High-thermal-conductivity copper-based composite material for heat dissipation and preparation method thereof

Abstract

The invention discloses a high-thermal-conductivity copper-based composite material for heat dissipation and a preparation method thereof, and relates to the technical field of composites.The preparation method comprises the steps that graphene-tungsten graded coated diamond reinforced powder and spherical copper powder are mechanically mixed in a planetary ball mill, and uniform composite powder is obtained; and the uniform composite powder is loaded into a mold, curing forming is conducted in a vacuum environment through a spark plasma sintering technology, a diamond-tungsten carbide-tungsten-copper gradient interface structure is generated in situ in the sintering process, and the high-heat-conductivity copper-based composite material for heat dissipation is obtained. According to the invention, high thermal conductivity and low thermal expansion are realized by constructing a gradient interface, the thermal cycle reliability is improved by introducing a flexible layer, and the composite material with highly consistent performance is prepared by combining self-adaptive process regulation and control, so that the technical problems of high interface thermal resistance and unstable performance are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, in particular to a high-thermal-conductivity copper-based composite material for heat dissipation and a preparation method thereof. BACKGROUND

[0002] With the rapid development of science and technology, electronic components and devices are evolving towards high integration, high power density and miniaturization. In this process, if the huge heat generated by the operation of the device cannot be dissipated in time and effectively, the internal temperature of the device will rise sharply, which will not only seriously affect its running speed and stability, but also accelerate the aging of the material and shorten the service life of the device, and even may cause catastrophic thermal failure. Therefore, high-performance electronic packaging heat dissipation materials have become a key link restricting the development of high-end electronic technology. Traditional heat dissipation materials, such as pure copper or pure aluminum, although have good thermal conductivity, their thermal expansion coefficients are significantly higher than those of modern semiconductor chip materials, such as gallium nitride or silicon carbide. When the device switches between working and standby states, the periodic temperature changes cause a huge thermal stress between the packaging material and the chip due to thermal expansion mismatch, and this repeated stress easily leads to reliability problems such as interface delamination and chip cracking. In order to overcome this bottleneck, researchers have begun to explore the use of diamond particles with extremely high thermal conductivity and extremely low thermal expansion coefficient as reinforcing bodies, combined with a high-thermal-conductivity copper matrix, in the hope of preparing a composite heat dissipation material that combines the advantages of both.

[0003] Conventional copper-diamond composite materials have not achieved the expected results in practical applications, and there are insurmountable obstacles in their technical route. The core problem lies in the natural interfacial non-wetting between diamond and the copper matrix. The carbon atoms on the surface of the diamond and the copper atoms lack chemical affinity, and cannot form stable chemical bonds, resulting in extremely weak interfacial bonding between the two. This weakly bonded interface forms a huge barrier, i.e. interfacial thermal resistance, to the effective conduction of heat from the copper matrix to the diamond reinforcement. There are fundamental differences in the thermal conduction mechanisms of the two materials. Copper, as a metal, conducts heat mainly through the movement of free electrons, while diamond, as a non-metallic crystal, relies on lattice vibrations to transfer heat. When these two completely different heat conduction carriers meet at the interface, they will be severely scattered due to the serious mismatch of the phonon spectrum, further exacerbating the interfacial thermal resistance. The combined effects of the above two problems make it impossible for the excellent thermal conductivity of diamond to be fully utilized in the composite material, resulting in the overall thermal conductivity of the material being much lower than expected, and failing to meet the increasingly stringent heat dissipation requirements. SUMMARY

[0004] The present application aims to provide a high-thermal-conductivity copper-based composite material for heat dissipation and a preparation method thereof, which solves the problems in the background art.

[0005] To solve the above technical problems, the application provides a preparation method of a high-thermal-conductivity copper-based composite material for heat dissipation, comprising the following steps:

[0006] The graphene-tungsten hierarchical coated diamond reinforced powder and the spherical copper powder are mechanically mixed in a planetary ball mill to obtain a uniform composite powder; the uniform composite powder is loaded into a mold and solidified and formed by a spark plasma sintering process in a vacuum environment, and a diamond-tungsten carbide-tungsten-copper gradient interface structure is generated in situ during the sintering process to obtain the high-thermal-conductivity copper-based composite material for heat dissipation.

