High-wear-resistance tungsten carbide alloy and preparation method thereof

Abstract

The invention discloses a high-wear-resistance tungsten carbide alloy and a preparation method thereof, and belongs to the technical field of tungsten carbide alloys. According to the high-wear-resistance tungsten carbide alloy, spherical hard particles are evenly distributed in a matrix, the mass percent of the hard particles is 80 wt.%-90 wt.%, and the mass percent of the matrix is 10 wt.%-20 wt.%; the hard particles comprise the following components in percentage by mass: 75 to 80 weight percent of composite tungsten carbide particles, 5 to 10 weight percent of cobalt powder, 2 to 3 weight percent of titanium powder, 2 to 3 weight percent of zirconium powder, 0.5 to 1 weight percent of rare earth oxide and 5 to 10 weight percent of nano carbon black. By adopting the wear-resistant tungsten carbide alloy and the preparation method thereof, the problem that the wear resistance of the tungsten carbide alloy is affected due to the fact that the hardness and the toughness of the existing tungsten carbide alloy cannot be synergistically enhanced can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tungsten carbide alloys, in particular to a high-wear-resistant tungsten carbide alloy and a preparation method thereof. Background Art

[0002] As a typical cemented carbide material, tungsten carbide alloy is widely used in cutting tools, mining machinery, oil extraction, aerospace and other fields due to its high hardness, high wear resistance and good high-temperature stability. In actual working conditions, tungsten carbide alloy needs to have excellent strength, toughness and wear resistance at the same time to withstand complex mechanical stress, impact loads and friction losses. Existing tungsten carbide alloys generally use tungsten carbide as the hard phase and cobalt as the bonding phase. Pure tungsten carbide as the hard phase is effective in improving the hardness of tungsten carbide alloy. In addition, cobalt as a bonding phase is prone to softening under high temperature conditions, affecting the strength, hardness and wear resistance of the matrix.

[0003] Increasing the content of tungsten carbide particles and refining their grain size can significantly enhance the hardness and strength of the alloy, thereby improving its wear resistance. However, this will lead to a decrease in the thickness of the bonding phase between the tungsten carbide particles, reducing the alloy's ability to resist crack propagation, resulting in a significant decrease in toughness. Once tiny cracks appear in the alloy during service, due to the lack of sufficient toughness buffer, the cracks will rapidly expand, causing material failure and weakening its wear resistance. Conversely, although increasing the content of the bonding phase or improving the plasticity of the bonding phase can effectively improve the toughness of the alloy, the bonding phase itself has a low hardness. Excessive bonding phase will reduce the overall hardness of the alloy, making the material more susceptible to plastic deformation and adhesive wear during friction, resulting in a decrease in wear resistance.

[0004] Existing patent CN202111074553.8 discloses a highly wear-resistant WC-Co-based alloy and its preparation method, including S1, ball-milling and wet-mixing coarse-grained tungsten carbide, ultrafine tungsten powder, ultrafine cobalt powder, tantalum carbide, paraffin wax and stearic acid to obtain a slurry; S2, filtering the slurry obtained in step S1 and drying it, granulating and pressing the dry material to obtain a blank; S3, sintering the blank obtained in step S2, and the sintering includes four stages, namely dewaxing, vacuum sintering, low-pressure sintering and cooling, to finally obtain a WC-Co-based alloy. By compounding the raw material formula of the alloy and combining it with a specific sintering process, the precipitation of nano-granular decarburized phase is achieved in the Co phase of the alloy, thereby significantly enhancing the wear resistance of the alloy without significantly reducing the bending strength, and significantly improving the service life of the tools / parts produced. However, the above patent relies on the precipitation of nano-granular decarburization phase to effectively improve the wear resistance of the alloy, and cobalt, as a binding phase, is easily softened under high temperature conditions during cutting, affecting the wear resistance of the alloy. Summary of the Invention

[0005] The purpose of the present invention is to provide a high wear-resistant tungsten carbide alloy and a preparation method thereof, so as to solve the problem that the hardness and toughness of the existing tungsten carbide alloy cannot be enhanced synergistically, which affects the wear resistance of the tungsten carbide alloy.

[0006] To achieve the above objectives, the present invention provides a highly wear-resistant tungsten carbide alloy, comprising a matrix and hard particles, wherein the spherical hard particles are uniformly distributed in the matrix, the mass percentage of the hard particles is 80wt.%-90wt.%, and the mass percentage of the matrix is ​​10wt.%-20wt.%; the hard particles comprise 75wt.%-80wt.% of composite tungsten carbide particles, 5wt.%-10wt.% of cobalt powder, 2wt.%-3wt.% of titanium powder, 2wt.%-3wt.% of zirconium powder, 0.5wt.%-1wt.% of rare earth oxides, and 5wt.%-10wt.% of nano-carbon black.

[0007] Preferably, the composite tungsten carbide particles include the following components in percentage by mass: 10wt.%-15wt.% of tungsten carbide particles with a particle size of 150nm-200nm, 50wt.%-70wt.% of tungsten carbide particles with a particle size of 0.8μm-1.0μm, and 20wt.%-30wt.% of tungsten carbide particles with a particle size of 2μm-3μm.

[0008] Preferably, the particle size of the cobalt powder is 3 μm-5 μm, the particle size of the titanium powder is 1 μm-2 μm, and the particle size of the zirconium powder is 1 μm-2 μm.

[0009] Preferably, the particle size of the rare earth oxide is 0.5 μm-1.0 μm, and the rare earth oxide is one of cerium oxide and yttrium oxide.

[0010] Preferably, the matrix includes the following components in mass percentage: 70wt.%-80wt.% tungsten carbide, 4wt.%-6wt.% molybdenum carbide, 3wt.%-5wt.% aluminum oxide, 0.1wt.%-0.5wt.% rare earth oxide, 0.5wt.%-1wt.% copper, and 15wt.%-20wt.% cobalt.

