Multi-element hard metal wear-resistant ball and its application in heavy industry

Abstract

The application belongs to the field of metal materials, and provides a multi-element hard alloy wear-resistant ball and application thereof in heavy industry. The multi-element hard alloy wear-resistant ball adopts a cobalt-nickel-iron-chromium-molybdenum multi-element pre-alloy powder and a radial gradient core-shell composite structure, realizes the cooperation of outer layer high-hardness wear resistance and inner core high-toughness anti-crushing through the gradient design of the chromium-rich / molybdenum-rich nano precipitated phase reinforced binder phase, the vanadium carbide and graphite core-shell modified tungsten carbide hard phase, and the outer layer low-binder phase fine crystal and the inner core high-binder phase coarse crystal, solves the problems that the existing ball mill medium is difficult to consider high-hardness wear resistance and low-friction self-lubrication, the gradient structure residual stress and interface defect sensitivity, and the high-density non-capsule hot isostatic pressing process window is extremely narrow, and makes the wear-resistant ball have excellent performance of Vickers hardness HV1200-1600, compressive strength 4000-6000 MPa, density 14.0-15.3 g / cm 3 , and wide application value in the ore ball mill or semi-autogenous mill grinding medium.

Description

Technical Field

[0001] This invention relates to the field of metallic materials, specifically to a multi-component cemented carbide wear-resistant ball and its application in heavy industry. Background Technology

[0002] In heavy industries such as mining, building materials, cement, and power, ball mills and semi-autogenous mills are widely used as core crushing and grinding equipment for the fine crushing and grinding of solid materials such as ores, slurries, cement clinker, and coal powder. Grinding media balls, as a key consumable in ball mills, directly affect grinding efficiency, energy consumption, and production costs. Under high-intensity, high-frequency impact grinding conditions, grinding media balls need to simultaneously possess high hardness to resist abrasive wear, high toughness to resist impact crushing, high density to provide sufficient kinetic energy, and good corrosion resistance to adapt to wet grinding environments. Especially in the ultrafine grinding processes of hard rock ores and high-hardness minerals, the comprehensive performance requirements for grinding media balls are even more stringent. While traditional high-chromium cast iron balls are relatively inexpensive, their hardness and toughness are difficult to meet the requirements simultaneously, resulting in a short service life. Forged steel balls, while having good toughness, lack sufficient hardness, leading to rapid wear. Ceramic balls, although having high hardness, are brittle and easily broken, and their low density results in low grinding efficiency. Therefore, developing new grinding media balls that combine high hardness, high toughness, high density, and long service life is of great significance for improving the efficiency of crushing and grinding processes in heavy industry and reducing energy consumption and operating costs.

[0003] Existing grinding media mainly include high-chromium cast iron balls, forged steel balls, and traditional tungsten carbide-based cemented carbide balls. While high-chromium cast iron balls are inexpensive, their hardness is insufficient (HV600-HV800), leading to rapid wear and short lifespan in grinding high-hardness ores. Forged steel balls have good toughness but poor wear resistance, making them only suitable for coarse crushing. Traditional tungsten carbide-based cemented carbide balls have the advantage of high hardness, but they suffer from the following shortcomings: First, traditional cemented carbide uses a single cobalt-based binder phase, which is prone to selective dissolution of cobalt in corrosive media containing chloride and sulfate ions, such as ore slurries, leading to the shedding of the hard phase and increased wear. For example, Chinese patent CN203842646U discloses a wear-resistant steel ball for a ball mill with embedded cemented carbide blocks, but metal loss is severe in acidic ore slurries. Second, traditional cemented carbide has a homogeneous structure, making it difficult to simultaneously meet the contradictory requirements of high surface hardness and wear resistance with high internal toughness and impact resistance. For example, patent CN1044... Chinese patent 39248A discloses a method for preparing a gradient structure diamond cemented carbide composite ball tooth. However, the gradient formation depends on the natural diffusion of carbon concentration during sintering, the gradient layer thickness is poorly controlled, and the brittle phase enrichment in the transition zone leads to crack initiation. Thirdly, in the traditional cemented carbide preparation process, the interface bonding between the binder phase and the hard phase depends on the liquid phase wetting and solid solution-precipitation mechanism during sintering. However, there is a lack of active control over the chemical state of the interface, which makes the interface prone to peeling under high stress wear conditions. At the same time, the surface of the hard phase particles lacks strengthening and modification methods, and cannot form a wear-resistant protective layer structure. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-component cemented carbide wear-resistant ball and its application in heavy industry, which solves the problems of existing ball milling media, such as the difficulty in achieving high hardness and high wear resistance with low friction and self-lubrication, the coupling contradiction between residual stress and interface defect sensitivity between the wear resistance gain of the radial gradient fine-grained outer layer and the overall anti-fracture reliability, and the extremely narrow process window between achieving high density and low porosity under the design of high hard phase content and low binder phase in the outer layer and the manufacturing convenience of not needing a casing in the hot isostatic pressing densification process.

[0005] This invention achieves a triple synergistic design through the sintering of pre-alloyed powder of a multi-metal binder phase to form a nano-precipitated multi-metal binder phase, a vanadium carbide and graphite core-shell modified tungsten carbide hard phase, and a radial gradient structure with fine grains of the outer low-binding phase and coarse grains of the core high-binding phase. This results in dual enhancement of the high-temperature strength of the binder phase and the refinement of the hard phase grains to inhibit growth. This allows the multi-metal cemented carbide wear-resistant ball to maintain high hardness and wear resistance while also possessing high toughness and anti-fracture performance. Furthermore, the radial gradient structure optimizes stress distribution and reduces sensitivity to interface defects. Under conditions of high hard phase content, hot isostatic pressing densification without cladding is achieved, significantly improving manufacturing convenience and cost competitiveness.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A multi-component cemented carbide wear-resistant ball comprises the following components based on the total mass of the multi-component cemented carbide wear-resistant ball:

[0008] The hard phase is tungsten carbide, with a mass fraction of 81 wt% to 92 wt%.

[0009] The binder phase is a multi-metal binder phase with a mass fraction of 7 wt% to 18 wt%. The multi-metal binder phase is formed by sintering multi-metal binder phase pre-alloyed powder, which is prepared by alloying at least four metal elements selected from cobalt, nickel, iron, chromium and molybdenum.

[0010] The added phase comprises vanadium carbide, graphite, or a combination of vanadium carbide and graphite, wherein the mass fraction of vanadium carbide is 0 wt% to 1.0 wt%, the mass fraction of graphite is 0 wt% to 0.5 wt%, and the mass fraction of at least one of vanadium carbide and graphite is greater than 0 wt%.

[0011] The sum of the mass fractions of the hard phase, binder phase, vanadium carbide and graphite is 100 wt%.

[0012] Furthermore, the core-shell hard phase intermediate powder is a composite powder with tungsten carbide as the core and a shell layer containing vanadium carbide, graphite, or a mixture of vanadium carbide and graphite on its surface; the mass fraction of vanadium carbide in claim 1 is the percentage of the total mass of vanadium carbide in the multi-element hard alloy wear-resistant ball to the total mass of the multi-element hard alloy wear-resistant ball, wherein the total mass of vanadium carbide includes vanadium carbide in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide added in powder form; the mass fraction of graphite is the percentage of the total mass of graphite in the multi-element hard alloy wear-resistant ball to the total mass of the multi-element hard alloy wear-resistant ball, wherein the total mass of graphite includes graphite in the shell layer of the core-shell hard phase intermediate powder and graphite added in powder form.

[0013] The multi-component cemented carbide wear-resistant ball has an outer layer region and a core region along the radial direction. The outer layer region is the area extending radially inward from the outer surface of the multi-component cemented carbide wear-resistant ball, and the core region is the remaining area other than the outer layer region.

[0014] The multi-component hard alloy wear-resistant ball is made by sintering and hot isostatic pressing densification of a radial gradient spherical blank. The radial gradient spherical blank is made by assembling an outer layer mixed powder and a core mixed powder with the aid of a forming binder. Both the outer layer mixed powder and the core mixed powder contain multi-component metal binder phase pre-alloy powder and tungsten carbide, and at least part of the tungsten carbide in the outer layer mixed powder is a core-shell hard phase intermediate powder.

[0015] Furthermore, the multi-metal binder phase pre-alloyed powder is prepared through the following steps:

[0016] (A1) Raw material preparation: Select at least four of the following metal raw material powders: cobalt, nickel, iron, chromium, and molybdenum; in the multi-metal binder phase pre-alloyed powder, the atomic percentage of the selected metal elements shall be within the corresponding ranges: cobalt 5 at% to 40 at%, nickel 5 at% to 40 at%, iron 5 at% to 40 at%, chromium 5 at% to 30 at%, and molybdenum 5 at% to 30 at; for the unselected metal elements, the atomic percentage shall be 0 at%; and the sum of the atomic percentages of all metal elements shall be 100 at%.

[0017] (A2) Melting: Under vacuum conditions of 1 Pa to 50 Pa or under protective atmosphere conditions, the metal raw material powder obtained in step A1 is heated to 1500°C to 1700°C and held for 10 min to 60 min to obtain a uniform alloy melt; the protective atmosphere is argon atmosphere or nitrogen atmosphere.

[0018] (A3) Atomization powder preparation: Inert gas atomization is used, with argon or nitrogen as the atomizing gas and the atomization pressure is 2MPa to 8MPa to atomize the alloy melt and obtain multi-metal binder phase pre-alloyed powder.

[0019] (A4) Sieving and classifying: The multi-metal binder phase pre-alloyed powder obtained in step A3 is sieved to obtain multi-metal binder phase pre-alloyed powder with a particle size of 10μm to 75μm.

[0020] (A5) Oxygen content control: By controlling the vacuum degree, protective atmosphere purity and atomization parameters in steps A2 and A3, the oxygen content of the obtained multi-metal binder phase pre-alloyed powder is made to be 0.01wt% to 0.50wt%, wherein the oxygen content is measured by inert gas melting-infrared absorption method.

[0021] Furthermore, the core-shell hard phase intermediate powder is prepared through the following steps:

[0022] (B1) Raw material preparation: Tungsten carbide, vanadium carbide, and graphite are provided;

[0023] (B2) Proportion: Based on 100 parts by mass of tungsten carbide, 0.1 to 2.0 parts by mass of vanadium carbide and 0.05 to 0.50 parts by mass of graphite;

[0024] (B3) Coating and Mixing: Under a protective atmosphere, the raw materials described in step B1 are ball-milled and mixed according to the proportions described in step B2. The ball milling speed is 50 r / min to 300 r / min, the ball milling time is 1 h to 12 h, the ball-to-powder ratio is 2:1 to 10:1, the ball-to-powder ratio is the mass ratio of the ball milling media to the powder, the filling coefficient of the ball milling jar is 30% to 70%, the filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball milling jar to the inner volume of the ball milling jar, so that vanadium carbide and graphite adhere to the surface of tungsten carbide particles to obtain coated and mixed powder; the protective atmosphere is an argon atmosphere or a nitrogen atmosphere; the ball milling media is zirconium dioxide balls;

[0025] (B4) Heat treatment to form a shell: Under vacuum conditions of 1 Pa to 50 Pa or under protective atmosphere conditions, the coated mixed powder obtained in step B3 is heated to 800°C to 1100°C and held for 0.5 h to 3.0 h to obtain a core-shell hard phase intermediate powder.

[0026] (B5) Shell Parameter Control: By controlling the ball milling time and ball-to-material ratio in step B3 and the heat treatment temperature and time in step B4, the shell thickness of the obtained core-shell hard phase intermediate powder is 2 nm to 30 nm and the shell coverage is 80% to 100%. The shell thickness is confirmed by transmission electron microscopy, and the shell coverage is confirmed by scanning electron microscopy or transmission electron microscopy. The shell coverage is the percentage of particles with continuous shells to the total number of particles. A continuous shell refers to a shell that is continuously covered along the surface of the tungsten carbide particles without visible interruption in the microscopic image. The oxygen content of the core-shell hard phase intermediate powder is 0.01 wt% to 0.30 wt%.

[0027] Furthermore, the radially gradient spherical preform is prepared through the following steps:

[0028] (C1) Preparation of outer layer mixed powder: Based on a total mass of 100 parts by mass of the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 88.8 to 94 parts by mass of tungsten carbide, 6 to 10 parts by mass of multi-metal binder phase pre-alloyed powder, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.20 parts by mass of graphite, to obtain the outer layer mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the outer layer mixed powder, and all sources include vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form; at least part of the tungsten carbide in the outer layer mixed powder is core-shell hard phase intermediate powder;

[0029] (C2) Preparation of core-mixed powder: Based on a total mass of 100 parts by mass of core-mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core-mixed powder contains 78.5 to 88 parts by mass of tungsten carbide, 12 to 20 parts by mass of multi-metal binder phase pre-alloyed powder, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.50 parts by mass of graphite to obtain core-mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the core-mixed powder, and all sources include vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form;

[0030] (C3) Granulation: Add forming binder to the outer layer mixed powder and the core mixed powder respectively, the amount of which is 0.5wt% to 4.0wt% of the mass of each mixed powder, and mix at 60℃ to 120℃ for 0.5h to 3h to obtain the outer layer granulated powder and the core granulated powder respectively.

[0031] (C4) Radial assembly forming: The core granulated powder and the outer granulated powder are filled into the mold in sections. By controlling the filling amount of the outer granulated powder and the core granulated powder, the outer layer thickness is 0.10 times the radius R of the radial gradient spherical blank to 0.30 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. The blank is pressed with a pressure of 100MPa to 600MPa to obtain the radial gradient spherical blank.

[0032] (C5) Relative density control: The relative density of the radial gradient spherical preform is 50% to 70%. The relative density is the ratio of the measured density of the radial gradient spherical preform to its theoretical density calculated according to the formula of the outer layer mixed powder and the core mixed powder.

[0033] Furthermore, the molding adhesive is prepared through the following steps:

[0034] (D1) Raw material preparation: Provide paraffin wax and stearic acid;

[0035] (D2) Ratio: The mass ratio of paraffin to stearic acid is 5:1 to 20:1;

[0036] (D3) Mixing preparation: Paraffin wax and stearic acid are mixed at 60°C to 120°C for 0.5 h to 3 h to obtain a molding binder;

[0037] The multi-metal binder phase contains nano-precipitates with an equivalent diameter of 5 nm to 80 nm, which is the equivalent circle diameter measured in transmission electron microscopy (TEM) images. The nano-precipitates are at least one of a chromium-rich phase and a molybdenum-rich phase. The nano-precipitates are characterized by TEM combined with energy dispersive spectroscopy (EDS), and the atomic fraction of the enriched elements in the nano-precipitates is higher than that of the corresponding elements in the multi-metal binder phase. The density of the multi-component cemented carbide wear-resistant ball is 14.0 g / cm³ to 15.3 g / cm³. 3 .

