An h-bn@wc core-shell structure composite material and a preparation method and application thereof

Abstract

This invention belongs to the field of WC composite material preparation technology, specifically an h-BN@WC core-shell structure composite material, its preparation method, and its application. The composite material uses h-BN as the core layer, with a WC shell layer covering the h-BN, the thickness of which is 400-800 nm. Using sucrose as the carbon source, the h-BN@C ​​material is prepared by hydrothermal synthesis. The h-BN@C ​​material is then ball-milled and mixed with WO3, followed by high-temperature sintering to form the h-BN@WC core-shell structure composite material. This invention avoids the localized inhomogeneities caused by conventional physical mixing, improving the uniformity of the composite material. It eliminates the need for complex physical coating equipment. The resulting core-shell structure composite material combines the high hardness of WC with the excellent thermal conductivity, mechanical properties, and wear resistance of h-BN, enhancing the high-temperature oxidation resistance and wear resistance of WC-Co based cemented carbides, thereby improving their service performance and lifespan.

Description

Technical Field

[0001] This invention belongs to the field of WC composite material preparation technology, specifically an h-BN@WC core-shell structure composite material, its preparation method, and its application. Background Technology

[0002] WC-Co based cemented carbide is a commonly used cemented carbide for tunnel boring machine (TBM) cutters. It consists of a tungsten carbide hard phase and a cobalt metal binder phase. While WC (tungsten carbide) possesses high hardness, effectively enabling rock breaking and tunneling, its wear resistance and high-temperature oxidation resistance are insufficient. In practical applications, when WC-Co alloy cutter heads generate localized high temperatures due to prolonged friction, the cobalt metal softens, causing WC particles to oxidize (oxidation initiation temperature approximately 500-600°C). This leads to a decrease in the hardness of the WC-Co alloy, accelerated wear, and a shortened service life, severely impacting the tunneling efficiency of the TBM and increasing replacement costs. Therefore, an improvement method is urgently needed to enhance the wear resistance and high-temperature oxidation resistance of WC.

[0003] h-BN, known as "white graphene," possesses excellent thermal conductivity, mechanical properties, and wear resistance. Studies have shown that adding h-BN to wood-based ceramic (WC) materials helps reduce the coefficient of friction and improves wear resistance. Furthermore, h-BN maintains good oxidation resistance and wear resistance above 800℃, effectively enhancing the high-temperature oxidation resistance of WC. In addition, the addition of h-BN can also act as a stress buffer, effectively improving the impact resistance of WC.

[0004] Patent CN104072138B discloses a tungsten carbide-cubic boron nitride composite material and its preparation method. Cobalt nanoparticles are coated onto the surface of WC using chemical vapor deposition, and a SiO2 layer is coated onto the surface of cBN. The coated WC and cBN are then mixed and sintered to prepare a bulk tungsten carbide-cubic boron nitride composite material. By coating and uniformly dispersing the powder, the amount of cobalt used is reduced, improving the hardness and thermal stability of the composite material. However, in this patent, WC and cBN are simply physically blended. Physically blended composite materials are multi-component mixtures, and their morphology is difficult to control. Agglomeration is prone to occur during the preparation process, leading to significant fluctuations in the material's performance and failing to effectively improve the wear resistance and high-temperature oxidation resistance of the composite material. Patent CN116833412A discloses a method for preparing a tungsten carbide-cubic boron nitride composite material. The method involves uniformly mixing tungsten carbide, cubic boron nitride, cobalt, chromium carbide, titanium carbide, and aluminum according to a weight ratio using a mixer, then purifying the mixture in a vacuum furnace, followed by isostatic pressing to form a tool bar shape, and finally low-pressure sintering. This patent also involves the physical mixing of tungsten carbide, cubic boron nitride, and other raw materials to prepare the tungsten carbide-boron nitride composite material, which has limited effect on improving wear resistance and high-temperature oxidation resistance.