[0007] The preparation of the graphene-tungsten hierarchical coated diamond reinforced powder comprises the following steps:

[0008] The graphene oxide and deionized water are subjected to ultrasonic dispersion treatment to obtain a uniform graphene oxide dispersion liquid; tungsten atom-anchored diamond particles are added to the graphene oxide dispersion liquid and subjected to mechanical stirring to obtain a mixed slurry; the mixed slurry is subjected to freeze-drying to coat the graphene oxide on the surface of the tungsten atom-anchored diamond particles; and the coated powder is subjected to gradient temperature rising heat treatment in a hydrogen / argon mixed atmosphere to obtain the graphene-tungsten hierarchical coated diamond reinforced powder.

[0009] The preparation of the tungsten atom-anchored diamond particles comprises the following steps:

[0010] The diamond single crystal particles are placed in a fluidized bed chemical vapor deposition reactor, argon gas is introduced as a carrier gas and heated under a fluidized state of the bed layer; tungsten hexafluoride and hydrogen gas are introduced as reaction gases to perform a chemical vapor deposition reaction, a metal tungsten layer is coated on the surface of the diamond single crystal particles, and the tungsten atom-anchored diamond particles are obtained.

[0011] Preferably, the volume ratio of the graphene-tungsten hierarchical coated diamond reinforced powder to the spherical copper powder is (55-65):(45-35).

[0012] Preferably, the process parameters of the chemical vapor deposition reaction are as follows: the reaction temperature is 500-600 DEG C, the flow rate of the tungsten hexafluoride gas is 15-25 sccm, the flow rate of the hydrogen gas is 80-120 sccm, the negative pressure is 40-60 Pa, and the deposition time is 100-140 minutes.

[0013] Preferably, the process parameters of the gradient temperature rising heat treatment are as follows: the temperature is raised to 750-850 DEG C at a rate of 8-12 DEG C / minute, and the temperature is kept constant at this temperature for 200-280 minutes.

[0014] Preferably, the process parameters of the spark plasma sintering are as follows: the vacuum degree is better than 5.0 Pa, the axial pressure is 45-55 MPa; the temperature is raised to a peak temperature of 950-1000 DEG C at a rate of 80-120 DEG C / minute; and the pressure is kept constant at the peak temperature for 3-7 minutes.

[0015] Preferably, a silver layer with a thickness of 25-35 nanometers is deposited between the tungsten metal tungsten layer anchoring diamond particles and the spherical copper powder using a magnetron sputtering process to form a gradient interface structure of diamond-tungsten carbide-tungsten-silver-copper.

[0016] Preferably, the process includes a raw material batch characteristic detection step, which uses a laser particle size analyzer to measure the average particle size and specific surface area of ​​each batch of diamond raw materials, and adaptively adjusts subsequent process parameters based on the detection results. The process parameters include: tungsten layer deposition time and graphene oxide addition amount.

[0017] A high thermal conductivity copper-based composite material for heat dissipation is also provided, which is prepared by a method for preparing a high thermal conductivity copper-based composite material for heat dissipation, including:

[0018] Copper substrate;

[0019] And graphene-tungsten hierarchically coated diamond reinforcement distributed in a copper matrix;

[0020] A gradient interface structure of diamond-tungsten carbide-tungsten-copper is formed between the diamond reinforcement and the copper matrix.

[0021] Preferably, the gradient interface structure is a five-layer gradient interface of diamond-tungsten carbide-tungsten-silver-copper.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Through a unique interface structure design, a multi-layered gradient transition zone is constructed between the reinforcement and the metal matrix. This gradient interface achieves a strong metallurgical bond between the reinforcement and the matrix at the atomic scale, effectively solving the problem of incompatibility between their physical and chemical properties. This greatly reduces the interfacial thermal resistance and opens up a smooth and unobstructed high-speed channel for heat transfer, enabling heat to be efficiently conducted from the matrix to the highly thermally conductive reinforcement and dissipated rapidly, thus endowing the composite material with excellent overall thermal conductivity.