[0011] Preferably, the particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0012] The method for preparing the above-mentioned highly wear-resistant tungsten carbide alloy comprises the following steps:

[0013] S1. preparing hard particles;

[0014] S2. Ball-milling tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, zirconium oxide powder, and copper powder in an ethanol medium according to a mass ratio to obtain a matrix raw material;

[0015] S3, adding the hard particles to the matrix raw material and ball milling and mixing, and obtaining raw material powder after uniform mixing; drying the raw material powder and pressing it into raw material blanks;

[0016] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0017] Preferably, said S1 comprises the following steps:

[0018] S11, weighing tungsten carbide particles with a particle size of 150 nm to 200 nm, tungsten carbide particles with a particle size of 0.8 μm to 1.0 μm, and tungsten carbide particles with a particle size of 2 μm to 3 μm according to a mass ratio, and ultrasonically dispersing the tungsten carbide particles in an ethanol medium for 1 hour to 3 hours to obtain composite tungsten carbide particles;

[0019] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 2-3 hours to remove moisture from the nano carbon black;

[0020] S13, mixing composite tungsten carbide particles, nano carbon black, cobalt powder, titanium powder, zirconium powder and rare earth oxide according to a mass ratio, and ball milling the mixture in an ethanol medium to obtain a mixed powder;

[0021] S14, drying the mixed powder, and maintaining the mixed powder under a pressure of 50 MPa-100 MPa for 5 min-10 min to obtain a green body;

[0022] S15, placing the green body into a heating furnace for sintering, using an inert gas for protection during the sintering process, and naturally cooling to room temperature to obtain a sintered product;

[0023] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0024] Preferably, in S15, the sintering temperature is 1400° C.-1500° C., the sintering pressure is 10 MPa-30 MPa, and the holding time is 0.5 h-1 h.

[0025] Preferably, in S4, the sintering temperature is 1300° C.-1400° C., the sintering pressure is 30 MPa-50 MPa, and the sintering time is 20 min-30 min.

[0026] The advantages and positive effects of the high wear-resistant tungsten carbide alloy and the preparation method thereof of the present invention are:

[0027] 1. The composite tungsten carbide particles used in the hard particles of the present invention increase the packing density of tungsten carbide and improve the compactness of the hard particle structure. The synergistic effect of the three-layer particles significantly improves the toughness, strength, and wear resistance of the material.

[0028] 2. The titanium and zirconium powders in the hard particles react with graphite upon heating to form titanium carbide and zirconium carbide hard particles. These particles, harder than tungsten carbide, are evenly distributed in the WC matrix at the submicron level, inhibiting WC grain growth and increasing the hardness and toughness of the hard particles. The TiC / ZrC particles act as "rigid anchors" to secure the cobalt phase, preventing excessive flow and resulting strength loss, thereby improving the high-temperature performance of the hard particles.

[0029] 3. Nano-carbon black is filled between the ceramic particles and the cobalt binder phase to form a "nano-bridge" structure, which enhances the interface bonding force through the mechanical interlocking effect. At the same time, it acts as a stress buffer layer to inhibit the expansion of cracks along the interface, which is beneficial to improving the toughness of hard particles.

[0030] 4. The tungsten carbide and molybdenum carbide particles in the matrix fill the pores between the hard particles to form a "coarse particle skeleton-fine particle filling" structure, which is beneficial to improving the overall hardness and strength of the tungsten carbide alloy.

[0031] 5. The particle size ratio of alumina to tungsten carbide in the matrix is ​​1:10. When the dislocation moves to the position of alumina, it needs to bypass the particles by a bowing mechanism, which greatly increases the energy consumption of dislocation movement and improves the strength and toughness of the matrix.

[0032] 6. Copper and cobalt are used as binders, forming a continuous metal mesh at the interface. This mesh bridges the cracks through plastic deformation, inhibiting crack penetration, improving the bond strength between the hard particles and the matrix, and reducing hard particle shedding. Copper acts as a "rigid node" in the mesh, limiting the plastic flow and softening deformation of cobalt at high temperatures, alleviating the strength loss caused by high-temperature softening of cobalt.

[0033] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION

[0034] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. In the event of any inconsistency, the meaning described in this specification or the meaning derived from the contents recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0035] The embodiments of the present invention are described in detail below.

[0036] A highly wear-resistant tungsten carbide alloy comprises a matrix and hard particles. The spherical hard particles are uniformly distributed in the matrix, with the mass percentage of the hard particles being 80-90% by weight and the mass percentage of the matrix being 10-20% by weight. The hard particles comprise 75-80% by weight of composite tungsten carbide particles, 5-10% by weight of cobalt powder, 2-3% by weight of titanium powder, 2-3% by weight of zirconium powder, 0.5-1% by weight of rare earth oxide, and 5-10% by weight of nano-carbon black.

[0037] The composite tungsten carbide particles include the following components in mass percentage: 10wt.%-15wt.% of tungsten carbide particles with a particle size of 150nm-200nm, 50wt.%-70wt.% of tungsten carbide particles with a particle size of 0.8μm-1.0μm, and 20wt.%-30wt.% of tungsten carbide particles with a particle size of 2μm-3μm.

[0038] The tungsten carbide particles in the hard particles are composed of composite tungsten carbide particles made of nano-, submicron-, and micron-sized tungsten carbide particles. Nano-sized tungsten carbide particles with a particle size of 150nm-200nm are filled into the pores between submicron-sized tungsten carbide particles with a particle size of 0.8μm-1.0μm and micron-sized tungsten carbide particles with a particle size of 2μm-3μm, making the structure of the hard particles denser, reducing the presence of defects, and thus improving the hardness and wear resistance of the hard particles. When the material is subjected to external force and cracks are generated, the micron-sized tungsten carbide particles are mainly responsible for bearing the load and playing a supporting role; the submicron-sized particles can change the crack propagation path and deflect the crack propagation direction; the nano-sized particles can pin the cracks and prevent them from further expansion; the synergistic effect of the three levels of particles is conducive to significantly improving the toughness of the material. During the friction process, particles of different particle sizes can evenly distribute stress on particles of each level, avoiding local rapid wear caused by stress concentration, thereby improving the overall wear resistance of the material.