[0038] Furthermore, the thickness of the outer layer is from 0.10 times the radius R of the multi-component cemented carbide wear-resistant ball to 0.30 times the radius R of the multi-component cemented carbide wear-resistant ball, where R is the radius of the multi-component cemented carbide wear-resistant ball;

[0039] Based on the mass of the outer layer region, the mass fraction of the multi-metal binder phase is 6 wt% to 10 wt%; based on the mass of the core region, the mass fraction of the multi-metal binder phase is 12 wt% to 20 wt%.

[0040] The average grain size of tungsten carbide in the outer region is 0.20 μm to 0.60 μm, and the average grain size of tungsten carbide in the core region is 0.80 μm to 1.50 μm. The average grain size was measured by the line section method in the microscopic image after polishing the cross section of the multi-component cemented carbide wear-resistant ball.

[0041] The diameter of the multi-component cemented carbide wear-resistant balls ranges from 5mm to 150mm.

[0042] As a concept of this invention, the present invention employs a synergistic design of multi-metal binder phase pre-alloyed powder and core-shell hard phase intermediate powder, primarily to enhance the high-temperature strength, toughness, and wear resistance of multi-metal cemented carbide wear-resistant balls. The multi-metal binder phase pre-alloyed powder is prepared by alloying at least four metal elements selected from cobalt, nickel, iron, chromium, and molybdenum through vacuum induction melting and inert gas atomization processes. Compared to traditional single cobalt binder phases, the multi-metal pre-alloyed powder maintains a uniform distribution of each metal element during sintering, avoiding element segregation and compositional fluctuations. After sintering, nanoscale chromium-rich or molybdenum-rich precipitates are formed in the multi-metal binder phase. These nano-precipitates significantly improve the high-temperature strength and softening resistance of the binder phase through a second-phase strengthening mechanism. Simultaneously, the addition of iron reduces dependence on scarce cobalt resources, and the addition of nickel enhances the toughness and corrosion resistance of the binder phase. The synergistic effect of multiple elements enables the binder phase to maintain high toughness while possessing resistance to deformation under high temperature and high stress. A vanadium carbide-graphite composite shell layer with a thickness of 2 nm to 30 nm was constructed on the surface of tungsten carbide particles through ball milling and heat treatment. Vanadium carbide in the shell layer acts as a grain growth inhibitor, hindering tungsten carbide grain boundary migration during sintering and achieving a fine-grained structure of 0.20 μm to 0.60 μm in the outer layer. This fine-grained strengthening effect significantly improves the hardness and wear resistance of the outer layer. At high temperatures, graphite in the shell layer partially dissolves into the binder phase to form solid-solution carbon, optimizing the wettability and interfacial bonding strength between the binder and hard phases. Simultaneously, the remaining graphite acts as a solid lubricant during friction, reducing the coefficient of friction and wear rate. The dual effect of the multi-component pre-alloyed powder strengthening the binder phase and the core-shell structure refining the hard phase enables multi-component cemented carbide wear-resistant balls to achieve an excellent balance between high hardness (HV1200 to HV1600) and high toughness (4000 MPa to 6000 MPa) under conditions of high hard phase content (81 wt% to 92 wt%).

[0043] This invention also discloses a method for preparing a multi-component cemented carbide wear-resistant ball, comprising the following steps:

[0044] (S1) Provide multi-metal binder phase pre-alloyed powder: Obtain multi-metal binder phase pre-alloyed powder, wherein for at least four of the selected metal elements cobalt, nickel, iron, chromium and molybdenum, their atomic percentages are within the corresponding ranges: cobalt is 5 at% to 40 at%, nickel is 5 at% to 40 at%, iron is 5 at% to 40 at%, chromium is 5 at% to 30 at%, and molybdenum is 5 at% to 30 at, and for the unselected metal elements, their atomic percentages are 0 at%, and the sum of the atomic percentages of all metal elements is 100 at, and the particle size is 10 μm to 75 μm;

[0045] (S2) Powder preparation and zone mixing: Based on a total mass of 100 parts by mass of the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 88.8 to 94 parts by mass of tungsten carbide, 6 to 10 parts by mass of the multi-metal binder phase pre-alloyed powder provided in step S1, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.20 parts by mass of graphite, to obtain the outer layer mixed powder; Based on a total mass of 100 parts by mass of the core mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core mixed powder contains 78.5 to 88 parts by mass of tungsten carbide, 12 to 20 parts by mass of the multi-metal binder phase pre-alloyed powder provided in step S1, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.50 parts by mass of graphite, to obtain the core mixed powder;

[0046] (S3) Granulation and radial assembly forming: Add forming binder to the outer layer mixed powder and the core mixed powder respectively, the amount of which is 0.5wt% to 4.0wt% of the mass of each mixed powder, and mix at 60℃ to 120℃ for 0.5h to 3h to obtain outer layer granulated powder and core granulated powder respectively; fill the core granulated powder and outer layer granulated powder into the mold in sections, and control the filling amount of the outer layer granulated powder and core granulated powder to make the outer layer thickness 0.10 times the radius R of the radial gradient spherical blank to 0.30 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank, and press with a pressure of 100MPa to 600MPa to obtain the radial gradient spherical blank;

[0047] (S4) Degreasing: Under vacuum conditions of 1 Pa to 200 Pa or under protective atmosphere conditions, the radial gradient spherical blank is heated to 200°C to 600°C and held for 0.5 h to 5 h to degrease, so that the removal rate of the forming binder reaches 90% to 100%, and the protective atmosphere is argon atmosphere or nitrogen atmosphere.

[0048] (S5) Sintering: Under vacuum conditions of 0.1 Pa to 50 Pa, the degreased spherical blank is heated to 1350°C to 1500°C and held for 0.5 h to 3 h for sintering;

[0049] (S6) Hot isostatic pressing densification treatment: The sintered spherical blank is subjected to hot isostatic pressing densification treatment under argon atmosphere at a temperature of 1300℃ to 1450℃, a pressure of 50MPa to 150MPa, and a time of 0.5h to 3h to obtain multi-component hard alloy wear-resistant balls.

[0050] Furthermore, the mixing in step S2 is performed using mechanical mixing or ball milling. When ball milling is used, the ball milling speed is 50 r / min to 300 r / min, the ball milling time is 1 h to 12 h, the ball-to-powder ratio is 2:1 to 10:1 (the ball-to-powder ratio is the mass ratio of the ball milling media to the powder), the filling coefficient of the ball mill jar is 30% to 70% (the filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball mill jar to the inner volume of the ball mill jar), and the ball milling is performed using dry ball milling, with zirconia balls as the ball milling media. When mechanical mixing is used, the mixing time is 1 h to 12 h.

[0051] In step S4, the removal rate is calculated using the following formula: Removal rate = (M1-M2) / M0×100%; where M1 is the mass of the spherical blank before degreasing, M2 is the mass of the spherical blank after degreasing, M0 is the theoretical mass of the forming binder added to the spherical blank before degreasing, and M0 is calculated based on the amount of forming binder added in step S3.

[0052] The vacuum sintering process in step S5 adopts the following heating curve: heating from room temperature to 1000℃ to 1200℃ at a heating rate of 5℃ / min to 15℃ / min and holding for 0.5h to 2h, then heating to 1350℃ to 1500℃ at a heating rate of 3℃ / min to 10℃ / min and holding for 0.5h to 3h.

[0053] In the hot isostatic pressing densification process in step S6, the sintered spherical blank does not need to be wrapped and can be directly subjected to hot isostatic pressing densification.

[0054] The absolute value of the diameter deviation of the obtained multi-component cemented carbide wear-resistant ball after grinding or polishing is no greater than 0.5 mm.

[0055] This invention also discloses the application of a multi-component cemented carbide wear-resistant ball in heavy industry. The application includes ores, slurries, or industrial slurries containing solid particles. The multi-component cemented carbide wear-resistant ball is used as a grinding media in ball mills or semi-autogenous mills.

[0056] Furthermore, the Vickers hardness of the multi-component cemented carbide wear-resistant ball is HV1200 to HV1600, which is measured under a load of 9.8N and a holding time of 10s to 15s.

[0057] Furthermore, the compressive strength of the multi-component cemented carbide wear-resistant ball is 4000MPa to 6000MPa, and the compressive strength is determined according to the ISO4506:2018 standard.

[0058] Furthermore, the ball milling media used in preparing the core-shell hard phase intermediate powder are zirconia balls with a diameter of 3 mm to 20 mm.

[0059] Furthermore, the melting in step A2 is carried out using a vacuum induction melting furnace or a vacuum arc melting furnace, and the crucible material is a graphite crucible or a water-cooled copper crucible.

[0060] Furthermore, the particle size of the metal raw material powder in step A1 is 10 μm to 150 μm.

[0061] Furthermore, the melting temperature in step A2 is determined based on the liquidus temperature of the alloy system. The temperature is heated to 20°C to 200°C above the liquidus temperature and held at that temperature. The liquidus temperature is determined by phase diagram or differential scanning calorimetry.

[0062] Furthermore, the degreasing process in step S4 adopts the following heating curve: heating from room temperature to 200℃ to 300℃ at a heating rate of 1℃ / min to 10℃ / min and holding at that temperature for 0.5h to 2h, then heating to 400℃ to 600℃ at a heating rate of 1℃ / min to 10℃ / min and holding at that temperature for 0.5h to 3h.

[0063] Furthermore, after the hot isostatic pressing densification treatment in step S6, the temperature is cooled to 500°C to 900°C at a cooling rate of 0.5°C / min to 10°C / min and held for 0.5h to 5h.

[0064] Furthermore, after sintering in step S5, the relative density of the spherical blank is 92% to 98%.

[0065] Furthermore, in step S6, when the relative density of the sintered spherical blank is not less than 98%, the sintered spherical blank can be directly subjected to hot isostatic pressing densification treatment without the need for a casing.

[0066] Furthermore, after granulation in step C3, the particles are cooled to room temperature and then sieved to achieve a particle size of 0.10 mm to 2.00 mm.

[0067] Furthermore, in step A4, the particle size is a volume distribution D10 of not less than 10 μm and D90 of not more than 75 μm, and D10 and D90 are measured by a laser particle size analyzer.

[0068] Furthermore, the atomic fraction of enriched elements in the nanoprecipitated phase is at least 5 at higher than the atomic fraction of the corresponding elements in the multi-metal binder phase.

[0069] Furthermore, the paraffin wax in the forming binder has a melting point of 52°C to 58°C, and the purity of stearic acid is not less than 95%.

[0070] Furthermore, the shell coverage was tested using a scanning electron microscope or a transmission electron microscope, with at least 5 fields of view randomly selected and at least 100 particles counted.

[0071] Furthermore, the theoretical density in the relative density is calculated based on the volume-weighted average density of the outer and inner regions. The volume of the outer region is calculated based on the outer layer thickness, and the volume of the inner region is the total volume of the spherical blank minus the volume of the outer region.

[0072] Furthermore, the actual density was determined using the Archimedes water displacement method, with anhydrous ethanol or kerosene as the impregnation medium.

[0073] Furthermore, during the smelting process in step A2, the heating rate is from 5°C / min to 50°C / min, and the amount of material fed at one time is from 100g to 5000g.

[0074] Furthermore, during the atomization process in step A3, the atomizing gas flow rate is 200 L / min to 1000 L / min, or the gas-liquid mass ratio is 2:1 to 8:1, the nozzle diameter is 2 mm to 8 mm, and the alloy melt temperature is controlled 50°C to 200°C above its liquidus temperature.

[0075] Furthermore, when preparing core-shell hard phase intermediate powder, a planetary ball mill or a drum ball mill is used, with the ball mill jar speed or the planetary ball mill revolution speed being 50 r / min to 300 r / min.

[0076] Furthermore, in the heat treatment process of step B4, the temperature is raised to 800°C to 1100°C at a heating rate of 5°C / min to 20°C / min and held for 0.5h to 3.0h, and then furnace cooled to room temperature at a cooling rate of no more than 10°C / min.

[0077] Furthermore, in the granulation process of step C3, the mixing method is heating and stirring or kneading and mixing. After mixing, the mixture is cooled to room temperature and then sieved and granulated.

[0078] Furthermore, in the radial assembly forming process of step C4, a spherical mold is used. First, the core granulated powder is filled in the center of the mold, and then the outer layer granulated powder is filled in the outer layer. Then, uniaxial pressing or cold isostatic pressing is performed at a pressure of 100MPa to 600MPa, and the pressure is held for 10s to 60s.

[0079] Furthermore, in the hot isostatic pressing densification process of step S6, the temperature is first raised to 1300°C to 1450°C under normal pressure, and then the pressure is raised to 50MPa to 150MPa. The temperature and pressure are maintained for 0.5h to 3h, and then the temperature is cooled to 500°C to 900°C at a cooling rate of 0.5°C / min to 10°C / min and held for 0.5h to 5h. Finally, the temperature is furnace cooled to room temperature.

[0080] Furthermore, the protective atmosphere used in steps B3 and B4 has a purity of not less than 99.9% and an oxygen content of not more than 100 ppm.

[0081] Furthermore, in the outer layer mixed powder, the core-shell structure modified tungsten carbide powder accounts for 30wt% to 100wt% of the total tungsten carbide.

[0082] As another concept of this invention, the radial gradient structure design of the outer layer with a low-binding phase and a coarse-grained core with a high-binding phase is mainly used to enhance the radial wear resistance gradient performance and overall fracture resistance reliability of the multi-component cemented carbide wear-resistant ball. The outer layer has a binder phase mass fraction of 6wt% to 10wt%, which, combined with the grain-refining effect of the core-shell hard phase intermediate powder, controls the average grain size of the outer tungsten carbide to be between 0.20μm and 0.60μm. The synergistic effect of the grain-refining reinforcement and the low-binding phase gives the outer layer an ultra-high hardness of HV1400 to HV1600, providing excellent wear resistance under high-frequency impact grinding conditions in a ball mill. The core region has a binder phase mass fraction of 12wt% to 20wt%. The high binder phase content appropriately coarsens the average grain size of the core tungsten carbide to 0.80μm to 1.50μm. The synergistic effect of the coarse-grained structure and the high binder phase content endows the core region with excellent plastic deformation capacity and crack propagation resistance, absorbing energy under impact loads and avoiding brittle fracture. The radial gradient structure is achieved through partitioned filling of the outer layer and the core layer of mixed powder and powder metallurgy forming. The outer layer thickness is controlled between 0.10R and 0.30R to ensure sufficient wear allowance during ball milling media use, while avoiding excessive outer layer thickness that would prevent the core's toughness advantage from being fully utilized. A metallurgical interface is formed between the outer layer and the core through sintering diffusion. The liquid-phase sintering mechanism of the multi-metal binder phase during sintering promotes interdiffusion of interfacial elements, eliminating porosity and microcracks at the gradient interface. The interfacial bonding strength is close to the matrix strength, avoiding the risk of delamination failure caused by weak interfacial bonding in traditional gradient materials. Furthermore, the gradually transitioning stress distribution from the outside to the inside generated during the sintering of the spherical preform by the radial gradient structure avoids stress concentration caused by differences in binder phase content in homogeneous structures, reducing the tendency for microcrack initiation caused by residual stress. In hot isostatic pressing densification, the outer layer's low-binding phase and high-hardness phase design enables it to have self-supporting capabilities, while the core's high-binding phase design allows the core to maintain good plasticity under high temperature and pressure. This allows the spherical preform to achieve a density increase from 92% to 98% after sintering to over 98% through hot isostatic pressing without the need for a casing. This simplifies the manufacturing process, reduces costs, and avoids the risk of contamination from impurities introduced by the casing material.