[0024] By constructing a three-dimensional network skeleton composed of high-strength, low-expansion reinforcements in the matrix and using a stable gradient interface to firmly bind the skeleton to the metal matrix, the expansion of the matrix under heat is effectively suppressed, resulting in a significant reduction in the overall thermal expansion coefficient of the composite material. This allows for a high degree of matching with semiconductor chip materials, thereby greatly reducing the thermal stress caused by temperature fluctuations during device operation and ensuring the long-term reliability of electronic devices.

[0025] By introducing a special flexible functional layer into the gradient interface, the service stability of the material under harsh conditions is significantly improved. The flexible layer can absorb and dissipate the interfacial thermal stress accumulated during extreme temperature cycling through its own micro-plastic deformation, effectively preventing the initiation and propagation of microcracks, greatly enhancing the material's resistance to thermal fatigue, and ensuring that it can maintain a stable structure and excellent thermal conductivity under high and low temperature cycling shock, thereby meeting the stringent requirements of high-end application fields for the long-term reliability of materials.

[0026] An adaptive process adjustment mechanism based on raw material characteristics was established, which fundamentally solved the performance fluctuation problem caused by batch-to-batch differences in raw materials. By accurately detecting the physical properties of key raw materials before production and dynamically adjusting subsequent process parameters accordingly, the stability and consistency of the interface structure between different batches of products were ensured. This intelligent production method enables the core performance indicators of composite materials to be stably controlled within a very small range, demonstrating excellent production repeatability and high quality stability, laying a solid foundation for the large-scale, low-cost manufacturing and commercial application of this high-performance material. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a method for preparing a high thermal conductivity copper-based composite material for heat dissipation. First, tungsten atom-anchored diamond particles are prepared: diamond single-crystal particles are placed in a fluidized bed chemical vapor deposition reactor for chemical vapor deposition, coating the diamond surface with a tungsten layer. The process parameters for this step are: reaction temperature 550℃, tungsten hexafluoride gas flow rate 20 sccm, hydrogen flow rate 100 sccm, negative pressure 50 Pa, and deposition time 120 minutes. Next, graphene-tungsten graded-coated diamond-reinforced powder is prepared: the above particles are added to a graphene oxide dispersion, mechanically stirred, freeze-dried, and then coated with a hydrogen / argon mixture. The mixture is subjected to gradient heating heat treatment under a suitable atmosphere. The heat treatment process parameters for this step are: heating to 800℃ at a rate of 10℃ / min and holding at this temperature for 240 minutes. Finally, the obtained reinforced powder is mechanically mixed with spherical copper powder at a volume ratio of 60:40. The mixed powder is solidified and shaped by spark plasma sintering. During the sintering process, a gradient interface structure of diamond-tungsten carbide-tungsten-copper is generated in situ. The sintering process parameters for this step are: vacuum degree better than 5.0 Pa, axial pressure 50 MPa, heating to a peak temperature of 980℃ at a heating rate of 100℃ / min, and holding at pressure for 5 minutes.

[0030] The high thermal conductivity copper-based composite material for heat dissipation prepared by the method in this embodiment has a room temperature thermal conductivity of 865 W / (m·K) and a coefficient of thermal expansion of 6.5 × 10⁻⁶. -6 / K; The coefficient of thermal expansion of this material is well matched with that of semiconductor chip materials such as gallium nitride and silicon carbide. When applied to IGBT modules in new energy vehicles, it can significantly reduce the thermal stress generated during power cycling, reduce the risk of chip cracking, and help improve the long-term reliability of the module.

[0031] Example 2

[0032] The method provided in this embodiment is basically the same as that in Embodiment 1, except for the selection of process parameters. In the preparation of tungsten atom-anchored diamond particles, the reaction temperature is 500℃, the tungsten hexafluoride gas flow rate is 15 sccm, the hydrogen flow rate is 80 sccm, the negative pressure is 60 Pa, and the deposition time is 100 minutes. In the preparation of graphene-tungsten graded coated diamond reinforcing powder, the heat treatment process is to heat to 750℃ at a rate of 8℃ / min and hold at that temperature for 280 minutes. When finally mixed, the volume ratio of reinforcing powder to spherical copper powder is 55:45. The process parameters for spark plasma sintering are: axial pressure of 45 MPa, heating to 950℃ at a heating rate of 80℃ / min, and holding at pressure for 7 minutes.