[0005] Core-shell structured materials are created by coating one material onto another through chemical or strong interactions. In a core-shell structure, the core and shell form strong interfacial interactions through chemical bonds, resulting in strong interfacial bonding and a well-defined structure, which effectively improves the overall performance of the composite material. Furthermore, the performance can be precisely controlled by adjusting parameters such as shell thickness and composition. Currently, there are few reports on h-BN@WC core-shell structured composite materials in existing technologies. Summary of the Invention

[0006] To address the above problems, this invention provides an h-BN@WC core-shell composite material, its preparation method, and its applications. The h-BN@WC core-shell composite material is obtained using a carbothermal reduction reaction and atmospheric sintering process, eliminating the need for complex physical coating equipment and ensuring easy control of the operation process. The h-BN@WC core-shell composite material combines the high hardness of tungsten carbide with the excellent thermal conductivity, mechanical properties, and wear resistance of h-BN. It can directly replace WC in the preparation of WC-Co based cemented carbide. The good thermal conductivity of h-BN enables timely and effective heat dissipation, thereby improving the high-temperature oxidation resistance and wear resistance of WC-Co based cemented carbide, enhancing its service performance and lifespan, and expanding its application in tunnel boring machines.

[0007] The present invention is specifically achieved through the following technical solution: According to the present invention, an h-BN@WC core-shell structure composite material is proposed, which has h-BN as the core layer and h-BN covered with a WC shell layer. The thickness of the h-BN core layer is 400-700 nm and the thickness of the WC shell layer is 400-800 nm.

[0008] This invention also provides a method for preparing the above-mentioned h-BN@WC core-shell structured composite material, specifically including the following steps:

[0009] (1) Add h-BN powder and sucrose to deionized water and stir evenly. Adjust the pH of the resulting mixture to 1~6. Then put the mixture into a reaction stirring vessel for hydrothermal reaction. After the reaction is completed, wash the product with anhydrous ethanol and deionized water 2~4 times each. Dry the obtained solid product to obtain h-BN@C ​​material. h-BN@C ​​material has a core-shell structure, with h-BN as the core layer and h-BN coated with a C layer.

[0010] (2) WO3 and the h-BN@C ​​material prepared in step (1) and a certain amount of anhydrous ethanol are placed in a ball mill and mixed to obtain composite powder;

[0011] (3) The obtained composite powder is placed in a tube furnace under an argon atmosphere for sintering treatment. The sintering temperature is 1400~1700℃ and the sintering time is 2~8 h to obtain h-BN@WC core-shell structure composite material.

[0012] In the aforementioned preparation method of h-BN@WC core-shell composite material, the preferred mass ratio of h-BN powder, sucrose, and deionized water in step (1) is 3:20:75, the preferred particle size of h-BN powder is 1~10 μm, the purity of sucrose is analytical grade, and the solution used to adjust the pH of the mixed system is a 36% hydrochloric acid solution.

[0013] In the aforementioned method for preparing h-BN@WC core-shell composite material, the hydrothermal reaction temperature in step (1) is preferably 180℃~200℃, the reaction pressure is preferably 1~5 MPa, the reaction time is preferably 1~5 h, the stirring speed of the reaction vessel is preferably 400~500 r / min, and the solid product is dried in a vacuum drying oven at 80℃ for 10~20 h to obtain h-BN@C ​​material.

[0014] The preparation method of the aforementioned h-BN@WC core-shell composite material, the C layer coating thickness of the h-BN@C ​​material obtained in step (1) is about 400-700 nm.

[0015] In the aforementioned preparation method of h-BN@WC core-shell composite material, the mass ratio of WO3, h-BN@C ​​material and anhydrous ethanol in step (2) is 0.5~0.9:1:1.5~2.5, and the particle size of WO3 is 500~1000 nm.

[0016] In the aforementioned preparation method of h-BN@WC core-shell composite material, in step (2), zirconium oxide balls are used for grinding, the mass ratio of material to grinding balls is preferably 1:2.5, the ball mill speed is preferably 300~600 r / min, and the mixing time is preferably 6~8h.

[0017] In the aforementioned method for preparing h-BN@WC core-shell composite material, h-BN is the core layer and WC is the shell layer covering h-BN, with a shell thickness of approximately 400~800 nm.

[0018] This invention also provides an application of the h-BN@WC core-shell composite material obtained according to the aforementioned preparation method in the preparation of h-BN@WC-Co alloys. The h-BN@WC core-shell composite material replaces the WC (tungsten carbide) in the YG7 alloy by an equal mass, while other conditions remain unchanged. The h-BN@WC-Co alloy is then prepared according to existing alloy preparation processes. The impact resistance of this h-BN@WC-Co alloy is 1.3-1.5 J / cm². 2 Its thermal conductivity is 125-150 W / (m·K).