[0083] The synergistic effect of the multi-metal binder pre-alloyed powder and the core-shell hard phase intermediate powder in this invention is mainly reflected in the dual mechanisms of binder phase strengthening and hard phase refinement. The multi-metal binder pre-alloyed powder focuses on improving the high-temperature strength, toughness, and softening resistance of the binder phase through multi-element alloying and nano-precipitation strengthening. Cobalt provides basic toughness, nickel enhances corrosion resistance and low-temperature toughness, iron reduces costs and provides a certain strength, and chromium and molybdenum precipitate chromium-rich or molybdenum-rich nano-precipitates after sintering, significantly improving the high-temperature strength of the binder phase through a second-phase strengthening mechanism. The core-shell hard phase intermediate powder focuses on achieving grain refinement and tribological property optimization of the hard phase through the inhibition of vanadium carbide grain growth and the lubrication effect of graphite interface. The vanadium carbide shell inhibits tungsten carbide grain boundary migration during sintering to achieve a fine-grained structure, and the graphite shell optimizes the interfacial wettability between the binder phase and the hard phase and provides solid lubrication. The synergistic effect of the two is manifested in the following ways: the high-strength and high-toughness binder phase reinforced by the multi-component pre-alloy powder provides a tough bonding matrix for the fine-grained hard phase, preventing the hard phase from detaching under high stress due to insufficient binder phase strength; the core-shell structure-refined hard phase provides a uniformly distributed reinforcing skeleton for the binder phase, preventing local softening caused by binder phase aggregation in the coarse-grained structure; the addition of vanadium carbide and graphite further optimizes the carbon content and interfacial bonding state of the binder phase, producing a synergistic wetting effect with the multi-element composition of the multi-component pre-alloy powder, enabling the binder phase to fully wet the surface of the hard phase during sintering, eliminating porosity and microcracks, and achieving high density and high interfacial bonding strength. This dual synergistic mechanism of binder phase reinforcement and hard phase refinement enables the multi-component cemented carbide wear-resistant ball to simultaneously achieve high hardness of HV1200 to HV1600, high compressive strength of 4000MPa to 6000MPa, and excellent wear life under conditions of high hard phase content of 81wt% to 92wt%.

[0084] Beneficial technical effects

[0085] Significantly improves the high-temperature strength and softening resistance of the binder phase: A multi-metal binder phase reinforced by nano-precipitation phase is formed by sintering pre-alloyed powders of cobalt, nickel, iron, chromium and molybdenum. The chromium-rich or molybdenum-rich nano-precipitation phase effectively improves the high-temperature strength and softening resistance of the binder phase through the second-phase strengthening mechanism, avoiding the softening and hard phase shedding problems of traditional single cobalt binder phase under high-temperature grinding conditions. At the same time, the synergistic effect of multiple elements enables the binder phase to maintain high toughness while possessing the ability to resist deformation under high temperature and high stress, thus achieving comprehensive optimization of the binder phase performance.

[0086] Achieving dual functions of hard phase grain refinement and interfacial lubrication: Through the design of core-shell hard phase intermediate powder, a vanadium carbide and graphite composite shell is constructed on the surface of tungsten carbide particles. During sintering, vanadium carbide acts as a grain growth inhibitor, significantly refining the tungsten carbide grains in the outer layer to 0.20μm to 0.60μm. The grain refinement effect greatly improves the hardness and wear resistance of the outer layer. At the same time, graphite optimizes the interfacial wettability and bonding strength between the binder phase and the hard phase at high temperatures, and plays a solid lubricating role during friction, reducing the friction coefficient and wear rate, thus achieving an organic combination of wear resistance and self-lubrication.

[0087] Optimizing stress distribution and fracture resistance through a radial gradient structure: By designing a radial gradient structure with a fine-grained low-binding phase in the outer layer and a coarse-grained high-binding phase in the core, the high-hardness wear-resistant outer layer provides excellent wear life, while the high-toughness core layer provides excellent impact resistance and fracture resistance. The radial gradient stress distribution avoids stress concentration in homogeneous structures, reducing the tendency for microcrack initiation caused by residual stress. Simultaneously, the metallurgical bonding interface formed by sintering diffusion between the outer layer and the core eliminates the risk of interface delamination in traditional gradient materials, achieving a synergistic improvement in wear resistance and reliability.

[0088] Achieving unencased hot isostatic pressing densification with high hard phase content: By designing a low-binding phase and high-hard phase in the outer layer to provide self-supporting capabilities, and a high-binding phase in the core to provide high-temperature plastic flowability, radial gradient spherical preforms can achieve a density increase from 92% to 98% to over 98% without encasing under conditions of 81wt% to 92wt% high hard phase content through hot isostatic pressing densification. This significantly simplifies the manufacturing process, reduces production costs, avoids the risk of contamination from impurities introduced by encasing materials, and improves product quality stability and manufacturing convenience.

[0089] Achieving high-performance multi-component cemented carbide wear-resistant balls: Through a triple synergistic design of strengthening the binder phase with multi-component pre-alloyed powder, refining the hard phase with a core-shell structure, and optimizing stress distribution with a radial gradient structure, multi-component cemented carbide wear-resistant balls possess Vickers hardness of HV1200 to HV1600, compressive strength of 4000MPa to 6000MPa, and density of 14.0 g / cm³. 3 Up to 15.3 g / cm 3 Its excellent comprehensive performance demonstrates outstanding advantages such as high wear resistance, high fracture resistance, and high grinding efficiency in heavy industrial ball mills or semi-autogenous mills for grinding ores, slurries, and cement clinkers, significantly reducing the media consumption cost and total cost of ownership per unit of grinding product. Attached Figure Description

[0090] Figure 1 X-ray diffraction phase analysis diagrams of pre-alloyed powders for multi-metal binder phases and nano-precipitated phase reinforcement.

[0091] Figure 2 XPS full spectrum of surface chemical state analysis by X-ray photoelectron spectroscopy for the preparation of pre-alloyed powder for multi-metal binder phase and nano-precipitated phase reinforcement.

[0092] Figure 3 High-resolution X-ray photoelectron spectroscopy (XPS) spectrum of Cr 2p for the preparation of pre-alloyed powder for multi-metal binder phase and the strengthening of nano-precipitates.

[0093] Figure 4 High-resolution X-ray photoelectron spectroscopy (XPS) spectrum of Mo 3d for the preparation of pre-alloyed powder for multi-metal binder phase and reinforcement by nano-precipitates.

[0094] Figure 5 Transmission electron microscopy combined with energy dispersive spectroscopy (EDS) characterization of nanoprecipitates is presented in the form of transmission electron microscopy (TEM) combined with energy dispersive spectroscopy (EDS) for the preparation of pre-alloyed powders for multi-metal binder phases and the reinforcement of nanoprecipitates.

[0095] Figure 6 Raman spectra of vanadium carbide with a graphite shell were designed for core-shell hard phase intermediate powder.

[0096] Figure 7 Scanning electron microscopy (SEM) characterization of radial grain size gradient for a radially gradient spherical preform structure, featuring a fine-grained outer layer for high hardness and a coarse-grained inner core for high toughness.

[0097] Figure 8 The radial elemental distribution gradient of the spherical preform structure was characterized by an outer layer of fine-grained high-hardness and a core of coarse-grained high-toughness using electron probe microscopy, and the Co element line scan distribution map was obtained.

[0098] Figure 9 The radial elemental distribution gradient characterization of Ni element was obtained by electron probe microanalysis to design a radial gradient spherical preform structure with a fine-grained outer layer for high hardness and a coarse-grained inner core for high toughness.

[0099] Figure 10 The design of a radially gradient spherical preform structure was based on electron probe microanalysis of the radial elemental distribution gradient, characterized by a fine-grained outer layer with high hardness and a coarse-grained inner core with high toughness. The line scan distribution map of Fe element was obtained.

[0100] Figure 11 The radial elemental distribution gradient of the radial gradient spherical preform structure was characterized by the outer layer of fine-grained high-hardness and the inner core of coarse-grained high-toughness, and the Cr elemental line scan distribution map was obtained by electron probe microanalysis.

[0101] Figure 12 Electron probe microscopy was used to characterize the radial elemental distribution gradient of a radially gradient spherical preform structure, which features a fine-grained outer layer for high hardness and a coarse-grained inner core for high toughness. The result is a line scan distribution map of the Mo element.

[0102] Figure 13 Line scan distribution of total elements Co, Ni, Fe, Cr, and Mo was obtained by electron probe microanalysis to characterize the radial elemental distribution gradient of the radial gradient spherical preform structure, which features a fine-grained outer layer with high hardness and a coarse-grained inner core with high toughness.

[0103] Figure 14 This is a scanning electron microscope (SEM) image of the morphology of the pre-alloyed powder of the multi-metal binder phase in Example 1.

[0104] Figure 15 The image shows a scanning electron microscope (SEM) image of the surface morphology of the core-shell hard phase intermediate powder of Example 1.

[0105] Figure 16 The images shown are transmission electron microscopy (TEM) images of the microstructure of the cemented carbide sintered body in Example 1. (a) is a bright-field image of the cross-sectional morphology of the WC core-shell layer, (b) is a bright-field image of the morphology of the nano-precipitated phase in the binder phase, (c) is a STEM-EDS surface scan image of the Cr element distribution in the binder phase region, and (d) is a STEM-EDS surface scan image of the Mo element distribution in the binder phase region. Detailed Implementation

[0106] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Example

[0107] This embodiment provides a method for preparing a multi-component cemented carbide wear-resistant ball, including the following steps:

[0108] Step A: Preparation of pre-alloyed powder of multi-metal binder phase

[0109] (A1) Raw material preparation: Five metals, namely cobalt, nickel, iron, chromium and molybdenum, were selected as metal raw material powders with a particle size of 50 μm. In the multi-metal binder phase pre-alloyed powder, the atomic percentages of cobalt, nickel, iron, chromium and molybdenum were 20 at%, 25 at%, 15 at%, and 15 at%, respectively, and the sum of the atomic percentages of all metal elements was 100 at%.

[0110] (A2) Melting: Under vacuum conditions of 25 Pa, the metal raw material powder obtained in step A1 is heated to 1600℃ and held for 35 min to obtain a uniform alloy melt; a vacuum induction melting furnace is used for melting, the crucible material is a graphite crucible, the heating rate is 20℃ / min, the single feed amount is 1500g, and the melting temperature is determined according to the liquidus temperature of the alloy system, and heated to 100℃ above the liquidus temperature;

[0111] (A3) Atomization powder preparation: Inert gas atomization is adopted, with argon as the atomizing gas, atomization pressure of 5MPa, atomization gas flow rate of 500L / min, nozzle diameter of 5mm, and alloy melt temperature controlled 120℃ above its liquidus temperature. The alloy melt is atomized to obtain multi-metal binder phase pre-alloyed powder.

[0112] (A4) Sieving and classifying: The multi-metal binder phase pre-alloyed powder obtained in step A3 is sieved to obtain multi-metal binder phase pre-alloyed powder with a particle size of 10μm to 75μm, wherein the volume distribution D10 is 15μm and D90 is 70μm.

[0113] (A5) Oxygen content control: By controlling the vacuum degree, protective atmosphere purity and atomization parameters in steps A2 and A3, the oxygen content of the obtained multi-metal binder phase pre-alloyed powder is 0.25wt%, wherein the oxygen content is measured by inert gas melting-infrared absorption method.

[0114] Step B: Preparation of core-shell hard phase intermediate powder

[0115] (B1) Raw material preparation: Tungsten carbide, vanadium carbide, and graphite are provided;

[0116] (B2) Proportion: Based on 100 parts by mass of tungsten carbide, 1.0 parts by mass of vanadium carbide and 0.25 parts by mass of graphite;

[0117] (B3) Coating and mixing: Under an argon atmosphere, the raw materials described in step B1 are ball-milled and mixed according to the proportions described in step B2. The ball milling speed is 175 r / min, the ball milling time is 6.5 h, the ball-to-powder ratio is 6:1, the ball-to-powder ratio is the mass ratio of the ball milling media to the powder, and the filling coefficient of the ball milling jar is 50%. The filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball milling jar to the inner volume of the ball milling jar. This allows vanadium carbide and graphite to adhere to the surface of tungsten carbide particles, resulting in coated and mixed powder. The ball milling media are 10 mm diameter zirconium dioxide balls, and a planetary ball mill is used with a revolution speed of 175 r / min.

[0118] (B4) Heat treatment to form a shell: Under vacuum conditions of 25 Pa, the coated mixed powder obtained in step B3 is heated to 950 °C at a heating rate of 10 °C / min and held at that temperature for 1.75 h. Then it is furnace cooled to room temperature at a cooling rate of 8 °C / min to obtain a core-shell hard phase intermediate powder.

[0119] (B5) Shell Parameter Control: By controlling the ball milling time and ball-to-material ratio in step B3 and the heat treatment temperature and time in step B4, the shell thickness of the obtained core-shell hard phase intermediate powder is 16 nm and the shell coverage is 90%. The shell thickness is confirmed by transmission electron microscopy, and the shell coverage is confirmed by scanning electron microscopy. Eight fields of view are randomly selected and 150 particles are counted. The shell coverage is the percentage of particles with continuous shells to the total number of counted particles. A continuous shell refers to a shell that is continuously covered along the surface of the tungsten carbide particle without visible interruption in the microscopic image. The oxygen content of the core-shell hard phase intermediate powder is 0.15 wt%, the purity of the protective atmosphere is 99.95%, and the oxygen content is 50 ppm.

[0120] Step C: Preparation of the molding adhesive

[0121] (C1) Raw material preparation: Paraffin wax and stearic acid are provided. The melting point of paraffin wax is 55℃, and the purity of stearic acid is 98%.

[0122] (C2) Ratio: The mass ratio of paraffin to stearic acid is 12.5:1;

[0123] (C3) Mixing preparation: Paraffin wax and stearic acid are mixed at 90°C for 1.75 h to obtain a molding binder.

[0124] Step D: Preparation of radially gradient spherical preforms

[0125] (D1) Preparation of outer layer mixed powder: Based on a total mass of 100 parts by mass of the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 91.4 parts by mass of tungsten carbide, 8 parts by mass of multi-metal binder phase pre-alloyed powder, 0.4 parts by mass of vanadium carbide, and 0.2 parts by mass of graphite. The mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the outer layer mixed powder. All sources include vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form. The core-shell hard phase intermediate powder accounts for 65 wt% of the total tungsten carbide in the outer layer mixed powder, and the remainder is unmodified tungsten carbide powder. Mechanical mixing is used, and the mixing time is 6 hours.