[0033] The composite material prepared by the method in this embodiment has a room temperature thermal conductivity of 810 W / (m·K) and a coefficient of thermal expansion of 7.2 × 10⁻⁶. -6 / K; The lower diamond content results in a slightly higher coefficient of thermal expansion, but it is still within an acceptable range; This material is suitable for high-end consumer processor heat dissipation substrates where cost is more sensitive and the requirements for matching the coefficient of thermal expansion are slightly less stringent. It can provide an efficient heat dissipation solution with lower material costs, ensuring the stable operation of the processor under high load.

[0034] Example 3

[0035] The method provided in this embodiment is basically the same as that in Embodiment 1, except for the selection of process parameters. In the preparation of tungsten atom-anchored diamond particles, the reaction temperature is 600℃, the tungsten hexafluoride gas flow rate is 25 sccm, the hydrogen flow rate is 120 sccm, the negative pressure is 40 Pa, and the deposition time is 140 minutes. In the preparation of graphene-tungsten graded coated diamond reinforcing powder, the heat treatment process is to heat to 850℃ at a rate of 12℃ / min and hold at that temperature for 200 minutes. When finally mixed, the volume ratio of reinforcing powder to spherical copper powder is 65:35. The process parameters for spark plasma sintering are: axial pressure of 55 MPa, heating to 1000℃ at a heating rate of 120℃ / min, and holding at pressure for 3 minutes.

[0036] In this embodiment, the high content of reinforcing agents results in a lower coefficient of thermal expansion in the final composite material, which is 6.1 × 10⁻⁶. -6 / K, and a thermal conductivity of 852W / (m·K); this characteristic makes it very suitable for applications such as airborne phased array radar T / R components that have strict requirements for matching thermal expansion coefficients. It can better match the CTE of gallium nitride chips and reduce the accumulation of interface thermal stress in a wide temperature range of -55℃ to 150℃, thereby helping to extend the service life of core components.

[0037] Example 4

[0038] The method provided in this embodiment is characterized in that, on the outside of the tungsten metal layer in which diamond particles are anchored by tungsten atoms, an additional silver layer with a thickness of 30 nanometers is deposited by magnetron sputtering, and finally a five-layer gradient interface structure of diamond-tungsten carbide-tungsten-silver-copper is formed after sintering; the remaining process steps and parameters are the same as in Example 1.

[0039] The composite material prepared in this embodiment incorporates a 30-nanometer-thick, highly ductile silver layer as a stress-absorbing layer, which effectively dissipates thermal stress at the interface through plastic deformation. The material has an initial thermal conductivity of 860 W / (m·K) and a CTE of 6.6 × 10⁻⁶. -6 / K; After undergoing 10,000 rapid power cycle tests from -55℃ to 150℃, its thermal conductivity decays by less than 5%, demonstrating excellent thermal fatigue resistance. It is suitable for heat dissipation substrates of data center servers with extremely high reliability requirements for long-term service, ensuring their performance stability during long-term uninterrupted operation.

[0040] Example 5

[0041] The method provided in this embodiment is characterized by adding a raw material batch characteristic detection step before the preparation process; using a laser particle size analyzer to measure the average particle size and specific surface area of ​​each batch of diamond raw materials, and adaptively adjusting subsequent process parameters based on the detection results; for example, when it is detected that the specific surface area (SSA) of a certain batch of diamond raw materials has increased by 5% compared with the reference value, then according to the correlation formula t W =C1 / SSA and m GO =C2·SSA·M Diamond The tungsten layer deposition time is shortened by approximately 5%, and the amount of graphene oxide added is increased by 5%. In addition, this embodiment also adopts the technical solution of Example 4 to deposit a silver layer with a thickness of 30 nanometers; the remaining process parameters are the same as in Example 1.