[0039] The particle size of the cobalt powder is 3 μm-5 μm, the particle size of the titanium powder is 1 μm-2 μm, the particle size of the zirconium powder is 1 μm-2 μm, and the particle size of the rare earth oxide is 0.5 μm-1.0 μm. The rare earth oxide is one of cerium oxide and yttrium oxide.

[0040] The particle sizes of titanium and zirconium powders are similar to those of the composite tungsten carbide particles, which helps improve the uniformity of the mixing of titanium, zirconium, and tungsten carbide particles and enhances the uniformity of the hard particles. When heated, the metallic titanium and cobalt powders react with graphite to form hard titanium carbide and zirconium carbide particles. These particles, harder than tungsten carbide, are uniformly distributed within the WC matrix at the submicron level. When subjected to external forces, dislocation motion is hindered by the hard particles, forcing them to debond and extend along the TiC / ZrC-WC interface, consuming more energy. This contributes to the increased hardness and toughness of the hard particles. The difference in thermal expansion coefficients between TiC and WC generates circumferential residual compressive stress in the WC matrix surrounding the TiC / ZrC particles during cooling. This compressive stress partially offsets the applied tensile stress, increasing dislocation slip resistance and thus enhancing the toughness of the hard particles. TiC / ZrC particles inhibit the growth of WC grains during high-temperature sintering through the grain boundary pinning effect and improve the hardness and toughness of hard particles through the grain refinement strengthening mechanism.

[0041] Nanocarbon black has an extremely small particle size of less than 50nm and a large specific surface area. It provides a highly active carbon source and shortens the diffusion path. The high specific surface area of ​​nanocarbon black increases the number of cobalt, titanium, and zirconium atoms adsorbed on its surface, forming an "atomic-level mixed interface" that accelerates the reaction, promotes the rapid reaction of Ti, Zr atoms with C, and promotes the formation of titanium carbide and zirconium carbide. In addition, nanocarbon black fills the space between the ceramic particles and the cobalt binder phase, forming a "nano-bridge" structure. This mechanical interlocking effect enhances interfacial bonding and acts as a stress buffer layer to inhibit crack propagation along the interface.

[0042] Adding rare earth oxides to hard particles, rare earth oxides decompose into Ce at high temperature 3+ / Y 3+ Cations and O 2 The rare earth anions diffuse into the grain boundaries, where rare earth cations fill grain boundary defects and replace impurity atoms, reducing the precipitation of brittle phases at the grain boundaries and lowering interfacial energy. Rare earth oxides inhibit WC grain growth through a "pinning effect." Grain refinement increases the number of grain boundaries and dislocation slip resistance, which helps improve the hardness and toughness of the hard particles. Furthermore, rare earth oxides reduce the surface tension of the molten cobalt phase, promoting cobalt infiltration into the ceramic particles and enhancing interfacial bonding strength.

[0043] Cobalt powder acts as a binder and melts during the sintering process to form a metal bonding phase. Under pressure, it fully penetrates between tungsten carbide, titanium carbide and zirconium carbide to form a metal bonding network. The tungsten carbide hard particles are firmly combined through metal bonds to form a "ceramic skeleton-metal ligament" composite structure. Under the action of external force, cobalt absorbs impact energy through plastic deformation, while TiC / ZrC particles act as "rigid anchor points" to fix the cobalt phase, preventing its strength loss caused by excessive flow, thereby improving the strength of the hard particles while ensuring their toughness.

[0044] The matrix includes the following components in mass percentage: 70wt.%-80wt.% of tungsten carbide, 4wt.%-6wt.% of molybdenum carbide, 3wt.%-5wt.% of aluminum oxide, 0.1wt.%-0.5wt.% of rare earth oxide, 0.5wt.%-1wt.% of copper, and 15wt.%-20wt.% of cobalt.

[0045] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0046] Molybdenum carbide has very high hardness. As a hard second phase, molybdenum carbide is evenly distributed in the tungsten carbide and binder phase of the matrix. It hinders dislocation movement through a dispersion strengthening mechanism, thereby improving the toughness and hardness of the matrix. Molybdenum carbide and tungsten carbide form a dual hard phase system in the matrix, which alternately withstands cutting, reducing wear damage of a single phase and helping to improve the wear resistance of the tungsten carbide alloy. Molybdenum carbide has a certain solid solubility in tungsten carbide, forming a substitutional solid solution. This substitutional solid solution causes tungsten carbide lattice distortion, increasing dislocation slip resistance, and thus effectively improving the toughness and strength of the matrix.

[0047] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.3μm-0.5μm, and the particle size of hard particles is 20μm-30μm. The tungsten carbide and molybdenum carbide particles in the matrix fill the pores between the hard particles, forming a "coarse particle skeleton-fine particle filling" structure, which reduces defects and increases the packing density, thereby improving the overall hardness and strength of the tungsten carbide alloy. The hard particles act as the "primary load-bearing phase" to bear the main load, while the fine particles in the matrix act as the "secondary reinforcement phase" to share the load through interfacial stress transfer, avoiding the hardness reduction caused by local stress concentration, which is beneficial to improving the hardness and strength of the tungsten carbide alloy. Due to the relatively small particle size of tungsten carbide and molybdenum carbide in the matrix, when a crack propagates in the matrix, due to the relatively high hardness of tungsten carbide and molybdenum carbide, the propagation direction needs to change frequently, which increases the energy consumption during crack propagation, thereby improving the hardness, strength and toughness of the tungsten carbide alloy.

