and Zr targets are respectively mounted on two magnetron target heads. Cleaned diamond powder is placed on a roller within the vacuum chamber. The vacuum chamber cover is closed, and a vacuum is evacuated to a degree less than 5.0 × 10⁻⁶. -4 Pa, then Ar is introduced at a flow rate of 20 sccm, sputtering pressure is 1.0 Pa, both targets are selected in DC magnetron sputtering mode, the power supply for graphite target is 300 W, the power supply for Zr target is 400 W, the drum is turned on, the drum speed is controlled at 10-30 r / min, the sputtering time is 60 min, and diamond powder with ZrC coating is obtained, with a coating thickness of about 80~100 nm.

[0029] Example 2

[0030] S1. The diamond particles are pretreated by acid washing with hydrofluoric acid solution to remove impurities from the particle surface; S2. Using an ultra-high vacuum powder magnetron sputtering coating system, graphite and Ti targets were mounted on two separate magnetron sputtering heads. Cleaned diamond powder was placed on a drum within the vacuum chamber. The vacuum chamber cover was closed, a vacuum was drawn, and Ar was introduced at a flow rate of 20 sccm. The sputtering pressure was 1.0 Pa. Both targets were selected in DC magnetron sputtering mode. The power supply for the graphite target was 300 W, and for the Ti target, it was 400 W. The sputtering time was 60 min, and the drum was turned on. A diamond powder with a TiC surface coating was obtained, with a coating thickness of approximately 80–100 nm.

[0031] Example 3

[0032] S1. The diamond particles are pretreated by acid washing with hydrofluoric acid solution to remove impurities from the particle surface; S2. Using an ultra-high vacuum powder magnetron sputtering coating system, graphite and Mo targets were respectively mounted on two magnetron sputtering heads. Cleaned diamond powder was placed on a drum within the vacuum chamber. The vacuum chamber cover was closed, a vacuum was drawn, and Ar was introduced at a flow rate of 20 sccm. The sputtering pressure was 1.0 Pa. Both targets were selected in DC magnetron sputtering mode. The power supply for the graphite target was 300 W, and the power supply for the Mo target was 400 W. The sputtering time was 60 min, and the drum was turned on. A diamond powder with a surface coating of Mo2C was obtained, with a coating thickness of approximately 80–100 nm.

[0033] Comparative Example 1 S1. The diamond particles are pretreated by acid washing with hydrofluoric acid solution to remove impurities from the particle surface; S2. Pure metallic zirconium was deposited on the surface of cleaned diamond powder using DC magnetron sputtering technology. The sputtering pressure was 1.0 Pa, the power supply for the zirconium target was 400 W, and the sputtering time was 60 min. Then, the zirconium-coated diamond powder was annealed in a vacuum heat treatment furnace at a vacuum level of 1×10⁻⁶. -4 The annealing temperature was 1050 °C, and the annealing time was 90 min. Diamond powder with a ZrC surface coating was obtained, with a coating thickness of approximately 130~150 nm.

[0034] Comparative Example 2 A conventional method for preparing a metal carbide coating on the surface of diamond powder is as follows: First, pure metallic zirconium is deposited on the surface of cleaned diamond powder using DC magnetron sputtering technology. The sputtering pressure is 1.0 Pa, the power supply corresponding to the zirconium target is 400 W, and the sputtering time is 60 min. Then, a mixed salt of NaCl and KCl (molar ratio of 1:1) is heated to 800 °C in a molten state, and zirconium-coated diamond powder and liquid carburizing agent (NaCl, KCl, Na2CO3, and (NH2)2CO are fully dissolved in boiling water, carbon powder is added and stirred evenly, and the mixture is heated to 900 °C in a muffle furnace and held for 24 h. After air cooling to room temperature, the liquid carburizing agent is obtained. The temperature is raised to 900 °C and held for 5 h. After cooling to room temperature, the mixture is washed with water, filtered, and dried to obtain diamond powder treated with salt bath carburizing.

[0035] The degree of oxidation and thermal damage of the diamond-coated particles in the above embodiments and comparative examples were tested, and the results are shown in the table below.

[0036] Degree of oxidation of coating: XRD pattern of diamond powder is obtained by X-ray diffraction, which can be used to analyze whether the coating contains obvious metal oxide phase, so as to determine the degree of oxidation of the coating.

[0037] Degree of thermal damage to diamond: Raman spectroscopy was used to obtain the Raman curve of diamond powder, and the intensity of the characteristic peaks of diamond and graphite could be obtained from the curve, which were labeled as I. G and I D Using formula (I) G / I G +I D ) Calculate the degree of thermal damage to the diamond.

[0038]

[0039] As shown in the table above, the modified diamond particles prepared using the one-step method of this invention (Examples 1-3) showed no oxidation on their surface coatings, and the diamond matrix did not undergo graphitization. In contrast, the two-step method (Comparative Example 1) using a metal layer followed by high-temperature heat treatment resulted in a certain degree of graphitization in the diamond (graphitization degree 10), although the coating did not oxidize. The method (Comparative Example 2) using a metal layer followed by salt bath carburizing resulted in severe oxidation of the metal coating due to the process environment, generating ZrO2, even though the diamond did not graphitize at the carburizing temperature. This demonstrates that the one-step dual-target magnetron sputtering technology provided by this invention can directly obtain high-quality, oxidation-free, and non-damaging metal carbide coatings for the diamond matrix without introducing high-temperature steps, effectively solving the key problems of complex processes and susceptibility to thermal damage or oxidation in existing technologies.

[0040] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Those skilled in the art, under the guidance of the present invention, can make various similar representations without departing from the spirit and claims of the present invention, and such modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing a metal carbide coating on the surface of diamond powder in a one-step process based on dual-target magnetron sputtering technology, characterized in that, Includes the following steps: S1. Pre-treat the diamond particles to remove surface impurities; S2. Pretreated diamond particles are loaded into a vacuum rolling coating apparatus, and a metal target and a graphite target are used as target materials. Metal carbide coatings are obtained by dual-target magnetron sputtering deposition in an argon atmosphere.

2. The method according to claim 1, characterized in that, In step S1, the pretreatment involves: acid washing or alkali washing of the diamond particles; and / or, The diamond particles have a particle size of 40~200μm.

3. The method according to claim 1, characterized in that, In step S2, the metal target material is one of Zr, Ti, Cr, W, or Mo.

4. The method according to claim 1, characterized in that, In step S2, the thickness of the metal carbide coating is 50-200 nm, or 50-180 nm, or 50-150 nm, or 80-150 nm, or 80-120 nm, or 80-100 nm.

5. The method according to claim 1, characterized in that, In S2, the argon gas purity is 99.99% and the argon gas flow rate is 10~30 sccm.

6. The method according to claim 1, characterized in that, In S2, the sputtering pressure is 0.5~2.5 Pa and the sputtering time is 30~90 min.

7. The method according to claim 1, characterized in that, During the dual-target magnetron sputtering deposition process, the rotation speed of the vacuum rolling coating equipment is 10-30 r / min.

8. The method according to claim 1, characterized in that, In S2, the graphite target adopts DC magnetron sputtering mode with a power of 200~300 W.

9. The method according to claim 1, characterized in that, In S2, the metal target is sputtered using a DC magnetron sputtering mode with a power of 300~400 W.

10. A modified diamond particle obtained by the method according to claims 1-9.

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