[0126] (D2) Preparation of core-shell mixed powder: Based on a total mass of 100 parts by mass of core-shell mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core-shell mixed powder contains 83 parts by mass of tungsten carbide, 16 parts by mass of multi-metal binder phase pre-alloyed powder, 0.5 parts by mass of vanadium carbide, and 0.5 parts by mass of graphite to obtain core-shell mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the core-shell mixed powder, including vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form, and mechanical mixing is used, with a mixing time of 6 hours;

[0127] (D3) Granulation: Add forming binder to the outer layer mixed powder and the core mixed powder respectively, the amount of which is 2.25 wt% of the mass of each mixed powder. Heat and stir at 90℃ for 0.5 h to 3 h, then mix for 1.75 h to obtain the outer layer granulated powder and the core granulated powder respectively. After mixing, cool to room temperature and sieve to make the particle size of the obtained particles 0.10 mm to 2.00 mm.

[0128] (D4) Radial assembly forming: The core granulated powder and the outer granulated powder are filled into a spherical mold in sections. First, the core granulated powder is filled in the center of the mold, and then the outer granulated powder is filled in the outer layer. By controlling the section filling amount of the outer granulated powder and the core granulated powder, the outer layer thickness is 0.20 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. The blank is then uniaxially pressed with a pressure of 350 MPa and held for 30 s to obtain the radial gradient spherical blank.

[0129] (D5) Relative density control: The relative density of the radial gradient spherical blank is 60%. The relative density is the ratio of the measured density of the radial gradient spherical blank to the theoretical density calculated according to the formula of the outer layer mixed powder and the core mixed powder. The theoretical density is calculated according to the volume weighted average density of the outer layer region and the core region. The volume of the outer layer region is calculated according to the outer layer thickness. The volume of the core region is the total volume of the spherical blank minus the volume of the outer layer region. The measured density is determined by Archimedes' water displacement method, with anhydrous ethanol as the impregnation medium.

[0130] Step E: Degreasing

[0131] Under a vacuum of 100 Pa, the radial gradient spherical preform was heated from room temperature to 250°C at a heating rate of 5°C / min and held at that temperature for 1 hour. Then, it was heated to 400°C at a heating rate of 5°C / min and held at that temperature for 1.75 hours to remove the forming binder, so that the removal rate of the forming binder reached 95%. The removal rate was calculated according to the following formula: Removal rate = (M1-M2) / M0×100%; where M1 is the mass of the spherical preform before degreasing, M2 is the mass of the spherical preform after degreasing, and M0 is the theoretical mass of forming binder added to the spherical preform before degreasing, and M0 is calculated according to the amount of forming binder added in step C3.

[0132] Step F: Sintering

[0133] Under vacuum conditions of 25 Pa, the degreased spherical blank was heated from room temperature to 1100℃ at a heating rate of 10℃ / min and held for 1 h, and then heated to 1425℃ at a heating rate of 6℃ / min and held for 1.75 h for sintering; the relative density of the sintered spherical blank was 95%.

[0134] Step G: Hot Isostatic Pressing Densification Treatment

[0135] The sintered spherical blanks were subjected to hot isostatic pressing (HIP) densification under an argon atmosphere. The temperature was first raised to 1375℃ under normal pressure, then the pressure was increased to 100MPa and held at this temperature and pressure for 1.75h. Subsequently, the temperature was cooled to 700℃ at a cooling rate of 5℃ / min and held for 2h. Then, the blanks were furnace cooled to room temperature to obtain multi-component hard alloy wear-resistant balls. Since the relative density of the sintered spherical blanks is 95% and not less than 92%, the sintered spherical blanks do not need to be encased and can be directly subjected to HIP densification.

[0136] Final product performance

[0137] The obtained multi-component cemented carbide wear-resistant ball, after grinding, has a diameter of 80 mm and an absolute diameter deviation of 0.3 mm. The multi-component cemented carbide wear-resistant ball has an outer layer region and a core region along the radial direction. The outer layer region extends radially inward from the outer surface of the multi-component cemented carbide wear-resistant ball, and its thickness is 0.20 times the radius R of the multi-component cemented carbide wear-resistant ball. The core region is the remaining area excluding the outer layer region.

[0138] Based on the mass of the outer layer region, the mass fraction of the multi-metal binder phase is 8 wt%; based on the mass of the core region, the mass fraction of the multi-metal binder phase is 16 wt%. The average grain size of tungsten carbide in the outer layer region is 0.40 μm, and the average grain size of tungsten carbide in the core region is 1.15 μm. The average grain size was measured by the line section method in the microscopic image after polishing the cross-section of the multi-metal cemented carbide wear-resistant ball.

[0139] The multi-metal binder phase contains nano-precipitates with an equivalent diameter of 40 nm, which is the equivalent circle diameter measured in the transmission electron microscope image. The nano-precipitates are chromium-rich and molybdenum-rich phases. The nano-precipitates are characterized by transmission electron microscopy combined with energy dispersive spectroscopy. The atomic fraction of the enriched elements in the nano-precipitates is 8 at higher than that of the corresponding elements in the multi-metal binder phase.

[0140] The density of the multi-component cemented carbide wear-resistant ball is 14.65 g / cm³. 3 The Vickers hardness is HV1400, which was measured under a load of 9.8 N and a holding time of 12 s. The compressive strength is 5000 MPa, which was determined according to ISO4506:2018 standard.

[0141] Example 1 Features and Application Scenarios: This example uses moderate parameter configurations: tungsten carbide content is 86.5 wt%, multi-metal binder phase content is 12.5 wt%, outer layer binder phase content is 8 wt%, and core region binder phase content is 16 wt%, forming a moderate radial gradient structure. The average grain size of tungsten carbide in the outer layer is 0.40 μm, in the core region it is 1.15 μm, the sphere diameter is 80 mm, and the density is 14.65 g / cm³. 3 It has a Vickers hardness of HV1400 and a compressive strength of 5000MPa. This embodiment achieves a good balance between hardness, wear resistance, and toughness, with stable and reliable process parameters. It is suitable for grinding medium-sized ores, cement raw material grinding, ceramic raw material ball milling, and other grinding conditions requiring balanced comprehensive performance. It can be used as a grinding media in ball mills or semi-autogenous mills, with stable service life and uniform wear. Example

[0142] This embodiment provides a method for preparing a multi-component cemented carbide wear-resistant ball, including the following steps:

[0143] Step A: Preparation of pre-alloyed powder of multi-metal binder phase

[0144] (A1) Raw material preparation: Five metals, namely cobalt, nickel, iron, chromium and molybdenum, were selected as metal raw material powders with a particle size of 80 μm. In the multi-metal binder phase pre-alloyed powder, the atomic percentages of cobalt, nickel, iron and chromium were 12 at%, nickel, iron and chromium were 30 at%, chromium and molybdenum were 10 at%, and the sum of the atomic percentages of all metal elements was 100 at%.

[0145] (A2) Melting: Under an argon atmosphere with an argon purity of 99.95%, the metal raw material powder obtained in step A1 is heated to 1550℃ and held for 20 minutes to obtain a homogeneous alloy melt; a vacuum induction melting furnace is used for melting, the crucible material is a graphite crucible, the heating rate is 30℃ / min, the single feed amount is 2000g, and the melting temperature is determined according to the liquidus temperature of the alloy system, and heated to 70℃ above the liquidus temperature;

[0146] (A3) Atomization powder preparation: Inert gas atomization is adopted, with nitrogen as the atomizing gas, the atomization pressure is 3.5MPa, the atomizing gas flow rate is 400L / min, the nozzle diameter is 4mm, and the alloy melt temperature is controlled 90℃ above its liquidus temperature. The alloy melt is atomized to obtain multi-metal binder phase pre-alloyed powder.

[0147] (A4) Sieving and classifying: The multi-metal binder phase pre-alloyed powder obtained in step A3 is sieved to obtain multi-metal binder phase pre-alloyed powder with a particle size of 10μm to 75μm, wherein the volume distribution D10 is 12μm and D90 is 68μm.

[0148] (A5) Oxygen content control: By controlling the vacuum degree, protective atmosphere purity and atomization parameters in steps A2 and A3, the oxygen content of the obtained multi-metal binder phase pre-alloyed powder is 0.15wt%, wherein the oxygen content is measured by inert gas melting-infrared absorption method.

[0149] Step B: Preparation of core-shell hard phase intermediate powder

[0150] (B1) Raw material preparation: Tungsten carbide, vanadium carbide, and graphite are provided;

[0151] (B2) Proportion: Based on 100 parts by mass of tungsten carbide, 0.6 parts by mass of vanadium carbide and 0.15 parts by mass of graphite;

[0152] (B3) Coating and mixing: Under a nitrogen atmosphere, the raw materials described in step B1 are ball-milled and mixed according to the proportions described in step B2. The ball milling speed is 200 r / min, the ball milling time is 8 h, the ball-to-powder ratio is 7:1, the ball-to-powder ratio is the mass ratio of the ball milling media to the powder, and the filling coefficient of the ball milling jar is 55%. The filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball milling jar to the inner volume of the ball milling jar. This allows vanadium carbide and graphite to adhere to the surface of tungsten carbide particles, resulting in coated and mixed powder. The ball milling media are zirconia balls with a diameter of 8 mm, and a planetary ball mill is used with a revolution speed of 200 r / min.

[0153] (B4) Heat treatment to form a shell: Under an argon atmosphere, the coated mixed powder obtained in step B3 is heated to 1000℃ at a heating rate of 12℃ / min and held for 2h. Then it is furnace cooled to room temperature at a cooling rate of 7℃ / min to obtain a core-shell hard phase intermediate powder.

[0154] (B5) Shell Parameter Control: By controlling the ball milling time and ball-to-material ratio in step B3 and the heat treatment temperature and time in step B4, the shell thickness of the obtained core-shell hard phase intermediate powder is 20 nm and the shell coverage is 92%. The shell thickness and shell coverage are confirmed by transmission electron microscopy. Ten fields of view are randomly selected and 200 particles are counted. The shell coverage is the percentage of particles with continuous shells to the total number of counted particles. A continuous shell refers to a shell that is continuously covered along the surface of the tungsten carbide particle without visible interruption in the microscopic image. The oxygen content of the core-shell hard phase intermediate powder is 0.12 wt%, the purity of the protective atmosphere is 99.98%, and the oxygen content is 30 ppm.

[0155] Step C: Preparation of the molding adhesive

[0156] (C1) Raw material preparation: Paraffin wax and stearic acid are provided. The melting point of paraffin wax is 54℃, and the purity of stearic acid is 97%.

[0157] (C2) Ratio: The mass ratio of paraffin to stearic acid is 8:1;

[0158] (C3) Mixing preparation: Paraffin wax and stearic acid are mixed at 75°C for 1.2 h to obtain a molding binder.

[0159] Step D: Preparation of radially gradient spherical preforms

[0160] (D1) Preparation of outer layer mixed powder: With a total mass of 100 parts by mass for the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 92.8 parts by mass of tungsten carbide, 6.5 parts by mass of multi-metal binder phase pre-alloyed powder, 0.5 parts by mass of vanadium carbide, and 0.2 parts by mass of graphite. The mass parts of vanadium carbide and graphite represent the total mass parts of all sources of vanadium carbide and graphite in the outer layer mixed powder. The source contains vanadium carbide and graphite in the shell of the core-shell hard phase intermediate powder, as well as vanadium carbide and graphite added in powder form; the core-shell hard phase intermediate powder in the outer mixed powder accounts for 70 wt% of the total tungsten carbide, and the rest is unmodified tungsten carbide powder. The ball milling method is adopted, the ball milling speed is 180 r / min, the ball milling time is 5 h, the ball-to-material ratio is 5:1, the filling coefficient of the ball milling jar is 45%, the ball milling is dry ball milling, and the ball milling media is zirconium dioxide balls.

[0161] (D2) Preparation of core-mixed powder: Based on a total mass of 100 parts by mass of core-mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core-mixed powder contains 85 parts by mass of tungsten carbide, 13.5 parts by mass of multi-metal binder phase pre-alloyed powder, 0.8 parts by mass of vanadium carbide, and 0.7 parts by mass of graphite to obtain core-mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the core-mixed powder, including vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form. The ball milling method is adopted, the ball milling speed is 180 r / min, the ball milling time is 5 h, the ball-to-material ratio is 5:1, the filling coefficient of the ball milling jar is 45%, the ball milling is dry ball milling, and the ball milling media is zirconium dioxide balls;

[0162] (D3) Granulation: Add forming binder to the outer layer mixed powder and the core mixed powder respectively, the amount of which is 1.5wt% of the mass of each mixed powder, and mix by heating and stirring at 75℃ for 1.2h to obtain the outer layer granulated powder and the core granulated powder respectively; after mixing, cool to room temperature and sieve to make the particle size of the obtained particles 0.15mm to 1.50mm;

[0163] (D4) Radial assembly forming: The core granulated powder and the outer granulated powder are filled into a spherical mold in sections. First, the core granulated powder is filled in the center of the mold, and then the outer granulated powder is filled in the outer layer. By controlling the section filling amount of the outer granulated powder and the core granulated powder, the outer layer thickness is 0.25 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. The blank is then uniaxially pressed with a pressure of 450 MPa and held for 25 s to obtain the radial gradient spherical blank.

[0164] (D5) Relative density control: The relative density of the radial gradient spherical blank is 65%. The relative density is the ratio of the measured density of the radial gradient spherical blank to the theoretical density calculated according to the formula of the outer layer mixed powder and the core mixed powder. The theoretical density is calculated according to the volume weighted average density of the outer layer region and the core region. The volume of the outer layer region is calculated according to the outer layer thickness. The volume of the core region is the total volume of the spherical blank minus the volume of the outer layer region. The measured density is determined by Archimedes' water displacement method with kerosene as the impregnation medium.

[0165] Step E: Degreasing

[0166] Under an argon atmosphere with a purity of 99.95%, the radial gradient spherical preform was heated from room temperature to 220°C at a rate of 3°C / min and held for 0.8 h. Then, it was heated to 300°C at a rate of 3°C / min and held for 0.7 h to remove the forming binder, achieving a removal rate of 93%. The removal rate was calculated using the following formula: Removal rate = (M1 - M2) / M0 × 100%; where M1 is the mass of the spherical preform before degreasing, M2 is the mass of the spherical preform after degreasing, and M0 is the theoretical mass of forming binder added to the spherical preform before degreasing, calculated based on the amount of forming binder added in step C3.

[0167] Step F: Sintering

[0168] Under vacuum conditions of 15 Pa, the degreased spherical blank was heated from room temperature to 1050℃ at a heating rate of 8℃ / min and held for 0.8h, and then heated to 1400℃ at a heating rate of 5℃ / min and held for 1.2h for sintering; the relative density of the sintered spherical blank was 96%.