[0048] Alumina, as high-hardness ceramic particles, is evenly dispersed in the matrix. Through dispersion strengthening, it hinders dislocation movement, thereby improving the matrix's strength, hardness, and toughness. The ratio of alumina particle size to tungsten carbide in the matrix is ​​1:10. Dislocations moving to the alumina position must bypass the particles via a bowing mechanism, significantly increasing the energy consumption of dislocation movement and improving the matrix's strength and toughness.

[0049] Rare earth oxides can purify grain boundaries and inhibit the growth of tungsten carbide grains, improving the strength and toughness of the matrix through a fine grain strengthening mechanism. Rare earth oxides can also reduce the surface tension of molten copper, enhancing the copper's ability to wet ceramic particles and forming a uniform interface.

[0050] Copper has a relatively low melting point. During the plasma sintering process, copper melts, and copper atoms diffuse fully onto the surfaces of the tungsten carbide, molybdenum carbide, and alumina ceramic particles, reducing the porosity in the matrix. Copper's free electrons form metallic bonds with the unsaturated bonds on the ceramic particle surfaces. Due to the very small particle size and large surface area of ​​the copper powder, the contact sites between the copper and ceramic particles are increased, significantly improving the interfacial bonding strength. The copper and cobalt in the matrix form a continuous metal mesh at the interface. When a crack propagates at the interface between the hard particles and the matrix, the continuous metal mesh plastically deforms to bridge the crack, inhibiting crack penetration, improving the bond strength between the hard particles and the matrix, and reducing hard particle shedding. The energy absorption of cobalt and the bridging effect of copper interact to form a multi-level crack suppression mechanism, significantly enhancing the alloy's fracture resistance. Furthermore, copper acts as a "rigid node" in the metal mesh, restricting the plastic flow and softening deformation of cobalt at high temperatures, mitigating the strength loss caused by high-temperature softening of cobalt.

[0051] The preparation method of high wear-resistant tungsten carbide alloy comprises the following steps:

[0052] S1. Prepare hard particles.

[0053] The following steps are involved:

[0054] S11. Weigh tungsten carbide particles with a particle size of 150 nm to 200 nm, tungsten carbide particles with a particle size of 0.8 μm to 1.0 μm, and tungsten carbide particles with a particle size of 2 μm to 3 μm according to a mass ratio, and ultrasonically disperse the tungsten carbide particles in an ethanol medium for 1 to 3 hours to obtain composite tungsten carbide particles. Ultrasonic dispersion improves the uniformity of the dispersion of tungsten carbide particles of different particle sizes.

[0055] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 2-3 hours to remove moisture from the nano carbon black.

[0056] S13. Mix the composite tungsten carbide particles, nano-carbon black, cobalt powder, titanium powder, zirconium powder, and rare earth oxide according to a mass ratio and ball mill the mixture in an ethanol medium to obtain a mixed powder. The ball milling process uses cemented carbide balls with a ball-to-powder ratio of 6:1, a ball milling speed of 300-400 rpm, and a ball milling time of 12-24 hours.

[0057] S14. Dry the mixed powder in a vacuum drying oven at 60° C. for 12-24 hours, and maintain the mixed powder under a pressure of 50 MPa-100 MPa for 5-10 minutes to obtain a green body.

[0058] S15. Place the green body in a heating furnace for sintering, using argon gas as a protective layer during the sintering process. Cool naturally to room temperature to obtain a sintered product. The sintering temperature is 1400°C-1500°C, the sintering pressure is 10MPa-30MPa, and the holding time is 0.5h-1h.

[0059] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0060] S2. Ball mill tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, copper powder, and cobalt powder according to mass ratio in ethanol to obtain a matrix material. Carbide balls are used for the ball milling, with a ball-to-material ratio of 6:1, a ball milling speed of 300-400 rpm, and a ball milling time of 12-24 hours.

[0061] S3. Add the hard particles to the matrix raw material and ball mill until uniformly mixed to obtain a raw material powder. Use carbide balls for the mill, with a ball-to-material ratio of 6:1, a speed of 300-400 rpm, and a milling time of 12-24 hours. Dry the raw material powder in a vacuum drying oven at 60°C for 12-24 hours, then press into a raw material blank.

[0062] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0063] The sintering temperature is 1250° C.-1350° C., the sintering pressure is 30 MPa-50 MPa, and the sintering time is 20 min-30 min.

[0064] The spark plasma sintering furnace is used for sintering, which has the advantages of fast heating speed, short sintering time and low sintering temperature. It can be sintered at a lower temperature and in a shorter time to obtain a dense tungsten carbide alloy, effectively inhibit the growth of tungsten carbide alloy grains, obtain fine and uniform tungsten carbide grains, and improve the comprehensive performance of tungsten carbide alloy.

[0065] Example 1

[0066] A highly wear-resistant tungsten carbide alloy comprises a matrix and hard particles. The spherical hard particles are evenly distributed in the matrix, with the hard particles comprising 81% by weight and the matrix comprising 19% by weight. The hard particles comprise 78.5% by weight of composite tungsten carbide particles, 10% by weight of cobalt powder, 3% by weight of titanium powder, 2% by weight of zirconium powder, 0.5% by weight of rare earth oxide, and 6% by weight of nano-carbon black.

[0067] The composite tungsten carbide particles include the following components in percentage by mass: 15 wt.% of tungsten carbide particles with a particle size of 150 nm-200 nm, 65 wt.% of tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and 20 wt.% of tungsten carbide particles with a particle size of 2 μm-3 μm.