[0019] Compared with the prior art, the present invention has significant advantages and beneficial effects, achieving considerable technological progress and practicality, and has broad application value. It possesses at least the following advantages:

[0020] (1) This invention uses sucrose as a carbon source. By adjusting the pH of the mixing system, a hydrothermal method is used to attach the carbon source to the surface of h-BN to form a uniform and dense C layer, thus forming an h-BN@C ​​core-shell structure material. This avoids the problems of carbon layer agglomeration or insufficient local coating, and provides a C source for the subsequent in-situ growth of the WC shell layer. Subsequently, the h-BN@C ​​core-shell structure material is ball-milled and mixed with WO3 and then sintered at high temperature. The WC shell layer is grown in situ on the surface of h-BN by means of a carbothermal reduction reaction, forming an h-BN@WC core-shell structure composite material. In this composite material, h-BN is located in the core layer, and WC coats the surface of h-BN to form a shell layer. h-BN@WC core-shell composite materials combine the high hardness of tungsten carbide with the excellent thermal conductivity, mechanical properties, and wear resistance of h-BN. They can directly replace WC in WC-Co based cemented carbide to prepare h-BN@WC-Co alloys. The good thermal conductivity of h-BN can dissipate heat in a timely and effective manner, thereby improving the high-temperature oxidation resistance and wear resistance of h-BN@WC-Co alloys, and enhancing their service performance and service life.

[0021] (2) h-BN materials do not wet most metals and are difficult to form an effective bonding interface with metals. Therefore, compared with the simple physical mixing method, the h-BN@WC core-shell structure composite material prepared by the present invention has h-BN in the inner core layer and is covered with tungsten carbide on the outside. When preparing h-BN@WC-Co alloy, h-BN does not directly contact metal Co, thus solving the problem of interface wettability between h-BN and metal and effectively reducing the micro-defects of the material.

[0022] (3) The h-BN@WC core-shell composite material prepared by this invention avoids the local inhomogeneity problem caused by conventional physical mixing and improves the uniformity of the composite material. At the same time, when the h-BN@WC core-shell composite material is applied in the ceramic field, the WC shell can also serve as an intermediate transition phase to coordinate the thermal compatibility differences between h-BN and subsequent added materials, thereby enhancing the comprehensive performance of h-BN-based composite ceramics.

[0023] (4) The present invention uses carbothermal reduction reaction and atmosphere sintering process to obtain h-BN@WC core-shell structure composite material. It does not require complicated physical coating equipment, the operation process is simple and easy to control, and it can realize the batch preparation of core-shell structure composite material with high production efficiency. Attached Figure Description

[0024] Figure 1 In the middle (a) and (b), respectively, are SEM images of the h-BN and h-BN@WC core-shell composite materials in Example 1.

[0025] Figure 2 This is the XRD pattern of the h-BN@WC core-shell composite material prepared in Example 1.

[0026] Figure 3 In the middle (a) and (b), respectively, are TEM images of the h-BN@C ​​material and the h-BN@WC core-shell composite material prepared in Example 2. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. 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.

[0028] Unless otherwise specified, all conditions in the following examples were performed under standard conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products.

[0029] Example 1

[0030] (1) 6 g of h-BN powder with a particle size of about 7 µm was mixed with 40 g of sucrose of analytical grade and 150 g of deionized water to obtain a mixed system. HCl solution was added to adjust the pH of the mixed system to 4. The mixed system was then placed in a reaction stirred tank for hydrothermal reaction. The stirring speed of the reaction stirred tank was 500 r / min, the temperature was 180℃, the pressure was 1 MPa, and the reaction time was 3 h. After the reaction was completed, the product was washed twice by vacuum filtration with anhydrous ethanol and deionized water respectively. The obtained solid product was vacuum dried at 80℃ for 12 h to obtain h-BN@C ​​material. h-BN@C ​​material has a core-shell structure, with h-BN as the core layer and C layer (carbon layer) covering the outside of h-BN. The coating thickness of C layer is about 600 nm.

[0031] (2) 5 g of WO3 with a particle size of 600 nm, 10 g of h-BN@C ​​material prepared in step (1) and 18 g of anhydrous ethanol were put into a drum ball mill for mixing. The grinding balls were zirconia balls, the mass ratio of material to grinding balls was 1:2.5, the ball mill speed was 500 r / min, and the mixing time was 7 h to obtain composite powder.

[0032] (3) The obtained composite powder was placed in a tube furnace under an argon atmosphere for sintering treatment. The sintering temperature was 1400℃ and the sintering time was 8 h to obtain h-BN@WC core-shell composite material.