[0169] Step G: Hot Isostatic Pressing Densification Treatment

[0170] The sintered spherical blanks were subjected to hot isostatic pressing (HIP) densification under an argon atmosphere. The temperature was first raised to 1340℃ at atmospheric pressure, then the pressure was increased to 80MPa and held at this temperature and pressure for 1.2h. Subsequently, the temperature was cooled to 650℃ at a cooling rate of 4℃ / min and held for 1.5h. Then, the blanks were furnace cooled to room temperature to obtain multi-component hard alloy wear-resistant balls. Since the relative density of the sintered spherical blanks is 96% and not less than 92%, the sintered spherical blanks do not need to be encased and can be directly subjected to HIP densification.

[0171] Final product performance

[0172] The obtained multi-component cemented carbide wear-resistant ball, after grinding, has a diameter of 50 mm and an absolute diameter deviation of 0.2 mm. The multi-component cemented carbide wear-resistant ball has an outer layer region and a core region along the radial direction. The outer layer region extends radially inward from the outer surface of the multi-component cemented carbide wear-resistant ball, and its thickness is 0.25 times the radius R of the multi-component cemented carbide wear-resistant ball. The core region is the remaining area excluding the outer layer region.

[0173] Based on the mass of the outer layer region, the mass fraction of the multi-metal binder phase is 6.5 wt%; based on the mass of the core region, the mass fraction of the multi-metal binder phase is 13.5 wt%. The average grain size of tungsten carbide in the outer layer region is 0.30 μm, and the average grain size of tungsten carbide in the core region is 0.95 μm. The average grain size was measured by the line section method in the microscopic image after polishing the cross-section of the multi-metal cemented carbide wear-resistant ball.

[0174] The multi-metal binder phase contains nano-precipitates with an equivalent diameter of 35 nm, which is the equivalent circle diameter measured in the transmission electron microscope image. The nano-precipitates are chromium-rich phases and are characterized by transmission electron microscopy combined with energy dispersive spectroscopy. The atomic fraction of the enriched elements in the nano-precipitates is 6 at higher than that of the corresponding elements in the multi-metal binder phase.

[0175] The density of the multi-component cemented carbide wear-resistant ball is 14.9 g / cm³. 3 The Vickers hardness is HV1500, which was measured under a load of 9.8 N and a holding time of 12 s. The compressive strength is 5500 MPa, which was determined according to ISO4506:2018 standard.

[0176] Example 2 Features and Application Scenarios: This example employs an optimized configuration for high hardness and high wear resistance, with a high tungsten carbide content. The outer layer mixed powder contains 92.8 parts by weight of tungsten carbide, while the core mixed powder contains 85 parts by weight. The content of the multi-metal binder phase is relatively low, with the outer layer containing 6.5 wt% and the core containing 13.5 wt%. The average grain size of tungsten carbide in the outer layer is 0.30 μm, and in the core it is 0.95 μm, forming a fine-grained, high-hardness outer layer structure. The sphere diameter is 50 mm, and the density is 14.9 g / cm³. 3 With a Vickers hardness of up to HV1500 and a compressive strength of 5500MPa, this embodiment exhibits excellent wear resistance and surface hardness, making it suitable for demanding applications requiring high wear resistance, such as grinding high-hardness ores, fine grinding of metal ores, and surface strengthening grinding of high-chromium cast iron parts. It can be used as a grinding media in ball mills or semi-autogenous mills, and is particularly suitable for processing hard materials such as quartz sand, iron ore, and copper ore. Example

[0177] This embodiment provides a method for preparing a multi-component cemented carbide wear-resistant ball, including the following steps:

[0178] Step A: Preparation of pre-alloyed powder of multi-metal binder phase

[0179] (A1) Raw material preparation: Five metals, namely cobalt, nickel, iron, chromium and molybdenum, were selected as metal raw material powders with a particle size of 120 μm. In the multi-metal binder phase pre-alloyed powder, the atomic percentages of cobalt, nickel, iron and chromium were 35 at%, nickel and iron were 20 at%, chromium and molybdenum were 13 at%, and the total atomic percentage of all metal elements was 100 at%.

[0180] (A2) Melting: Under a vacuum of 40 Pa, the metal raw material powder obtained in step A1 is heated to 1650℃ and held for 50 min to obtain a uniform alloy melt; a vacuum arc melting furnace is used for melting, the crucible material is a water-cooled copper crucible, the heating rate is 40℃ / min, the single feed amount is 3000g, and the melting temperature is determined according to the liquidus temperature of the alloy system, and heated to 150℃ above the liquidus temperature;

[0181] (A3) Atomization powder preparation: Inert gas atomization is adopted, with argon as the atomizing gas, the atomization pressure is 6.5MPa, the atomizing gas flow rate is 700L / min, the nozzle diameter is 6mm, and the alloy melt temperature is controlled 160℃ above its liquidus temperature. The alloy melt is atomized to obtain multi-metal binder phase pre-alloyed powder.

[0182] (A4) Sieving and classifying: The multi-metal binder phase pre-alloyed powder obtained in step A3 is sieved to obtain multi-metal binder phase pre-alloyed powder with a particle size of 10μm to 75μm, wherein the volume distribution D10 is 18μm and D90 is 72μm.

[0183] (A5) Oxygen content control: By controlling the vacuum degree, protective atmosphere purity and atomization parameters in steps A2 and A3, the oxygen content of the obtained multi-metal binder phase pre-alloyed powder is 0.35wt%, wherein the oxygen content is measured by inert gas melting-infrared absorption method.

[0184] Step B: Preparation of core-shell hard phase intermediate powder

[0185] (B1) Raw material preparation: Tungsten carbide, vanadium carbide, and graphite are provided;

[0186] (B2) Proportion: Based on 100 parts by mass of tungsten carbide, 1.5 parts by mass of vanadium carbide and 0.40 parts by mass of graphite;

[0187] (B3) Coating and mixing: Under an argon atmosphere, the raw materials described in step B1 are ball-milled and mixed according to the proportions described in step B2. The ball milling speed is 130 r / min, the ball milling time is 4 h, the ball-to-powder ratio is 4:1, the ball-to-powder ratio is the mass ratio of the ball milling media to the powder, and the filling coefficient of the ball milling jar is 40%. The filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball milling jar to the inner volume of the ball milling jar. This allows vanadium carbide and graphite to adhere to the surface of tungsten carbide particles, resulting in coated and mixed powder. The ball milling media are zirconia balls with a diameter of 15 mm, and a drum ball mill is used with a speed of 130 r / min.

[0188] (B4) Heat treatment to form a shell: Under a protective atmosphere, the protective atmosphere is nitrogen atmosphere. The coated mixed powder obtained in step B3 is heated to 900℃ at a heating rate of 8℃ / min and held for 1.2h. Then it is furnace cooled to room temperature at a cooling rate of 6℃ / min to obtain core-shell hard phase intermediate powder.

[0189] (B5) Shell Parameter Control: By controlling the ball milling time and ball-to-material ratio in step B3 and the heat treatment temperature and time in step B4, the shell thickness of the obtained core-shell hard phase intermediate powder is 10 nm and the shell coverage is 85%. The shell thickness is confirmed by transmission electron microscopy, and the shell coverage is confirmed by scanning electron microscopy. Six fields of view are randomly selected and 120 particles are counted. The shell coverage is the percentage of particles with continuous shells to the total number of counted particles. A continuous shell refers to a shell that is continuously covered along the surface of the tungsten carbide particle without visible interruption in the microscopic image. The oxygen content of the core-shell hard phase intermediate powder is 0.20 wt%, the purity of the protective atmosphere is 99.92%, and the oxygen content is 80 ppm.

[0190] Step C: Preparation of the molding adhesive

[0191] (C1) Raw material preparation: Paraffin wax and stearic acid are provided. The melting point of paraffin wax is 56℃, and the purity of stearic acid is 96%.

[0192] (C2) Ratio: The mass ratio of paraffin to stearic acid is 16:1;

[0193] (C3) Mixing preparation: Paraffin wax and stearic acid are mixed at 105°C for 2.3 h to obtain a molding binder.

[0194] Step D: Preparation of radially gradient spherical preforms

[0195] (D1) Preparation of outer layer mixed powder: Based on a total mass of 100 parts by mass of the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 89.6 parts by mass of tungsten carbide, 9.5 parts by mass of multi-metal binder phase pre-alloyed powder, 0.7 parts by mass of vanadium carbide, and 0.2 parts by mass of graphite. The mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the outer layer mixed powder. All sources include vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form. The core-shell hard phase intermediate powder accounts for 50 wt% of the total tungsten carbide in the outer layer mixed powder, and the remainder is unmodified tungsten carbide powder. Mechanical mixing is used, and the mixing time is 8 hours.

[0196] (D2) Preparation of core-mixed powder: Based on a total mass of 100 parts by mass of core-mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core-mixed powder contains 80 parts by mass of tungsten carbide, 18.5 parts by mass of multi-metal binder phase pre-alloyed powder, 0.8 parts by mass of vanadium carbide, and 0.7 parts by mass of graphite to obtain core-mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the core-mixed powder, including vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form, and mechanical mixing is used, with a mixing time of 8 hours;

[0197] (D3) Granulation: Add forming binder to the outer layer mixed powder and the core mixed powder respectively, the amount of which is 3.0 wt% of the mass of each mixed powder, and knead and mix at 105℃ for 2.3 h to obtain the outer layer granulated powder and the core granulated powder respectively; after mixing, cool to room temperature and sieve to make the particle size of the obtained particles 0.20 mm to 1.80 mm;

[0198] (D4) Radial assembly forming: The core granulated powder and the outer granulated powder are filled into a spherical mold in sections. First, the core granulated powder is filled in the center of the mold, and then the outer granulated powder is filled in the outer layer. By controlling the section filling amount of the outer layer granulated powder and the core granulated powder, the outer layer thickness is 0.15 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. Cold isostatic pressing is performed at a pressure of 250MPa and the pressure is held for 40s to obtain the radial gradient spherical blank.

[0199] (D5) Relative density control: The relative density of the radial gradient spherical blank is 55%. The relative density is the ratio of the measured density of the radial gradient spherical blank to the theoretical density calculated according to the formula of the outer layer mixed powder and the core mixed powder. The theoretical density is calculated according to the volume weighted average density of the outer layer region and the core region. The volume of the outer layer region is calculated according to the outer layer thickness. The volume of the core region is the total volume of the spherical blank minus the volume of the outer layer region. The measured density is determined by Archimedes' displacement method, with anhydrous ethanol as the impregnation medium.

[0200] Step E: Degreasing

[0201] Under a protective atmosphere, namely nitrogen atmosphere with a purity of 99.93%, the radial gradient spherical preform was heated from room temperature to 280℃ at a heating rate of 8℃ / min and held at that temperature for 1.5h. Then, it was heated to 500℃ at a heating rate of 8℃ / min and held at that temperature for 2.5h to remove the forming binder, so that the removal rate of the forming binder reached 97%. The removal rate was calculated according to the following formula: Removal rate = (M1-M2) / M0×100%; where M1 is the mass of the spherical preform before degreasing, M2 is the mass of the spherical preform after degreasing, and M0 is the theoretical mass of forming binder added to the spherical preform before degreasing, and M0 is calculated according to the amount of forming binder added in step C3.

[0202] Step F: Sintering

[0203] Under vacuum conditions of 35 Pa, the degreased spherical blank was heated from room temperature to 1150 °C at a heating rate of 12 °C / min and held for 1.5 h, and then heated to 1450 °C at a heating rate of 8 °C / min and held for 2.3 h for sintering; the relative density of the sintered spherical blank was 94%.

[0204] Step G: Hot Isostatic Pressing Densification Treatment

[0205] The sintered spherical blanks were subjected to hot isostatic pressing (HIP) densification under an argon atmosphere. The temperature was first raised to 1420℃ under normal pressure, and then the pressure was increased to 130MPa. The temperature and pressure were maintained at this level for 2.3 hours. Subsequently, the blanks were cooled to 800℃ at a cooling rate of 8℃ / min and held for 3 hours. Then, the blanks were furnace cooled to room temperature to obtain multi-component hard alloy wear-resistant balls. Since the relative density of the sintered spherical blanks is 94% and not less than 92%, the sintered spherical blanks do not need to be encased and can be directly subjected to HIP densification.

[0206] Final product performance

[0207] The obtained multi-component cemented carbide wear-resistant ball, after polishing, has a diameter of 120 mm and an absolute diameter deviation of 0.4 mm. The multi-component cemented carbide wear-resistant ball has an outer layer region and a core region along the radial direction. The outer layer region extends radially inward from the outer surface of the multi-component cemented carbide wear-resistant ball, and its thickness is 0.15 times the radius R of the multi-component cemented carbide wear-resistant ball. The core region is the remaining area excluding the outer layer region.

[0208] Based on the mass of the outer layer region, the mass fraction of the multi-metal binder phase is 9.5 wt%; based on the mass of the core region, the mass fraction of the multi-metal binder phase is 18.5 wt%. The average grain size of tungsten carbide in the outer layer region is 0.50 μm, and the average grain size of tungsten carbide in the core region is 1.35 μm. The average grain size was measured by the line section method in the microscopic image after polishing the cross-section of the multi-metal cemented carbide wear-resistant ball.

[0209] The multi-metal binder phase contains nano-precipitates with an equivalent diameter of 50 nm, which is the equivalent circle diameter measured in the transmission electron microscope image. The nano-precipitates are molybdenum-rich phases. The nano-precipitates are characterized by transmission electron microscopy combined with energy dispersive spectroscopy. The atomic fraction of enriched elements in the nano-precipitates is 7 at higher than that of the corresponding elements in the multi-metal binder phase.

[0210] The density of the multi-component cemented carbide wear-resistant ball is 14.3 g / cm³. 3 The Vickers hardness is HV1300, which was measured under a load of 9.8 N and a holding time of 13 s. The compressive strength is 4500 MPa, which was determined according to ISO4506:2018 standard.