[0042] The method in this embodiment solves the problem of inconsistent performance caused by batch fluctuations in raw materials by introducing an adaptive process parameter adjustment mechanism based on raw material characteristics. The composite material prepared by this method not only has excellent thermal properties (thermal conductivity of approximately 860 W / (m·K) and CTE of approximately 6.6 × 10⁻⁶), but also... -6 In addition to its reliability in thermal cycling, the batch-to-batch variation of its core performance indicators can be controlled within ±2%. This high degree of production consistency is crucial for large-scale, low-cost manufacturing, ensuring that every heat dissipation substrate produced on a large-scale production line meets the stringent performance requirements of high-end applications (such as 5G communication base stations), significantly improving the product's yield and commercial potential.

[0043] Comparative Example 1

[0044] Pure copper samples were prepared using the same spark plasma sintering process as in Example 1, with spherical copper powder of 99.9% purity as the raw material.

[0045] Comparative Example 2

[0046] Diamond single crystal particles with an average particle size of 100 micrometers (60% by volume) were directly mechanically mixed with spherical copper powder (40% by volume) without any interface modification treatment; then, conventional copper-diamond composite material samples were prepared by solidification molding using the same spark plasma sintering process as in Example 1.

[0047] Comparative Example 3

[0048] The preparation method was basically the same as in Example 1, but the peak sintering temperature was set to 900°C in the spark plasma sintering process step. This temperature is lower than the preferred range of the present invention (950°C-1000°C); the other process parameters were the same as in Example 1.

[0049] Performance Testing and Comparison

[0050] To verify the technical effects of the present invention, performance tests were conducted on the samples prepared in Examples 1-5 and Comparative Examples 1-3. The test methods and conditions for each performance index are as follows:

[0051] Thermal conductivity (TC): Tested at room temperature (25°C) using a laser thermal conductivity meter (e.g., NETZSCHLFA467, Germany) according to ASTM E1461 standard; the test sample was processed into a disc with a diameter of 12.7 mm and a thickness of 2 mm; to ensure data accuracy, three different locations were measured for each sample, and the arithmetic mean of the results was taken.

[0052] Coefficient of thermal expansion (CTE): Tested according to ASTM E228 standard using a pusher-type thermal expansion tester (e.g., NETZSCHDIL402C, Germany); the test sample was processed into a rectangular specimen of 4 mm × 4 mm × 10 mm; the test was carried out in the temperature range of 25 °C to 150 °C, and the average linear thermal expansion coefficient value of this range was recorded.

[0053] Thermal cycling reliability: The samples were subjected to rigorous thermal cycling tests using a high and low temperature shock test chamber. The cycling temperature range was set from -55℃ to 150℃, the heating and cooling rate was 15℃ / minute, and the temperature was held constant for 15 minutes at the highest and lowest temperatures for one cycle. After a total of 10,000 cycles were completed, the room temperature thermal conductivity of the samples was tested again using the above method, and the percentage decrease in thermal conductivity relative to the initial value (TC decay rate) was calculated.

[0054] Batch consistency: To evaluate the stability of the process, thermal conductivity tests were conducted on three different batches of samples prepared consecutively according to the example scheme. The performance fluctuation range was quantified by calculating the relative standard deviation of the thermal conductivity test values ​​of multiple batches of samples.

[0055] The performance test results of the above embodiments and comparative samples are summarized in the table below:

[0056]