[0068] The matrix includes the following components in percentage by mass: 75.2 wt.% of tungsten carbide, 4 wt.% of molybdenum carbide, 4 wt.% of aluminum oxide, 0.3 wt.% of rare earth oxide, 0.5 wt.% of copper, and 16 wt.% of cobalt.

[0069] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0070] The preparation method of high wear-resistant tungsten carbide alloy comprises the following steps:

[0071] S1. Prepare hard particles.

[0072] The following steps are involved:

[0073] S11. Weigh tungsten carbide particles with a particle size of 150 nm-200 nm, tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and tungsten carbide particles with a particle size of 2 μm-3 μm according to a mass ratio, and ultrasonically disperse the tungsten carbide particles in an ethanol medium for 1 hour to obtain composite tungsten carbide particles.

[0074] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 2 hours to remove moisture from the nano carbon black.

[0075] S13. Composite tungsten carbide particles, nano-carbon black, cobalt powder, titanium powder, zirconium powder, and rare earth oxide are mixed according to a mass ratio and ball-milled in an ethanol medium to obtain a mixed powder. Carbide balls are used for the ball-to-powder milling, with a ball-to-powder ratio of 6:1, a ball-milling speed of 300 r / min, and a ball-milling time of 20 h.

[0076] S14. Dry the mixed powder in a vacuum drying oven at 60° C. for 12-24 hours, and maintain the mixed powder under a pressure of 50 MPa for 10 minutes to obtain a green body.

[0077] S15. Place the green body in a heating furnace for sintering, using argon as a protective gas during the sintering process. Cool naturally to room temperature to obtain a sintered product. The sintering temperature is 1400°C, the sintering pressure is 15 MPa, and the holding time is 1 hour.

[0078] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0079] S2. Ball mill tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, copper powder, and cobalt powder according to their mass ratio in ethanol to obtain a matrix material. Carbide balls were used for the milling process, with a ball-to-powder ratio of 6:1, a speed of 300 rpm, and a milling time of 20 hours.

[0080] S3. Add the hard particles to the matrix raw material and ball mill until uniformly mixed to obtain a raw material powder. Carbide balls are used for the milling process, with a ball-to-material ratio of 6:1, a speed of 300 rpm, and a milling time of 20 hours. The raw material powder is dried in a vacuum drying oven at 60°C for 12 hours and then pressed into a raw material blank.

[0081] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0082] The sintering temperature is 1300°C, the sintering pressure is 30 MPa, and the sintering time is 30 min.

[0083] Example 2

[0084] A highly wear-resistant tungsten carbide alloy comprises a matrix and hard particles. The spherical hard particles are evenly distributed in the matrix, with the hard particles comprising 85% by weight and the matrix comprising 15% by weight. The hard particles comprise 79.2% by weight of composite tungsten carbide particles, 6% by weight of cobalt powder, 2% by weight of titanium powder, 2% by weight of zirconium powder, 0.8% by weight of rare earth oxide, and 10% by weight of nano-carbon black.

[0085] The composite tungsten carbide particles include the following components in percentage by mass: 12 wt.% of tungsten carbide particles with a particle size of 150 nm-200 nm, 64 wt.% of tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and 24 wt.% of tungsten carbide particles with a particle size of 2 μm-3 μm.

[0086] The matrix includes the following components in percentage by mass: 75.8 wt.% of tungsten carbide, 4 wt.% of molybdenum carbide, 3 wt.% of aluminum oxide, 0.4 wt.% of rare earth oxide, 0.8 wt.% of copper, and 16 wt.% of cobalt.

[0087] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0088] The preparation method of high wear-resistant tungsten carbide alloy comprises the following steps:

[0089] S1. Prepare hard particles.

[0090] The following steps are involved:

[0091] S11. Weigh tungsten carbide particles with a particle size of 150 nm-200 nm, tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and tungsten carbide particles with a particle size of 2 μm-3 μm according to a mass ratio, and ultrasonically disperse the tungsten carbide particles in an ethanol medium for 1 h-3 h to obtain composite tungsten carbide particles.

[0092] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 2 hours to remove moisture from the nano carbon black.

[0093] S13. Composite tungsten carbide particles, nano-carbon black, cobalt powder, titanium powder, zirconium powder, and rare earth oxide are mixed according to a mass ratio and ball-milled in an ethanol medium to obtain a mixed powder. Carbide balls are used for the ball-to-powder milling, with a ball-to-powder ratio of 6:1, a ball-milling speed of 300 r / min, and a ball-milling time of 20 h.

[0094] S14. Dry the mixed powder in a vacuum drying oven at 60° C. for 12-24 hours, and maintain the mixed powder under a pressure of 70 MPa for 6 minutes to obtain a green body.

[0095] S15. Place the green body in a heating furnace for sintering, using argon as a protective gas during the sintering process. Cool naturally to room temperature to obtain a sintered product. The sintering temperature is 1500°C, the sintering pressure is 10 MPa, and the holding time is 1 hour.

[0096] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0097] S2. Ball mill tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, copper powder, and cobalt powder according to their mass ratio in ethanol to obtain a matrix material. Carbide balls were used for the milling process, with a ball-to-powder ratio of 6:1, a speed of 300 rpm, and a milling time of 20 hours.

[0098] S3. Add the hard particles to the matrix raw material and ball mill until uniformly mixed to obtain a raw material powder. Carbide balls are used for the milling process, with a ball-to-material ratio of 6:1, a speed of 300 rpm, and a milling time of 20 hours. The raw material powder is dried in a vacuum drying oven at 60°C for 12 hours and then pressed into a raw material blank.

[0099] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0100] The sintering temperature is 1250°C, the sintering pressure is 40 MPa, and the sintering time is 20 min.