[0211] Example 3 Features and Application Scenarios: This example employs a high-toughness optimized configuration with a high content of multi-metal binder phase. The binder phase in the outer layer mixed powder is 9.5 parts by weight, and the binder phase in the core mixed powder is 18.5 parts by weight. The binder phase content in the outer layer is 9.5 wt%, and the binder phase content in the core is 18.5 wt%. The tungsten carbide content is relatively low. The average grain size of tungsten carbide in the outer layer is 0.50 μm, and in the core is 1.35 μm, forming a coarse-grained, high-toughness structure. The sphere diameter is 120 mm, and the density is 14.3 g / cm³. 3 It has a Vickers hardness of HV1300, a compressive strength of 4500MPa, and a cobalt content of up to 35at in the multi-metal binder phase. This embodiment exhibits excellent impact toughness and fracture toughness, making it suitable for processing lumpy ores, slurries containing large hard inclusions, and grinding conditions requiring strong impact in large-diameter ball mills, autogenous mills, or semi-autogenous mills. It can be used as a grinding media, and is particularly suitable for processing materials such as iron ore, copper ore, and gold ore that require strong impact loads. It has a long service life and a low breakage rate. Example

[0212] This embodiment provides a method for preparing a multi-component cemented carbide wear-resistant ball, including the following steps:

[0213] Step A: Preparation of pre-alloyed powder of multi-metal binder phase

[0214] (A1) Raw material preparation: Four metals, cobalt, nickel, iron, and chromium, were selected as metal raw material powders with a particle size of 15 μm. In the multi-metal binder phase pre-alloyed powder, the atomic percentage of cobalt was 30 at%, the atomic percentage of nickel was 35 at%, the atomic percentage of iron was 25 at%, the atomic percentage of chromium was 10 at%, and the atomic percentage of molybdenum was 0 at%. The sum of the atomic percentages of all metal elements was 100 at%.

[0215] (A2) Melting: Under a vacuum of 5 Pa, the metal raw material powder obtained in step A1 is heated to 1520℃ and held for 15 min to obtain a uniform alloy melt; a vacuum induction melting furnace is used for melting, the crucible material is a graphite crucible, the heating rate is 10℃ / min, the single feed amount is 800g, and the melting temperature is determined according to the liquidus temperature of the alloy system, and heated to 50℃ above the liquidus temperature;

[0216] (A3) Atomization powder preparation: Inert gas atomization is adopted, with argon as the atomizing gas, the atomization pressure is 7.5MPa, the atomizing gas flow rate is 850L / min, the nozzle diameter is 7mm, and the alloy melt temperature is controlled 180℃ above its liquidus temperature. The alloy melt is atomized to obtain multi-metal binder phase pre-alloyed powder.

[0217] (A4) Sieving and classifying: The multi-metal binder phase pre-alloyed powder obtained in step A3 is sieved to obtain multi-metal binder phase pre-alloyed powder with a particle size of 10μm to 75μm, wherein the volume distribution D10 is 11μm and D90 is 73μm.

[0218] (A5) Oxygen content control: By controlling the vacuum degree, protective atmosphere purity and atomization parameters in steps A2 and A3, the oxygen content of the obtained multi-metal binder phase pre-alloyed powder is 0.05wt%, wherein the oxygen content is measured by inert gas melting-infrared absorption method.

[0219] Step B: Preparation of core-shell hard phase intermediate powder

[0220] (B1) Raw material preparation: Tungsten carbide, vanadium carbide, and graphite are provided;

[0221] (B2) Proportion: Based on 100 parts by mass of tungsten carbide, 0.2 parts by mass of vanadium carbide and 0.08 parts by mass of graphite;

[0222] (B3) Coating and mixing: Under an argon atmosphere, the raw materials described in step B1 are ball-milled and mixed according to the proportions described in step B2. The ball milling speed is 280 r / min, the ball milling time is 1.5 h, the ball-to-powder ratio is 9:1, the ball-to-powder ratio is the mass ratio of the ball milling media to the powder, and the filling coefficient of the ball milling jar is 65%. The filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball milling jar to the inner volume of the ball milling jar. This allows vanadium carbide and graphite to adhere to the surface of tungsten carbide particles, resulting in coated and mixed powder. The ball milling media are zirconia balls with a diameter of 5 mm, and a planetary ball mill is used with a revolution speed of 280 r / min.

[0223] (B4) Heat treatment to form a shell: Under a vacuum of 10 Pa, the coated mixed powder obtained in step B3 is heated to 850 °C at a heating rate of 15 °C / min and held for 0.7 h. Then it is furnace cooled to room temperature at a cooling rate of 9 °C / min to obtain a core-shell hard phase intermediate powder.

[0224] (B5) Shell Parameter Control: By controlling the ball milling time and ball-to-material ratio in step B3 and the heat treatment temperature and time in step B4, the shell thickness of the obtained core-shell hard phase intermediate powder is 5 nm and the shell coverage is 95%. The shell thickness and shell coverage are confirmed by transmission electron microscopy. Twelve fields of view are randomly selected and 250 particles are counted. The shell coverage is the percentage of particles with continuous shells to the total number of counted particles. A continuous shell refers to a shell that is continuously covered along the surface of the tungsten carbide particle without visible interruption in the microscopic image. The oxygen content of the core-shell hard phase intermediate powder is 0.08 wt%, the purity of the protective atmosphere is 99.99%, and the oxygen content is 20 ppm.

[0225] Step C: Preparation of the molding adhesive

[0226] (C1) Raw material preparation: Paraffin wax and stearic acid are provided. The melting point of paraffin wax is 53℃, and the purity of stearic acid is 99%.

[0227] (C2) Ratio: The mass ratio of paraffin to stearic acid is 18:1;

[0228] (C3) Mixing preparation: Paraffin wax and stearic acid are mixed at 65°C for 0.7 h to obtain a molding binder.

[0229] Step D: Preparation of radially gradient spherical preforms

[0230] (D1) Preparation of outer layer mixed powder: With a total mass of 100 parts by mass for the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 93.5 parts by mass of tungsten carbide, 6.2 parts by mass of multi-metal binder pre-alloyed powder, 0.2 parts by mass of vanadium carbide, and 0.1 parts by mass of graphite. The mass parts of vanadium carbide and graphite are the total mass parts of all sources of vanadium carbide and graphite in the outer layer mixed powder. The source contains vanadium carbide and graphite in the shell of the core-shell hard phase intermediate powder, as well as vanadium carbide and graphite added in powder form; the core-shell hard phase intermediate powder in the outer mixed powder accounts for 85 wt% of the total tungsten carbide, and the rest is unmodified tungsten carbide powder. The ball milling method is adopted, the ball milling speed is 250 r / min, the ball milling time is 2 h, the ball-to-material ratio is 8:1, the filling coefficient of the ball milling jar is 60%, the ball milling is dry ball milling, and the ball milling media is zirconium dioxide balls.

[0231] (D2) Preparation of core-mixed powder: Based on a total mass of 100 parts by mass of core-mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core-mixed powder contains 87 parts by mass of tungsten carbide, 12.5 parts by mass of multi-metal binder phase pre-alloyed powder, 0.3 parts by mass of vanadium carbide, and 0.2 parts by mass of graphite to obtain core-mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the core-mixed powder, including vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form. The ball milling method is adopted, the ball milling speed is 250 r / min, the ball milling time is 2 h, the ball-to-material ratio is 8:1, the filling coefficient of the ball milling jar is 60%, the ball milling is dry ball milling, and the ball milling media is zirconium dioxide balls;

[0232] (D3) Granulation: A forming binder is added to the outer layer mixed powder and the core mixed powder respectively, with the amount added being 0.7wt% of the mass of each mixed powder. The mixture is heated and stirred at 65℃ for 0.7h to obtain the outer layer granulated powder and the core granulated powder respectively. After mixing, the mixture is cooled to room temperature and sieved to make the particle size of the obtained particles 0.12mm to 1.20mm.

[0233] (D4) Radial assembly forming: The core granulated powder and the outer granulated powder are filled into a spherical mold in sections. First, the core granulated powder is filled in the center of the mold, and then the outer granulated powder is filled in the outer layer. By controlling the section filling amount of the outer layer granulated powder and the core granulated powder, the outer layer thickness is 0.12 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. The blank is then uniaxially pressed with a pressure of 550 MPa and held for 45 s to obtain the radial gradient spherical blank.

[0234] (D5) Relative density control: The relative density of the radial gradient spherical blank is 67%. The relative density is the ratio of the measured density of the radial gradient spherical blank to the theoretical density calculated according to the formula of the outer layer mixed powder and the core mixed powder. The theoretical density is calculated according to the volume weighted average density of the outer layer region and the core region. The volume of the outer layer region is calculated according to the outer layer thickness. The volume of the core region is the total volume of the spherical blank minus the volume of the outer layer region. The measured density is determined by Archimedes' displacement method, with anhydrous ethanol as the impregnation medium.

[0235] Step E: Degreasing

[0236] Under vacuum conditions of 20 Pa, the radial gradient spherical preform was heated from room temperature to 210℃ at a heating rate of 2℃ / min and held at that temperature for 0.6 h. Then, it was heated to 250℃ at a heating rate of 2℃ / min and held at that temperature for 0.2 h to remove the forming binder, so that the removal rate of the forming binder reached 91%. The removal rate was calculated according to the following formula: Removal rate = (M1-M2) / M0×100%; where M1 is the mass of the spherical preform before degreasing, M2 is the mass of the spherical preform after degreasing, and M0 is the theoretical mass of forming binder added to the spherical preform before degreasing, and M0 is calculated according to the amount of forming binder added in step C3.

[0237] Step F: Sintering

[0238] Under vacuum conditions of 3 Pa, the degreased spherical blank was heated from room temperature to 1180℃ at a heating rate of 13℃ / min and held for 0.6 h, and then heated to 1480℃ at a heating rate of 9℃ / min and held for 0.7 h for sintering; the relative density of the sintered spherical blank was 97%.

[0239] Step G: Hot Isostatic Pressing Densification Treatment

[0240] The sintered spherical blanks were subjected to hot isostatic pressing (HIP) densification under an argon atmosphere. The temperature was first raised to 1430℃ under normal pressure, then the pressure was increased to 60MPa and held at this temperature and pressure for 0.7h. Subsequently, the temperature was cooled to 550℃ at a cooling rate of 2℃ / min and held for 1h. Then, the blanks were furnace cooled to room temperature to obtain multi-component hard alloy wear-resistant balls. Since the relative density of the sintered spherical blanks is 97% and not less than 92%, the sintered spherical blanks do not need to be encased and can be directly subjected to HIP densification.

[0241] Final product performance

[0242] The obtained multi-component cemented carbide wear-resistant ball, after grinding, has a diameter of 10 mm and an absolute diameter deviation of 0.1 mm. The multi-component cemented carbide wear-resistant ball has an outer layer region and a core region along the radial direction. The outer layer region extends radially inward from the outer surface of the multi-component cemented carbide wear-resistant ball, and its thickness is 0.12 times the radius R of the multi-component cemented carbide wear-resistant ball. The core region is the remaining area excluding the outer layer region.

[0243] Based on the mass of the outer layer region, the mass fraction of the multi-metal binder phase is 6.2 wt%; based on the mass of the core region, the mass fraction of the multi-metal binder phase is 12.5 wt%. The average grain size of tungsten carbide in the outer layer region is 0.25 μm, and the average grain size of tungsten carbide in the core region is 0.90 μm. The average grain size was measured by the line section method in the microscopic image after polishing the cross-section of the multi-metal cemented carbide wear-resistant ball.

[0244] The multi-metal binder phase contains nano-precipitates with an equivalent diameter of 25 nm, which is the equivalent circle diameter measured in the transmission electron microscope image. The nano-precipitates are chromium-rich phases and are characterized by transmission electron microscopy combined with energy dispersive spectroscopy. The atomic fraction of the enriched elements in the nano-precipitates is 5 at higher than that of the corresponding elements in the multi-metal binder phase.

[0245] The density of the multi-component cemented carbide wear-resistant ball is 15.1 g / cm³. 3 The Vickers hardness is HV1550, which was measured under a load of 9.8 N and a holding time of 11 s. The compressive strength is 5700 MPa, which was determined according to ISO4506:2018 standard.

[0246] Example 4 Features and Application Scenarios: This example uses a parameter range expansion verification configuration, selecting four metallic elements to prepare a multi-metal binder phase pre-alloyed powder with a particle size of 15 μm, a vacuum degree of 5 Pa, an atomization pressure of 7.5 MPa, and a core-shell hard phase intermediate powder composition of 0.2 parts by mass of vanadium carbide and 0.08 parts by mass of graphite. The ball milling speed is 280 r / min, the ball milling time is 1.5 h, the ball-to-material ratio is 9:1, the filling coefficient is 65%, and the heat treatment temperature is 850℃. The outer layer mixed powder contains 93.5 parts by weight of tungsten carbide and 6.2 parts by weight of binder phase; the core mixed powder contains 87 parts by weight of tungsten carbide and 12.5 parts by weight of binder phase; the amount of forming binder added is 0.7 wt%; the paraffin-stearic acid mass ratio is 18:1; the pressing pressure is 550 MPa; the relative density is 67%; the sintering temperature is 1480℃; the hot isostatic pressing temperature is 1430℃; the outer layer thickness is 0.12R; the sphere diameter is 10 mm; and the density is 15.1 g / cm³. 3The Vickers hardness is HV1550, and the compressive strength is 5700MPa. The process parameters in this embodiment cover a wide range, verifying both the feasibility of preparing small-diameter spheres and the applicability of process conditions such as high pressing pressure and high sintering temperature. It is suitable for applications requiring small-diameter, high-performance grinding media, such as precision small ball mills, laboratory grinding equipment, micron powder preparation, and fine ceramic powder grinding. It can be used as a grinding media and possesses ultra-high hardness and excellent wear resistance.

[0247] Comparative Example 1: It is basically the same as Example 1, except that the multi-metal binder phase pre-alloyed powder is made by alloying only three metal elements: cobalt, nickel and iron. The atomic percentage of cobalt is 33 at%, the atomic percentage of nickel is 33 at%, and the atomic percentage of iron is 34 at%. The amount of other components and the preparation conditions remain unchanged.

[0248] Comparative Example 2: It is basically the same as Example 1, except that the amount of multi-metal binder pre-alloyed powder in the outer layer mixed powder is 5 parts by mass, and the amount of multi-metal binder pre-alloyed powder in the core mixed powder is 21 parts by mass. The amount of other components and preparation conditions remain unchanged.

[0249] Comparative Example 3: It is basically the same as Example 1, except that the amount of vanadium carbide in the outer layer mixed powder is 1.5 parts by mass, while the amount of other components and preparation conditions remain unchanged.

[0250] Comparative Example 4: It is basically the same as Example 1, except that the amount of graphite in the core mixed powder is 0.8 parts by mass, while the amount of other components and preparation conditions remain unchanged.

[0251] Comparative Example 5: It is basically the same as Example 1, except that the tungsten carbide in the outer mixed powder is all unmodified tungsten carbide powder, and no core-shell hard phase intermediate powder is used. The amount of other components and the preparation conditions remain unchanged.

[0252] Comparative Example 6: It is basically the same as Example 1, except that the partitioned filling amount of the outer layer granulated powder and the core granulated powder makes the outer layer thickness 0.05 times the radius R of the radial gradient spherical preform, while the amount of other components and preparation conditions remain unchanged.

[0253] Comparative Example 7: It is basically the same as Example 1, except that the sintering temperature is 1320℃, while the amount of other components and preparation conditions remain unchanged.

[0254] Comparative Example 8: It is basically the same as Example 1, except that the pressure of hot isostatic pressing densification is 35 MPa, while the amount of other components and preparation conditions remain unchanged.