[0033] Figure 1 Images (a) and (b) in this embodiment are SEM images of the h-BN and the prepared h-BN@WC core-shell composite material, respectively. Figure 1 As can be seen in (a), the h-BN particles have smooth surfaces, with some small, plate-like h-BN particles distributed on the surface of the larger particles, and no other impurity particles. Figure 1 As can be seen in (b), the surface of h-BN@WC particles is generally rough, and the smooth surface of h-BN cannot be observed, which proves that WC forms an effective coating layer on the surface of h-BN, and the coating thickness of the WC layer is about 500 nm.

[0034] Figure 2 The image shows the XRD pattern of the h-BN@WC core-shell composite material prepared in this embodiment. It can be seen that only h-BN and WC phases exist in the prepared h-BN@WC core-shell composite material, and no other phases exist, indicating that C and WO3 react completely and the sample has high purity.

[0035] The h-BN@WC core-shell composite material prepared in Example 1 was used to replace WC in the YG7 alloy with an equal mass, while keeping other conditions unchanged. The h-BN@WC-Co alloy was prepared according to the existing YG7 alloy preparation process. The dry wear performance, impact resistance and thermal conductivity of the YG7 alloy and the h-BN@WC-Co alloy were tested.

[0036] The dry wear performance test method includes: pressing the sample onto a rotating steel mating wheel; the sample size is 70 mm × 25 mm × 10 mm; applying a load of 130 N; introducing abrasive material (quartz sand with a particle size of 150–300 μm) between the steel mating wheel and the sample; rotating the steel mating wheel at a speed of 1 m / s; and achieving an abrasive flow rate of 150 g / min on the contact surface between the sample and the steel mating wheel. The dry wear performance test is conducted at room temperature and in air for 20 minutes. The dry wear performance is expressed as the sample mass loss M (unit: g), where M = initial sample mass - mass of sample after wear test. Each sample group is tested at least three times to reduce error.

[0037] The impact resistance test method includes: according to GB / T 229-2020 standard, an impact test is conducted using a pendulum. The radius of curvature of the pendulum hammer edge is 2 mm. To avoid the influence of machining notches, unnotched specimens are used in the test. The specimen size is 55 mm × 10 mm × 10 mm. The test is conducted at room temperature. Each group of samples is tested at least 3 times to reduce errors.

[0038] Thermal conductivity test: The thermal conductivity of the sample was tested using a laser thermal conductivity meter. The sample was a solid circular disc with a diameter of 12.7 mm and a thickness of 4 mm.

[0039] Tests showed that the dry wear resistance of YG7 alloy was 0.030 g, and its impact resistance was approximately 1 J / cm. 2 The thermal conductivity is 95 W / (m·K). The dry wear resistance of the h-BN@WC-Co alloy is 0.020 g, and the impact resistance is approximately 1.5 J / cm. 2 With a thermal conductivity of 150 W / (m·K), it is evident that the performance of the h-BN@WC-Co alloy is significantly higher than that of the conventional YG7 alloy.

[0040] Example 2

[0041] (1) 6 g of h-BN powder with a particle size of about 5 µm was mixed with 40 g of sucrose of analytical grade and 150 g of deionized water to obtain a mixed system. HCl solution was added to adjust the pH of the mixed system to 6. The mixed system was then placed in a reaction stirred tank for hydrothermal reaction. The stirring speed of the reaction stirred tank was 400 r / min, the temperature was 180℃, the pressure was 2 MPa, and the reaction time was 2 h. After the reaction was completed, the product was washed twice by vacuum filtration with anhydrous ethanol and deionized water respectively. The obtained solid product was vacuum dried at 80℃ for 10 h to obtain h-BN@C ​​material. h-BN@C ​​material has a core-shell structure, with h-BN as the core layer and C layer (carbon layer) covering the outside of h-BN. The coating thickness of C layer is about 600 nm.

[0042] (2) 6 g of WO3 with a particle size of 600 nm, 10 g of h-BN@C ​​material prepared in step (1) and 22 g of anhydrous ethanol were put into a drum ball mill for mixing. The grinding balls were zirconia balls, the mass ratio of material to grinding balls was 1:2.5, the ball mill speed was 600 r / min, and the mixing time was 6 h to obtain composite powder.

[0043] (3) The obtained composite powder was placed in a tube furnace under an argon atmosphere for sintering treatment. The sintering temperature was 1500℃ and the sintering time was 6 h to obtain h-BN@WC core-shell composite material.