[0101] Example 3

[0102] A highly wear-resistant tungsten carbide alloy comprises a matrix and hard particles. The spherical hard particles are evenly distributed in the matrix, with the hard particles comprising 85% by weight and the matrix comprising 15% by weight. The hard particles comprise 77.2% by weight of composite tungsten carbide particles, 8% by weight of cobalt powder, 3% by weight of titanium powder, 3% by weight of zirconium powder, 0.8% by weight of rare earth oxide, and 8% by weight of nano-carbon black.

[0103] The composite tungsten carbide particles include the following components in percentage by mass: 15 wt.% of tungsten carbide particles with a particle size of 150 nm-200 nm, 60 wt.% of tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and 25 wt.% of tungsten carbide particles with a particle size of 2 μm-3 μm.

[0104] The matrix includes the following components in percentage by mass: 74 wt.% of tungsten carbide, 5 wt.% of molybdenum carbide, 4 wt.% of aluminum oxide, 0.5 wt.% of rare earth oxide, 0.5 wt.% of copper, and 16 wt.% of cobalt.

[0105] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0106] The preparation method of high wear-resistant tungsten carbide alloy comprises the following steps:

[0107] S1. Prepare hard particles.

[0108] The following steps are involved:

[0109] S11. Weigh tungsten carbide particles with a particle size of 150 nm-200 nm, tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and tungsten carbide particles with a particle size of 2 μm-3 μm according to a mass ratio, and ultrasonically disperse the tungsten carbide particles in an ethanol medium for 2 hours to obtain composite tungsten carbide particles.

[0110] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 3 hours to remove moisture from the nano carbon black.

[0111] S13. Mix the composite tungsten carbide particles, nano-carbon black, cobalt powder, titanium powder, zirconium powder, and rare earth oxide according to a mass ratio and ball-mill the mixture in an ethanol medium to obtain a mixed powder. Carbide balls are used for the ball-to-powder milling, with a ball-to-powder ratio of 6:1, a ball-to-powder ratio of 400 rpm, and a ball-milling time of 20 hours.

[0112] S14. Dry the mixed powder in a vacuum drying oven at 60° C. for 12 h, and maintain the mixed powder under a pressure of 80 MPa for 10 min to obtain a green body.

[0113] S15. Place the green body in a heating furnace for sintering, using argon as a protective gas during the sintering process. Cool naturally to room temperature to obtain a sintered product. The sintering temperature is 1500°C, the sintering pressure is 20 MPa, and the holding time is 0.5 h.

[0114] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0115] S2. Ball mill tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, copper powder, and cobalt powder according to their mass ratio in ethanol to obtain a matrix material. Carbide balls were used for the milling process, with a ball-to-powder ratio of 6:1, a speed of 400 rpm, and a milling time of 20 hours.

[0116] S3. Add the hard particles to the matrix raw material and ball mill until uniformly mixed to obtain a raw material powder. Carbide balls are used for the milling process, with a ball-to-material ratio of 6:1, a speed of 400 rpm, and a milling time of 20 hours. The raw material powder is dried in a vacuum drying oven at 60°C for 12 hours and then pressed into a raw material blank.

[0117] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0118] The sintering temperature is 1350°C, the sintering pressure is 50 MPa, and the sintering time is 20 min.

[0119] Example 4

[0120] A highly wear-resistant tungsten carbide alloy comprises a matrix and hard particles. The spherical hard particles are evenly distributed in the matrix, with the hard particles comprising 85% by weight and the matrix comprising 15% by weight. The hard particles comprise 75% by weight of composite tungsten carbide particles, 10% by weight of cobalt powder, 2% by weight of titanium powder, 2% by weight of zirconium powder, 1% by weight of rare earth oxide, and 10% by weight of nano-carbon black.

[0121] The composite tungsten carbide particles include the following components in percentage by mass: 15 wt.% of tungsten carbide particles with a particle size of 150 nm-200 nm, 60 wt.% of tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and 25 wt.% of tungsten carbide particles with a particle size of 2 μm-3 μm.

[0122] The matrix includes the following components in percentage by mass: 74 wt.% of tungsten carbide, 5 wt.% of molybdenum carbide, 4 wt.% of aluminum oxide, 0.5 wt.% of rare earth oxide, 0.5 wt.% of copper, and 16 wt.% of cobalt.

[0123] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0124] The preparation method of high wear-resistant tungsten carbide alloy comprises the following steps:

[0125] S1. Prepare hard particles.

[0126] The following steps are involved:

[0127] S11. Weigh tungsten carbide particles with a particle size of 150 nm-200 nm, tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and tungsten carbide particles with a particle size of 2 μm-3 μm according to a mass ratio, and ultrasonically disperse the tungsten carbide particles in an ethanol medium for 2 hours to obtain composite tungsten carbide particles.

[0128] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 3 hours to remove moisture from the nano carbon black.

[0129] S13. Mix the composite tungsten carbide particles, nano-carbon black, cobalt powder, titanium powder, zirconium powder, and rare earth oxide according to a mass ratio and ball-mill the mixture in an ethanol medium to obtain a mixed powder. Carbide balls are used for the ball-to-powder milling, with a ball-to-powder ratio of 6:1, a ball-to-powder ratio of 400 rpm, and a ball-milling time of 20 hours.

[0130] S14. Dry the mixed powder in a vacuum drying oven at 60° C. for 12 h, and maintain the mixed powder under a pressure of 80 MPa for 10 min to obtain a green body.

[0131] S15. Place the green body in a heating furnace for sintering, using argon as a protective gas during the sintering process. Cool naturally to room temperature to obtain a sintered product. The sintering temperature is 1500°C, the sintering pressure is 20 MPa, and the holding time is 0.5 h.

[0132] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0133] S2. Ball mill tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, copper powder, and cobalt powder according to their mass ratio in ethanol to obtain a matrix material. Carbide balls were used for the milling process, with a ball-to-powder ratio of 6:1, a speed of 400 rpm, and a milling time of 20 hours.