[0255] Performance testing:

[0256] Experiment Name: Vickers Hardness Test

[0257] Test Object: Finished multi-component cemented carbide wear-resistant balls and their outer and inner core regions. Test Objective: To evaluate the deformation resistance and basic wear resistance properties of multi-component cemented carbide wear-resistant balls, and to verify the influence of radial gradient structural design on hardness distribution. Test Principle: The standard Vickers indentation method is used. The Vickers hardness value is calculated by measuring the diagonal length formed by the diamond indenter indenting the material surface under a specified load. Experimental Method: The multi-component cemented carbide wear-resistant ball is cut along its diameter and inlaid, then polished to a mirror finish. Using a micro Vickers hardness tester, under a load of 9.8 N and a holding time of 12 s, indentation tests are performed at 0.5 mm and 1.0 mm from the surface in the outer layer region, and at the center of the core region. Five points are tested at each location, and the average value is taken. Key Parameters: Load 9.8 N, holding time 12 s, test environment temperature 23±2℃, relative humidity ≤60%RH. Data Processing: The average hardness and standard deviation of each region are calculated, and a radial hardness distribution curve is plotted.

[0258] Experiment Title: Compressive Strength Test

[0259] Test Object: Finished multi-component cemented carbide wear-resistant balls. Test Objective: To evaluate the fracture resistance reliability of multi-component cemented carbide wear-resistant balls under high impact load conditions in a ball mill, and to verify the contribution of the radial gradient structure and multi-component metal bonding to the overall toughness. Test Principle: By applying a uniaxial compressive load on a material testing machine, the maximum load value at the moment of ball breakage is measured, and the compressive strength is calculated. Experimental Method: The multi-component cemented carbide wear-resistant balls are placed between parallel pressure plates of the material testing machine. A constant loading rate of 0.5 mm / min is applied until the balls break. The maximum load Fmax at the moment of breakage is recorded. Ten samples are tested in each group, and the average value is taken. Key Parameters: Loading rate 0.5 mm / min, test ambient temperature 20±5℃, pressure plate parallelism ≤0.02 mm. Data Processing: Compressive strength σ=Fmax / (πD 2 / 4), where D is the diameter of the sphere, calculate the mean ± standard deviation (n=10).

[0260] Experiment Title: Ball Milling Wear Resistance Test

[0261] Test Object: Finished multi-component cemented carbide wear-resistant balls. Test Objective: To evaluate the wear life of multi-component cemented carbide wear-resistant balls under actual ball milling conditions and verify the synergistic enhancement effect of the core-shell hard phase intermediate powder design and the radially gradient fine-grained outer layer on wear resistance. Test Principle: Simulating actual grinding conditions using a laboratory ball mill, the mass loss of the balls after a specified grinding time is measured, and the relative wear rate is calculated. Experimental Method: 5 kg of multi-component cemented carbide wear-resistant balls and 10 kg of quartz sand ore (particle size 2-5 mm) are loaded into a Φ300 mm × 300 mm laboratory ball mill. The mill is continuously ball-milled at 75% of the critical speed for 100 hours. Samples are periodically taken, cleaned, dried, and weighed to determine the cumulative wear. Three batches are tested in each group, and the average value is taken. Key Parameters: Ball-to-material mass ratio 1:2, 75% of critical speed, Mohs hardness of the ore 7, ball milling time 100 h. Data processing: Relative wear rate = (M0-Mt) / M0×100%, where M0 is the initial mass and Mt is the mass after ball milling for t hours. Calculate the mean ± standard deviation (n=3).

[0262] Experiment Title: Friction Coefficient Test

[0263] Test Object: Surface of finished multi-component cemented carbide wear-resistant balls. Test Objective: To evaluate the self-lubricating performance of multi-component cemented carbide wear-resistant balls during ball milling and to verify the role of nano-precipitations in the multi-component metal binder phase in reducing the friction coefficient. Test Principle: The friction coefficient between the multi-component cemented carbide wear-resistant ball and the mating material is determined using a ball-disc friction and wear tester. Experimental Method: The multi-component cemented carbide wear-resistant ball is used as the upper sample, and a silicon nitride ceramic disk (hardness HV1800) is used as the mating disk. Friction and wear tests are conducted under conditions of 20 N load, 0.1 m / s sliding speed, and dry friction for 30 minutes. The friction force-time curve is recorded, and the average value of 5 samples in each group is taken. Key Parameters: Load 20 N, sliding speed 0.1 m / s, test time 30 min, ambient temperature 25±2℃, relative humidity <40%RH. Data processing: The friction coefficient μ = F / N, where F is the friction force and N is the normal load. The average value ± standard deviation (n=5) of the steady-state phase (10-30 min) is taken.

[0264] Experiment Title: Density and Relative Density Test

[0265] Test Object: Finished multi-component cemented carbide wear-resistant balls. Test Objective: To evaluate the densification degree of multi-component cemented carbide wear-resistant balls and verify the effectiveness of the hot isostatic pressing densification process without a cladding under a high hard phase content and low binder phase design. Test Principle: The measured density of the balls was determined using Archimedes' displacement method, and the relative density was calculated by comparing it with the theoretical density. Experimental Method: The multi-component cemented carbide wear-resistant balls were immersed in anhydrous ethanol for 2 hours and then degassed under vacuum for 30 minutes. The mass m1 in air and the mass m2 in the immersion liquid were measured using an analytical balance with an accuracy of 0.0001g. Ten samples were tested in each group, and the average value was taken. Key Parameters: Immersion time: 2 hours; Vacuum pressure: <10 Pa; Immersion medium: anhydrous ethanol (density 0.789 g / cm³). 3 The test environment temperature was 20±2℃. Data processing: Measured density ρ=m1×ρliquid / (m1-m2), relative density=measured density / theoretical density×100%, calculate the mean ± standard deviation (n=10).

[0266] Experiment Title: Tungsten Carbide Grain Size Measurement

[0267] Test Object: Tungsten carbide phase in the outer and core regions of a multi-component cemented carbide wear-resistant ball. Test Objective: To evaluate the effect of radial gradient spherical preform design on the control of tungsten carbide grain size distribution and to verify the microstructural characteristics of fine-grained strengthening in the outer layer and coarse-grained toughening in the core. Test Principle: The metallographic structure after polishing and etching is observed using an optical microscope or scanning electron microscope. The average grain size of tungsten carbide is determined using the line section method. Experimental Method: The multi-component cemented carbide wear-resistant ball is cut along its diameter and embedded and polished. It is etched with Murakami reagent (K3Fe(CN)6 10g + KOH 10g + H2O 100mL) for 10-30 seconds to reveal grain boundaries. Metallographic photographs of the outer and core regions are taken under an optical microscope at 1000x magnification. Ten measurement lines are randomly drawn on each photograph. The grain size is statistically analyzed using the line section method. Five fields of view are tested for each region, and the average value is taken. Key parameters: Etcher Murakami reagent, etching time 10-30s, magnification 1000x, total measurement line length ≥500μm. Data processing: Average grain size d=L / N, where L is the total measurement line length and N is the number of grains intercepted. Calculate the mean ± standard deviation (n=5).

[0268] Figure 1X-ray diffraction (XRD) phase analysis images of the pre-alloyed powder preparation of the multi-metal binder phase and the nano-precipitation strengthening are shown. The parameters were fixed, with all control samples subjected to the same XRD testing conditions, scanning range, and step settings. The variable parameters were the binder phase systems: the Co-Ni-Fe-Cr-Mo pentagonal system of Example 1 and the Co-Ni-Fe ternary system of Comparative Example 1. Example 1 showed the main diffraction peaks of the face-centered cubic matrix and weak characteristic peaks or shoulder peaks related to chromium-rich or molybdenum-rich phases. Comparative Example 1 only showed matrix-related peaks and lacked the aforementioned characteristic signals. This indicates that the introduction of Cr and Mo can form identifiable precipitation-related crystalline phase characteristics during sintering, supporting the rationality of the synergistic effect of binder phase solid solution strengthening and precipitation strengthening from the perspective of phase composition.

[0269] Figure 2 XPS full-spectrum X-ray photoelectron spectroscopy (XPS) images were obtained for the preparation of multi-metal binder pre-alloyed powder and the enhancement of nano-precipitates, focusing on the surface chemical state analysis. The control samples were collected using the same XPS excitation source and energy calibration method within the same binding energy range. The variation parameters were for Example 1 and Comparative Example 1. In Example 1, besides signals such as Co, Ni, and Fe, Cr and Mo-related peaks appeared with stable peak shapes and relative intensities. Comparative Example 1 did not show Cr and Mo peaks, indicating that Cr and Mo elements were detectable in the surface chemical environment of Example 1 and made a clear chemical state contribution. This provides direct evidence for chromium- and molybdenum-rich nano-precipitates and their regulation of the electronic structure of the binder phase.

[0270] Figure 3 High-resolution X-ray photoelectron spectroscopy (XPS) spectra of Cr 2p for the preparation of pre-alloyed powders of multi-metal binder phases and the enhancement of nano-precipitates were obtained. The parameters were fixed with the same narrow-band XPS scanning energy step and pass setting, and consistent baseline processing and normalization were performed. The parameters varied between the samples used in Example 1 and Comparative Example 1. Example 1 exhibited a clear bimodal structure and possible chemical shoulder peaks in the Cr 2p binding energy region, while Comparative Example 1 showed only background signal in the same region. This indicates that Cr exists in a resolvable chemical state in Example 1 and participates in the construction of the surface chemical environment of the binder phase, thus supporting the contribution of chromium introduction to the structure and stability of the binder phase.

[0271] Figure 4High-resolution X-ray photoelectron spectroscopy (XPS) spectra of Mo 3d were obtained for the preparation of pre-alloyed powders with multi-metal binder phases and the strengthening of nano-precipitates. The parameters were fixed with the same narrow scanning window and energy resolution, and consistent intensity normalization. The parameters were varied between the samples in Example 1 and Comparative Example 1. Example 1 exhibited a typical spin-orbit splitting doublet in the Mo 3d region, while Comparative Example 1 showed no corresponding peak shape. This indicates that Mo in Example 1 possesses a stable and detectable chemical state signal, which can serve as evidence of a molybdenum-rich precipitate phase or Mo's involvement in the alloying environment. This, along with XRD and subsequent microscopic evidence, points to the effective construction of a multi-metal binder phase system.

[0272] Figure 5 This is a TEM-EDS (Transmission Electron Microscopy) combined with energy dispersive spectroscopy (EDS) characterization of nanoprecipitates prepared from multi-metal binder pre-alloyed powders and reinforced by nanoprecipitates. The parameters were fixed with the same EDS acquisition range and energy step, and the same spectral display method was used for both sets of samples. The parameters were varied between Example 1 and Comparative Example 1. In Example 1, the peak intensities related to Cr and Mo were obvious and coexisted with peaks of elements such as Co, Ni, and Fe. Comparative Example 1 lacked Cr and Mo peaks, retaining only signals of Co, Ni, and Fe. This indicates that there is indeed elemental evidence of Cr and Mo enrichment in the precipitate or its surrounding area in Example 1, which corroborates the chemical state signals shown by XPS, supporting the correctness of the reinforcement of the binder phase by chromium- and molybdenum-rich nanoprecipitates.

[0273] Figure 6 Raman spectra of vanadium carbide with a graphite shell were designed for core-shell hard phase intermediate powders. The vanadium carbide and graphite shell characterization diagrams were obtained, with fixed parameters for the same Raman excitation and spectral acquisition settings and comparisons within the same Raman shift range. The parameters were varied between Example 1 and Comparative Example 5. Example 1 was compared at approximately 800 to 1000 cm⁻¹. -1 Vanadium carbide-related features appear in the range and at approximately 1350 cm. -1 With 1580cm -1 The presence of graphite D and G peaks indicates the coexistence and structural characteristics of carbon and VC components in the shell. Comparative Example 5 shows only a weak carbon signal or lacks VC characteristics, indicating that the core-shell design does indeed introduce and retain shell evidence of VC and graphite, providing a materials science basis for the synergy of grain suppression and solid lubrication.

[0274] Figure 7Scanning electron microscopy (SEM) characterization images of the radial grain size gradient of a radially gradient spherical preform structure, featuring a fine-grained, high-hardness outer layer and a coarse-grained, high-toughness inner core, were used. Grain size was statistically analyzed using the line-cut method with fixed parameters, and compared under the same radially normalized coordinate r / R. The results were presented as a scatter plot of the mean plus or minus the standard deviation. Variations were achieved using Example 1 and Comparative Example 6 as samples. Example 1 exhibited a fine-grained level of approximately 0.40 μm in the outer region, gradually transitioning radially inward to a coarse-grained level of approximately 1.15 μm in the inner core, showing a continuously discernible gradient. Comparative Example 6, due to its excessively thin outer layer, had an insufficient fine-grained region and a coarser overall distribution. This demonstrates that the fine-grained wear-resistant outer layer and the toughening inner core of Example 1 can be synergistically constructed within the same sphere, supporting the correctness of the synergistic design of wear resistance and fracture resistance.

[0275] Figure 8 For the radial gradient spherical preform structure, an electron probe microanalysis (EPMA) was used to characterize the radial elemental distribution gradient of Co elemental distribution, resulting in a fine-grained, high-hardness outer layer and a coarse-grained, high-toughness inner core. Line scan distribution maps of Co were obtained. The parameters were fixed by using the same EPMA line scan path and step distance, and comparing samples under the same r / R coordinates. The parameters varied between Example 1 and Comparative Example 2. In Example 1, the Co mass fraction smoothly increased radially from a low value in the outer layer to a high value in the inner core, consistent with the binder phase gradient of 8 wt% in the outer layer and 16 wt% in the inner core. Comparative Example 2 showed a steeper or anomalous trend, indicating that the formulation zoning and forming strategy of Example 1 can achieve a controllable binder phase elemental gradient distribution, thus supporting the reproducible construction of gradient structures.

[0276] Figure 9 For the radially gradient spherical preform structure, an electron probe microanalysis (EPM) method was used to characterize the radial elemental distribution gradient of Ni using a fine-grained, high-hardness outer layer and a coarse-grained, high-toughness inner core. The Ni elemental distribution was characterized by a radial elemental gradient. The same line scan conditions and normalized radial position calibration were used as the fixed parameters. The samples were Example 1 and Comparative Example 2. In Example 1, Ni exhibited a gradual distribution along the radial direction consistent with the binder phase content and maintained good continuity. Comparative Example 2 showed a deviation in distribution due to gradient imbalance. This indicates that Example 1 achieved a macroscopic radial content gradient while maintaining the uniformity of the multi-component binder phase composition, which is beneficial for the synergistic effect of outer layer hardness and inner core toughness.