[0044] Figure 3 In Figures (a) and (b), TEM images of the h-BN@C ​​material and h-BN@WC core-shell composite material prepared in Example 2 are shown, respectively. Figure 3 As shown in (a), the h-BN@C ​​material formed after carbon coating still has a sheet-like structure. As h-BN@C ​​reacts with WO3 to form h-BN@WC, the sheet-like structure transforms into a near-spherical shape, and the particle diameter increases, proving that WC effectively coats the h-BN surface to form a core-shell structure. The coating thickness of the WC layer is approximately 800 nm.

[0045] The h-BN@WC core-shell composite material prepared in Example 2 was used to replace WC in the YG7 alloy by an equal mass, while keeping other conditions unchanged. The h-BN@WC-Co alloy was then prepared using the existing YG7 alloy preparation process. The dry wear performance, impact resistance, and thermal conductivity of the h-BN@WC-Co alloy were tested using the same methods as in Example 1. The tests showed that the dry wear performance of the h-BN@WC-Co alloy in this example was 0.022 g, and the impact resistance was approximately 1.4 J / cm. 2 Its thermal conductivity is 135 W / (m·K), which is higher than that of conventional YG7 alloys.

[0046] Example 3

[0047] (1) 6 g of h-BN powder with a particle size of about 3 µm was mixed with 40 g of sucrose of analytical grade and 150 g of deionized water to obtain a mixed system. HCl solution was added to adjust the pH of the mixed system to 3. The mixed system was then placed in a reaction stirred tank for hydrothermal reaction. The stirring speed of the reaction stirred tank was 500 r / min, the temperature was 200℃, the pressure was 3 MPa, and the reaction time was 1 h. After the reaction was completed, the product was washed twice by vacuum filtration with anhydrous ethanol and deionized water respectively. The obtained solid product was vacuum dried at 80℃ for 16 h to obtain h-BN@C ​​material. h-BN@C ​​material has a core-shell structure, with h-BN as the core layer and C layer (carbon layer) covering the outside of h-BN. The coating thickness of C layer is about 500 nm.

[0048] (2) 8 g of WO3 with a particle size of 700 nm, 10 g of h-BN@C ​​material prepared in step (1) and 22 g of anhydrous ethanol were put into a drum ball mill for mixing. The grinding balls were zirconia balls, the mass ratio of material to grinding balls was 1:2.5, the ball mill speed was 400 r / min, and the mixing time was 7 h to obtain composite powder.

[0049] (3) The obtained composite powder was placed in a tube furnace under an argon atmosphere for sintering at a temperature of 1600℃ for 4 h to obtain h-BN@WC core-shell composite material. The coating thickness of the WC layer in the h-BN@WC core-shell composite material was measured to be approximately 800 nm.

[0050] The h-BN@WC core-shell composite material prepared in Example 3 was used to replace WC in the YG7 alloy by an equal mass, while keeping other conditions unchanged. The h-BN@WC-Co alloy was then prepared using the existing YG7 alloy preparation process. The dry wear performance, impact resistance, and thermal conductivity of the h-BN@WC-Co alloy were tested using the same methods as in Example 1. The tests showed that the dry wear performance of the h-BN@WC-Co alloy in this example was 0.025 g, and the impact resistance was approximately 1.3 J / cm.2 Its thermal conductivity is 128 W / (m·K).

[0051] Example 4

[0052] (1) 6 g of h-BN powder with a particle size of about 3 µm was mixed with 40 g of sucrose of analytical grade and 150 g of deionized water to obtain a mixed system. HCl solution was added to adjust the pH of the mixed system to 1. The mixed system was then placed in a reaction stirred tank for hydrothermal reaction. The stirring speed of the reaction stirred tank was 400 r / min, the temperature was 200℃, the pressure was 3 MPa, and the reaction time was 1.5 h. After the reaction was completed, the product was washed twice by vacuum filtration with anhydrous ethanol and deionized water respectively. The obtained solid product was vacuum dried at 80℃ for 18 h to obtain h-BN@C ​​material. h-BN@C ​​material has a core-shell structure, with h-BN as the core layer and C layer (carbon layer) covering the outside of h-BN. The coating thickness of C layer is about 700 nm.