[0134] S3. Add the hard particles to the matrix raw material and ball mill until uniformly mixed to obtain a raw material powder. Carbide balls are used for the milling process, with a ball-to-material ratio of 6:1, a speed of 400 rpm, and a milling time of 20 hours. The raw material powder is dried in a vacuum drying oven at 60°C for 12 hours and then pressed into a raw material blank.

[0135] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0136] The sintering temperature is 1350°C, the sintering pressure is 50 MPa, and the sintering time is 20 min.

[0137] Example 5

[0138] A highly wear-resistant tungsten carbide alloy comprises a matrix and hard particles. The spherical hard particles are evenly distributed in the matrix, with the hard particles comprising 85% by weight and the matrix comprising 15% by weight. The hard particles comprise 77.2% by weight of composite tungsten carbide particles, 8% by weight of cobalt powder, 3% by weight of titanium powder, 3% by weight of zirconium powder, 0.8% by weight of rare earth oxide, and 8% by weight of nano-carbon black.

[0139] The composite tungsten carbide particles include the following components in percentage by mass: 15 wt.% of tungsten carbide particles with a particle size of 150 nm-200 nm, 60 wt.% of tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and 25 wt.% of tungsten carbide particles with a particle size of 2 μm-3 μm.

[0140] The matrix includes the following components in percentage by mass: 70 wt.% of tungsten carbide, 6 wt.% of molybdenum carbide, 5 wt.% of aluminum oxide, 0.5 wt.% of rare earth oxide, 0.5 wt.% of copper, and 18 wt.% of cobalt.

[0141] The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

[0142] The preparation method of high wear-resistant tungsten carbide alloy comprises the following steps:

[0143] S1. Prepare hard particles.

[0144] The following steps are involved:

[0145] S11. Weigh tungsten carbide particles with a particle size of 150 nm-200 nm, tungsten carbide particles with a particle size of 0.8 μm-1.0 μm, and tungsten carbide particles with a particle size of 2 μm-3 μm according to a mass ratio, and ultrasonically disperse the tungsten carbide particles in an ethanol medium for 2 hours to obtain composite tungsten carbide particles.

[0146] S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 3 hours to remove moisture from the nano carbon black.

[0147] S13. Mix the composite tungsten carbide particles, nano-carbon black, cobalt powder, titanium powder, zirconium powder, and rare earth oxide according to a mass ratio and ball-mill the mixture in an ethanol medium to obtain a mixed powder. Carbide balls are used for the ball-to-powder milling, with a ball-to-powder ratio of 6:1, a ball-to-powder ratio of 400 rpm, and a ball-milling time of 20 hours.

[0148] S14. Dry the mixed powder in a vacuum drying oven at 60° C. for 12 h, and maintain the mixed powder under a pressure of 80 MPa for 10 min to obtain a green body.

[0149] S15. Place the green body in a heating furnace for sintering, using argon as a protective gas during the sintering process. Cool naturally to room temperature to obtain a sintered product. The sintering temperature is 1500°C, the sintering pressure is 20 MPa, and the holding time is 0.5 h.

[0150] S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

[0151] S2. Ball mill tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, copper powder, and cobalt powder according to their mass ratio in ethanol to obtain a matrix material. Carbide balls were used for the milling process, with a ball-to-powder ratio of 6:1, a speed of 400 rpm, and a milling time of 20 hours.

[0152] S3. Add the hard particles to the matrix raw material and ball mill until uniformly mixed to obtain a raw material powder. Carbide balls are used for the milling process, with a ball-to-material ratio of 6:1, a speed of 400 rpm, and a milling time of 20 hours. The raw material powder is dried in a vacuum drying oven at 60°C for 12 hours and then pressed into a raw material blank.

[0153] S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

[0154] The sintering temperature is 1350°C, the sintering pressure is 50 MPa, and the sintering time is 20 min.

[0155] Comparative Example 1

[0156] The difference between this comparative example and Example 3 is that the composite tungsten carbide particles of the hard particles in this comparative example only contain tungsten carbide particles with a particle size of 150 nm to 200 nm.

[0157] Comparative Example 2

[0158] The difference between this comparative example and Example 3 is that the composite tungsten carbide particles of the hard particles in this comparative example only contain tungsten carbide particles with a particle size of 2 μm-3 μm.

[0159] Comparative Example 3

[0160] The difference between this comparative example and Example 3 is that the hard particles in this comparative example do not contain zirconium powder and titanium powder, and the content of the composite tungsten carbide particles is 83.2 wt.%.

[0161] Comparative Example 4

[0162] The difference between this comparative example and Example 3 is that the substrate of this comparative example does not contain aluminum oxide, and the content of molybdenum carbide is 9 wt.%.

[0163] Comparative Example 5

[0164] The difference between this comparative example and Example 3 is that the substrate of this comparative example does not contain copper, and the content of cobalt is 16.5 wt.%.

[0165] The Rockwell hardness, fracture toughness, flexural strength, and wear loss of the tungsten carbide alloys prepared in Examples 1-5 and Comparative Examples 1-5 were tested. Fracture toughness was measured according to ISO 28079-2009, the standard for fracture toughness of cemented carbides; hardness was measured according to GBT 3849.1-2015, Rockwell Hardness of Cemented Carbides (A Scale), Part 1: Test Method; and flexural strength was measured using GBT 3851-2015, the method for determining transverse rupture strength of cemented carbides. Wear loss was calculated using Q / 62071126-8F0524-2014, "Determination of Abrasive Wear of Cemented Carbides." The properties of the tungsten carbide alloys prepared in Examples 1-5 and Comparative Examples 1-5 are shown in Table 1.