[0057] As shown in the table above, the composite materials prepared in Examples 1-5 of this invention exhibit significantly improved thermal conductivity and coefficient of thermal expansion compared to pure copper in Comparative Example 1 and conventional composite materials in Comparative Example 2. This is attributed to the effective reduction of interfacial thermal resistance by the designed gradient interface structure. The results of Comparative Example 3 indicate that sintering temperature is a key factor in forming a high-quality interface. Insufficient temperature (900℃) leads to inadequate interfacial reaction, preventing the material properties from achieving the expected results of this invention. Example 4, by introducing a flexible silver layer, significantly improves thermal cycling reliability while maintaining high thermal conductivity and low coefficient of thermal expansion. Based on Example 4, Example 5 further introduces an adaptive process adjustment mechanism, successfully reducing performance fluctuations from over ±8% to within ±2%, demonstrating the stability and reliability of this technology in large-scale production.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high thermal conductivity copper-based composite material for heat dissipation, characterized in that, Includes the following steps: Graphene-tungsten graded coated diamond-reinforced powder and spherical copper powder are mechanically mixed in a planetary ball mill to obtain a uniform composite powder. The uniform composite powder is loaded into a mold and solidified in a vacuum environment using a spark plasma sintering process. During the sintering process, a gradient interface structure of diamond-tungsten carbide-tungsten-copper is generated in situ to obtain a high thermal conductivity copper-based composite material for heat dissipation. The preparation of graphene-tungsten hierarchically coated diamond-reinforced powder includes the following steps: Graphene oxide and deionized water were ultrasonically dispersed to obtain a uniform graphene oxide dispersion. Tungsten atom-anchored diamond particles were added to the graphene oxide dispersion and mechanically stirred to obtain a mixed slurry. The mixed slurry was freeze-dried to coat the surface of the tungsten atom-anchored diamond particles with graphene oxide. The coated powder was subjected to gradient heating heat treatment in a hydrogen / argon mixed atmosphere to obtain graphene-tungsten hierarchically coated diamond-reinforced powder. The preparation of tungsten atom-anchored diamond particles includes the following steps: Diamond single crystal particles are placed in a fluidized bed chemical vapor deposition reactor. Argon gas is introduced as a carrier gas and heated while the bed is fluidized. Tungsten hexafluoride and hydrogen are introduced as reaction gases to carry out chemical vapor deposition reaction, coating the surface of the diamond single crystal particles with a tungsten metal layer, thus obtaining tungsten atom-anchored diamond particles.

2. The method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to claim 1, characterized in that, The volume ratio of graphene-tungsten graded coated diamond-reinforced powder to spherical copper powder is (55-65):(45-35).

3. The method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to claim 1, characterized in that, The process parameters for chemical vapor deposition are as follows: reaction temperature 500-600℃, tungsten hexafluoride gas flow rate 15-25 sccm, hydrogen flow rate 80-120 sccm, negative pressure 40-60 Pa, and deposition time 100-140 minutes.

4. The method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to claim 1, characterized in that, The process parameters for gradient heating heat treatment are: heating to 750-850℃ at a rate of 8-12℃ / min, and holding at this temperature for 200-280 minutes.

5. The method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to claim 1, characterized in that, The process parameters for spark plasma sintering are: vacuum degree better than 5.0 Pa, axial pressure of 45-55 MPa; heating to a peak temperature of 950-1000 °C at a heating rate of 80-120 °C / min; and holding pressure for sintering at the peak temperature for 3-7 minutes.

6. The method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to claim 1, characterized in that, Between the tungsten metal layer anchoring diamond particles with tungsten atoms and spherical copper powder, a silver layer with a thickness of 25-35 nanometers is deposited by magnetron sputtering to form a gradient interface structure of diamond-tungsten carbide-tungsten-silver-copper.

7. The method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to claim 1, characterized in that, The process includes a batch characteristic detection step for raw materials, which uses a laser particle size analyzer to measure the average particle size and specific surface area of ​​each batch of diamond raw materials, and adaptively adjusts subsequent process parameters based on the detection results. These process parameters include tungsten layer deposition time and graphene oxide addition amount.

8. A high thermal conductivity copper-based composite material for heat dissipation, prepared by the method for preparing a high thermal conductivity copper-based composite material for heat dissipation according to any one of claims 1-7, characterized in that, include: Copper substrate; And graphene-tungsten hierarchically coated diamond reinforcement distributed in a copper matrix; A gradient interface structure of diamond-tungsten carbide-tungsten-copper is formed between the diamond reinforcement and the copper matrix.

9. The high thermal conductivity copper-based composite material for heat dissipation according to claim 8, characterized in that, The gradient interface structure consists of a five-layer gradient interface of diamond-tungsten carbide-tungsten-silver-copper.

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