[0053] (2) 9 g of WO3 with a particle size of 700 nm, 10 g of h-BN@C ​​material prepared in step (1) and 22 g of anhydrous ethanol were put into a drum ball mill for mixing. The grinding balls were zirconia balls, the mass ratio of material to grinding balls was 1:2.5, the ball mill speed was 500 r / min, and the mixing time was 8 h to obtain composite powder.

[0054] (3) The obtained composite powder was placed in a tube furnace under an argon atmosphere for sintering at a temperature of 1700℃ for 3 h to obtain h-BN@WC core-shell composite material. The coating thickness of the WC layer in the h-BN@WC core-shell composite material was measured to be approximately 600 nm.

[0055] The h-BN@WC core-shell composite material prepared in Example 4 was used to replace WC in the YG7 alloy by an equal mass, while keeping other conditions unchanged. The h-BN@WC-Co alloy was then prepared using the existing YG7 alloy preparation process. The dry wear performance, impact resistance, and thermal conductivity of the h-BN@WC-Co alloy were tested using the same methods as in Example 1. The test results showed that the dry wear performance of the h-BN@WC-Co alloy in this example was 0.021 g, and the impact resistance was approximately 1.4 J / cm. 2 Its thermal conductivity is 146 W / (m·K).

[0056] This invention utilizes a carbothermal reduction reaction and atmospheric sintering process to obtain h-BN@WC core-shell composite materials. It eliminates the need for complex physical coating equipment, features a simple and controllable operation process, and enables mass production of core-shell composite materials with high efficiency. The h-BN@WC core-shell composite material combines the high hardness of tungsten carbide with the excellent thermal conductivity, mechanical properties, and wear resistance of h-BN. It can directly replace WC in WC-Co based cemented carbides for the preparation of h-BN@WC-Co alloys, improving the alloy's high-temperature oxidation resistance and wear resistance, thereby enhancing its service performance and lifespan.

[0057] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art 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 scope of the present invention.

Claims

1. An h-BN@WC-Co alloy, characterized in that, By replacing the WC in the YG7 alloy with an h-BN@WC core-shell composite material, an h-BN@WC-Co alloy was prepared using the same process as the YG7 alloy. The impact resistance of the h-BN@WC-Co alloy was 1.3-1.5 J / cm². 2 The thermal conductivity is 125-150 W / (m·K); the h-BN@WC core-shell composite material has h-BN as the core layer and a WC shell layer covering h-BN. The thickness of the h-BN core layer is 400-700 nm, and the thickness of the WC shell layer is 400-800 nm; the h-BN@WC core-shell composite material is prepared according to the following method: (1) Add h-BN powder and sucrose to deionized water and stir evenly. Adjust the pH of the resulting mixture to 1-6. Then place the mixture in a reaction vessel and hydrothermally react at 180℃-200℃ for 1-5 h. The stirring speed of the reaction vessel is 400-500 r / min and the reaction pressure is 1-5 MPa. After the reaction is completed, wash the product with anhydrous ethanol and deionized water 2-4 times each. Dry the obtained solid product to obtain h-BN@C ​​material. h-BN@C ​​material has a core-shell structure, with h-BN as the core layer and a C layer covering h-BN with a coating thickness of 400-700 nm. The mass ratio of h-BN powder, sucrose and deionized water is 3:20:

75. (2) Mix WO3 with the h-BN@C ​​material prepared in step (1) and a certain amount of anhydrous ethanol in a ball mill to obtain composite powder. The mass ratio of WO3, h-BN@C ​​material and anhydrous ethanol is 0.5~0.9:1:1.5~2.

5. (3) The obtained composite powder is placed in a tube furnace under an argon atmosphere for sintering treatment. The sintering temperature is 1400~1700℃ and the sintering time is 2~8 h to obtain h-BN@WC core-shell structure composite material.

2. The h-BN@WC-Co alloy as described in claim 1, characterized in that, In step (1), the h-BN powder has a particle size of 1~10μm and the sucrose purity is analytical grade.

3. The h-BN@WC-Co alloy as described in claim 1, characterized in that, In step (1), the solid product is dried in a vacuum drying oven at 80°C for 10-20 h.

4. The h-BN@WC-Co alloy as described in claim 1, characterized in that, In step (2), the particle size of WO3 is 500~1000nm.

5. The h-BN@WC-Co alloy as described in claim 1, characterized in that, In step (2), zirconia balls are used for grinding, the mass ratio of material to grinding balls is 1:2.5, the ball mill speed is 300~600 r / min, and the mixing time is 6~8 h.

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