[0166] Table 1 Properties of tungsten carbide alloys prepared in Examples 1-5 and Comparative Examples 1-5

[0167]

[0168]

[0169] As can be seen from Table 1, using composite tungsten carbide particles inside hard particles and adding zirconium powder and titanium powder can effectively improve the fracture toughness, hardness, wear resistance and abrasion resistance of tungsten carbide alloy. Adding copper to the matrix can improve the fracture toughness and bending strength of tungsten carbide alloy, and alumina in the matrix can effectively improve the wear resistance, hardness, fracture toughness and bending strength of tungsten carbide alloy.

[0170] Therefore, the wear-resistant tungsten carbide alloy and its preparation method described in the present invention can solve the problem that the hardness and toughness of the existing tungsten carbide alloy cannot be synergistically enhanced, which affects the wear resistance of the tungsten carbide alloy.

[0171] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A highly wear-resistant tungsten carbide alloy, characterized by: The invention comprises a matrix and hard particles, wherein the spherical hard particles are uniformly distributed in the matrix, the mass percentage of the hard particles is 80wt.%-90wt.%, and the mass percentage of the matrix is ​​10wt.%-20wt.%; the hard particles comprise 75wt.%-80wt.% of composite tungsten carbide particles, 5wt.%-10wt.% of cobalt powder, 2wt.%-3wt.% of titanium powder, 2wt.%-3wt.% of zirconium powder, 0.5wt.%-1wt.% of rare earth oxide, and 5wt.%-10wt.% of nano carbon black.

2. The high wear-resistant tungsten carbide alloy according to claim 1, characterized in that: The composite tungsten carbide particles include the following components in percentage by mass: 10 wt.% to 15 wt.% of tungsten carbide particles with a particle size of 150 nm to 200 nm, 50 wt.% to 70 wt.% of tungsten carbide particles with a particle size of 0.8 μm to 1.0 μm, and 20 wt.% to 30 wt.% of tungsten carbide particles with a particle size of 2 μm to 3 μm.

3. The highly wear-resistant tungsten carbide alloy according to claim 2, characterized in that: The particle size of the cobalt powder is 3 μm-5 μm, the particle size of the titanium powder is 1 μm-2 μm, and the particle size of the zirconium powder is 1 μm-2 μm.

4. The highly wear-resistant tungsten carbide alloy according to claim 3, characterized in that: The particle size of the rare earth oxide is 0.5 μm-1.0 μm, and the rare earth oxide is one of cerium oxide and yttrium oxide.

5. The high wear-resistant tungsten carbide alloy according to claim 4, characterized in that: The matrix includes the following components in mass percentage: 70wt.%-80wt.% of tungsten carbide, 4wt.%-6wt.% of molybdenum carbide, 3wt.%-5wt.% of aluminum oxide, 0.1wt.%-0.5wt.% of rare earth oxide, 0.5wt.%-1wt.% of copper, and 15wt.%-20wt.% of cobalt.

6. The highly wear-resistant tungsten carbide alloy according to claim 5, characterized in that: The particle size of tungsten carbide in the matrix is ​​3μm-5μm, the particle size of molybdenum carbide is 0.8μm-1μm, the particle size of aluminum oxide is 0.2μm-0.4μm, the particle size of copper is 0.3μm-0.5μm, and the particle size of cobalt is 1μm-2μm; the particle size of rare earth oxide is 0.2μm-0.4μm, and the rare earth oxide is yttrium oxide.

7. The method for preparing a highly wear-resistant tungsten carbide alloy according to claim 6, wherein: The following steps are involved: S1, preparing hard particles; S2. Ball-milling tungsten carbide powder, molybdenum carbide powder, aluminum oxide powder, rare earth oxide powder, zirconium oxide powder, and copper powder in an ethanol medium according to a mass ratio to obtain a matrix raw material; S3, adding the hard particles to the matrix raw material and ball milling and mixing, and obtaining raw material powder after uniform mixing; drying the raw material powder and pressing it into raw material blanks; S4. Place the raw material blank into a plasma sintering furnace for sintering, and naturally cool to room temperature to obtain tungsten carbide alloy.

8. The method for preparing a highly wear-resistant tungsten carbide alloy according to claim 7, wherein: Said S1 comprises the following steps: S11, weighing tungsten carbide particles with a particle size of 150 nm to 200 nm, tungsten carbide particles with a particle size of 0.8 μm to 1.0 μm, and tungsten carbide particles with a particle size of 2 μm to 3 μm according to a mass ratio, and ultrasonically dispersing the tungsten carbide particles in an ethanol medium for 1 hour to 3 hours to obtain composite tungsten carbide particles; S12, drying the composite tungsten carbide particles; drying the nano carbon black at 120° C. for 2-3 hours to remove moisture from the nano carbon black; S13, mixing composite tungsten carbide particles, nano carbon black, cobalt powder, titanium powder, zirconium powder and rare earth oxide according to a mass ratio, and ball milling the mixture in an ethanol medium to obtain a mixed powder; S14, drying the mixed powder, and maintaining the mixed powder under a pressure of 50 MPa-100 MPa for 5 min-10 min to obtain a green body; S15, placing the green body into a heating furnace for sintering, using an inert gas for protection during the sintering process, and naturally cooling to room temperature to obtain a sintered product; S16. Crushing the sintered material, ball milling, and sieving to obtain hard particles with a particle size of 20 μm-30 μm.

9. The method for preparing a highly wear-resistant tungsten carbide alloy according to claim 8, wherein: In the above-mentioned S15, the sintering temperature is 1400° C.-1500° C., the sintering pressure is 10 MPa-30 MPa, and the holding time is 0.5 h-1 h.

10. The method for preparing a highly wear-resistant tungsten carbide alloy according to claim 9, wherein: In the above-mentioned S4, the sintering temperature is 1300° C.-1400° C., the sintering pressure is 30 MPa-50 MPa, and the sintering time is 20 min-30 min.

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