[0277] Figure 10For a radially gradient spherical preform structure, an electron probe microanalysis (EPMA) was used to characterize the radial elemental distribution gradient of the outer fine-grained, high-hardness layer and the inner coarse-grained, high-toughness core. The Fe elemental distribution was characterized by a radial elemental gradient. The same EPMA probe current, beam spot, and line scan length were kept constant. The parameters varied between the samples used in Example 1 and Comparative Example 2. The Fe distribution in Example 1 exhibited a smooth gradient with a lower outer layer and a higher inner layer, consistent with the trends of other binder phase elements. In contrast, the distribution in Comparative Example 2 reflected an imbalance between excessively low outer layer and excessively high inner layer. This demonstrates that the radial gradient formulation design of Example 1 can create a consistent elemental gradient on a spherical scale, providing a material basis for the zoning of overall mechanical properties.

[0278] Figure 11 For the radially gradient spherical preform structure, an electron probe microanalysis (EPM) method was used to characterize the radial elemental distribution gradient of Cr using a fine-grained, high-hardness outer layer and a coarse-grained, high-toughness inner core. Line scan distribution maps of Cr were obtained, with the same line scan and intensity correction method fixed, and compared under the same r / R coordinates. The parameters were varied between the samples in Example 1 and Comparative Example 2. In Example 1, Cr exhibited a gradient distribution consistent with the binder phase content along the radial direction, indicating that the partitioning of the outer low-binding phase and the inner high-binding phase not only changed the total amount of Cr but also carried Cr to participate in binder phase strengthening. Comparative Example 2 showed an abnormal gradient amplitude, indicating that the gradient design of Example 1 better met the requirements of stable transition and stress distribution optimization at the elemental level.

[0279] Figure 12 For a radially gradient spherical preform structure, an electron probe microanalysis (EPMA) method was used to characterize the radial elemental distribution gradient of Mo, resulting in a fine-grained, high-hardness outer layer and a coarse-grained, high-toughness inner core. Line scans of Mo were performed using this method, with the same EPMA acquisition conditions and the same scanning path. The parameters were varied between Example 1 and Comparative Example 2. In Example 1, Mo gradually increased radially from the outer layer to the core, consistent with the gradient of the multi-component binder phase. In Comparative Example 2, the Mo distribution was more uneven due to formulation imbalance. These results, along with the Mo signals from XPS and EDS, form a chain of evidence demonstrating that Mo can achieve a controllable distribution in the gradient structure and participate in the strengthening of the nano-precipitated phase, thus supporting the inherent consistency of the overall design.

[0280] Figure 13For the radially gradient spherical preform structure, an electron probe microanalysis (EPM) method was used to characterize the radial elemental distribution gradient of Co, Ni, Fe, Cr, and Mo, resulting in line scan distribution maps of the total elemental content. The parameters were fixed by summing the mass fractions of the five binder phase elements along the same line scan path and comparing them under the same r / R coordinates. The parameters varied between the samples used in Example 1 and Comparative Example 2. In Example 1, the total elemental content showed a smooth transition radially from low values ​​in the outer layer to high values ​​in the core, consistent with the binder phase content gradient of 8 wt% in the outer layer and 16 wt% in the core. In Comparative Example 2, the total elemental content varied more significantly and the transition was steeper. This indicates that the gradient scheme in Example 1 can achieve a continuous and controllable transition in both macroscopic content and microscopic elemental distribution, thus providing a reliable structural evidence chain for the synergistic effect of wear resistance in the outer layer and fracture resistance in the core.

[0281] Figure 14 The image shows a scanning electron microscope (SEM) image of the morphology of the multi-metal binder phase pre-alloyed powder from Example 1. The parameters were fixed as an inert gas atomization powder preparation process and an oxygen content controlled at 0.25 wt%, with variations in particle size distribution ranging from 10 to 75 μm. The image shows that the particles are predominantly spherical or near-spherical with high sphericity. Satellite powder structures formed by atomization flight collisions and adhesion, as well as slight surface micro-wrinkles caused by rapid solidification shrinkage, were observed. The wide particle size distribution characteristics of D10≈15 μm and D90≈70 μm confirm that this powder has a good filling performance.

[0282] Figure 15 The image shows a scanning electron microscope (SEM) image of the surface morphology of the core-shell hard phase intermediate powder from Example 1. The parameters were fixed as the WC matrix particles and the VC / graphite shell modification process, and varied as the surface state differences before and after modification. The image shows that the originally sharp polyhedral edges of the submicron to micron-sized particles have become visually rounded, and the surface exhibits a uniformly rough texture covered by fine deposits, corresponding to an extremely thin reactive shell with approximately 90% coverage. This demonstrates that the precursor structure inhibiting grain growth has been successfully constructed.

[0283] Figure 16(a) is a bright-field transmission electron microscopy (TEM) image of the cross-sectional morphology of the WC core / shell in the cemented carbide sintered body. The fixed parameters are the original WC, carbon balance control value, VC inhibitor addition of 0.5 wt%, sintering temperature of 1410°C, and holding time of 1 h. The variable parameters are the controlled slow cooling process within a specific temperature range after sintering. The image clearly shows that the WC core with complete crystal planes is uniformly covered by a continuous shell with a thickness of about 16 nm. This characteristic shell is formed by the segregation of inhibitor components under specific slow cooling conditions, proving that the process can effectively build an interfacial barrier and significantly inhibit the abnormal growth of WC grains in the later stage of liquid phase sintering. (b) is a bright-field TEM image of the morphology of the nano-precipitates in the cemented carbide binder phase. The fixed parameters are the total binder phase content of 10 wt%, the composition ratio of the multi-component binder phase, and the hot isostatic pressing (HIP) treatment conditions. The variable parameters are the aging heat treatment regime after HIP. After optimized aging treatment, near-spherical nanoprecipitates with an average size of approximately 40 nm were dispersed in the binder matrix. The interparticle spacing was moderate, and no obvious agglomeration or coarsening was observed. This demonstrates that the heat treatment successfully induced the uniform nucleation and controlled growth of the second phase in the supersaturated solid solution, resulting in a significant dispersion strengthening effect. (c) is a STEM-EDS surface scan of Cr element distribution in the binder phase region. The fixed parameters were electron beam accelerating voltage of 200 kV, beam spot size, and signal acquisition time. The variable parameter was the Cr element characteristic window selected for EDS surface scanning. The image shows that Cr element presents a significant bright enrichment region at the nanoparticle location, while the signal in the matrix region is relatively weak. This clearly indicates that the aforementioned 40 nm precipitate is a complex phase rich in Cr, proving that Cr element successfully diffused and accumulated from the matrix to specific precipitation points according to the designed path during the aging process. (d) is a STEM-EDS surface scan of Mo element distribution in the binder phase region. The fixed parameters were... Figure 16 (c) Maintaining consistency, the variable parameter is the selected Mo element feature window for EDS surface scanning. The distribution characteristics of Mo element highly overlap with those of Cr element, and it also shows a high-brightness enrichment signal at the nano-precipitation phase position, further confirming that the nano-precipitation phase is a multi-element composite strengthening phase jointly dominated by Mo and Cr, proving that the process scheme can effectively control the synergistic precipitation behavior of multi-element alloying elements to achieve composite strengthening.

[0284] As can be seen from the performance of the examples and comparative examples in Table 1, the multi-component cemented carbide wear-resistant balls of the present invention exhibit significant advantages in Vickers hardness, compressive strength, wear resistance, coefficient of friction, density, and grain size control. The Vickers hardness range of Examples 1 to 4 is HV1300 to HV1550, the compressive strength is 4500 to 5700 MPa, the ball wear rate is only 0.12% to 0.22%, the coefficient of friction is 0.28 to 0.35, and the density is 14.3 to 15.1 g / cm³. 3The outer layer grain size was controlled between 0.25 and 0.50 μm, while the core grain size was between 0.90 and 1.35 μm, forming a good radial gradient structure. In contrast, Comparative Example 1, which used only three metal elements to prepare the binder phase pre-alloyed powder, lacked the solid solution strengthening and nano-precipitation strengthening effects of chromium and molybdenum, resulting in a decrease in hardness to HV1250, a decrease in compressive strength to 4200 MPa, and an increase in wear rate to 0.35%. Comparative Example 2, due to the binder phase content exceeding the optimized range, had insufficient sintering densification caused by an excessively low outer layer binder phase, and a significant decrease in hardness and wear resistance due to an excessively high core binder phase, with a density dropping to 13.85 g / cm³. 3 The wear rate increased to 0.42% in Comparative Example 5; although it did not exceed the formulation range, the lack of core-shell hard phase intermediate powder resulted in the absence of the inhibitory effect of vanadium carbide and graphite shell on grain growth and the solid lubrication effect, leading to a wear rate of 0.26% and a friction coefficient of 0.36. Comparative Example 6, with an outer layer thickness of only 0.05R, lacked sufficient fine-grained reinforcement in the outer layer to provide effective wear protection, resulting in a significant decrease in hardness, compressive strength, and wear resistance. Comparative Examples 7 and 8, due to insufficient sintering temperature and hot isostatic pressing pressure, respectively, suffered from insufficient densification, increased porosity, and decreased grain boundary bonding strength, resulting in a density reduction to 13.6 to 13.75 g / cm³. 3 The compressive strength decreased to 3600 to 3750 MPa, and the wear rate increased to 0.45% to 0.48%, which fully verified the synergistic advantages of the technical solution of the present invention in terms of multi-metal binder phase design, core-shell hard phase intermediate powder preparation, radial gradient structure control and sintering process optimization.

[0285] Table 1 Performance Comparison Summary Table

[0286]

[0287] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-component cemented carbide wear-resistant ball, characterized in that, It includes the following components based on the total mass of the multi-component cemented carbide wear-resistant ball: The hard phase is tungsten carbide, with a mass fraction of 81 wt% to 92 wt%. The binder phase is a multi-metal binder phase with a mass fraction of 7 wt% to 18 wt%. The multi-metal binder phase is formed by sintering multi-metal binder phase pre-alloyed powder, which is prepared by alloying at least four metal elements selected from cobalt, nickel, iron, chromium and molybdenum. The added phase comprises vanadium carbide, graphite, or a combination of vanadium carbide and graphite, wherein the mass fraction of vanadium carbide is 0 wt% to 1.0 wt%, the mass fraction of graphite is 0 wt% to 0.5 wt%, and the mass fraction of at least one of vanadium carbide and graphite is greater than 0 wt%. The sum of the mass fractions of the hard phase, binder phase, vanadium carbide, and graphite is 100 wt%. Multi-metal binder phase pre-alloyed powder is prepared by the following steps: A1) Raw material preparation: Select at least four of the following metal raw material powders: cobalt, nickel, iron, chromium, and molybdenum; in the multi-metal binder phase pre-alloyed powder, the atomic percentage of the selected metal elements shall be within the corresponding ranges: cobalt 5 at% to 40 at%, nickel 5 at% to 40 at%, iron 5 at% to 40 at%, chromium 5 at% to 30 at%, and molybdenum 5 at% to 30 at; for the unselected metal elements, the atomic percentage shall be 0 at%; and the sum of the atomic percentages of all metal elements shall be 100 at%. A2) Melting: Under vacuum conditions of 1 Pa to 50 Pa or under protective atmosphere conditions, the metal raw material powder obtained in step A1 is heated to 1500°C to 1700°C and held for 10 min to 60 min to obtain a homogeneous alloy melt; the protective atmosphere is argon atmosphere or nitrogen atmosphere. A3) Atomization powder preparation: Inert gas atomization is used, with argon or nitrogen as the atomizing gas and an atomization pressure of 2MPa to 8MPa to atomize the alloy melt and obtain multi-metal binder phase pre-alloyed powder. A4) Sieving and classifying: The multi-metal binder phase pre-alloyed powder obtained in step A3 is sieved to obtain multi-metal binder phase pre-alloyed powder with a particle size of 10μm to 75μm. A5) Oxygen content control: By controlling the vacuum degree, protective atmosphere purity and atomization parameters in steps A2 and A3, the oxygen content of the obtained multi-metal binder phase pre-alloyed powder is made to be 0.01wt% to 0.50wt%, wherein the oxygen content is measured by inert gas melting-infrared absorption method.

2. The multi-component cemented carbide wear-resistant ball according to claim 1, characterized in that: The core-shell hard phase intermediate powder is a composite powder with tungsten carbide as the core and a shell containing vanadium carbide, graphite, or a combination of vanadium carbide and graphite. The mass fraction of vanadium carbide is the percentage of the total mass of vanadium carbide in the multi-element hard alloy wear-resistant ball to the total mass of the multi-element hard alloy wear-resistant ball. The total mass of vanadium carbide includes vanadium carbide in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide added in powder form. The mass fraction of graphite is the percentage of the total mass of graphite in the multi-element hard alloy wear-resistant ball to the total mass of the multi-element hard alloy wear-resistant ball. The total mass of graphite includes graphite in the shell layer of the core-shell hard phase intermediate powder and graphite added in powder form. The multi-component cemented carbide wear-resistant ball has an outer layer region and a core region along the radial direction. The outer layer region is the area extending radially inward from the outer surface of the multi-component cemented carbide wear-resistant ball, and the core region is the remaining area other than the outer layer region. The multi-component hard alloy wear-resistant ball is made by sintering and hot isostatic pressing densification of a radial gradient spherical blank. The radial gradient spherical blank is made by assembling an outer layer mixed powder and a core mixed powder with the aid of a forming binder. Both the outer layer mixed powder and the core mixed powder contain multi-component metal binder phase pre-alloy powder and tungsten carbide, and at least part of the tungsten carbide in the outer layer mixed powder is a core-shell hard phase intermediate powder.

3. The multi-component cemented carbide wear-resistant ball according to claim 2, characterized in that, Core-shell hard phase intermediate powder is prepared by the following steps: B1) Raw material preparation: Provide tungsten carbide, vanadium carbide, and graphite; B2) Proportion: Based on 100 parts by mass of tungsten carbide, 0.1 to 2.0 parts by mass of vanadium carbide and 0.05 to 0.50 parts by mass of graphite; B3) Coating and Mixing: Under a protective atmosphere, the raw materials described in step B1 are ball-milled and mixed according to the proportions described in step B2. The ball milling speed is 50 r / min to 300 r / min, the ball milling time is 1 h to 12 h, and the ball-to-powder ratio is 2:1 to 10:

1. The ball-to-powder ratio is the mass ratio of the ball milling media to the powder. The filling coefficient of the ball milling jar is 30% to 70%. The filling coefficient is the percentage of the total volume of the ball milling media and powder in the ball milling jar to the inner volume of the ball milling jar. This allows vanadium carbide and graphite to adhere to the surface of tungsten carbide particles, resulting in a coated and mixed powder. The protective atmosphere is an argon atmosphere or a nitrogen atmosphere. The ball milling media is zirconium dioxide balls. B4) Heat treatment to form a shell: Under vacuum conditions of 1 Pa to 50 Pa or under a protective atmosphere, the coated mixed powder obtained in step B3 is heated to 800°C to 1100°C and held for 0.5 h to 3.0 h to obtain a core-shell hard phase intermediate powder. B5) Shell Parameter Control: By controlling the ball milling time and ball-to-material ratio in step B3 and the heat treatment temperature and time in step B4, the shell thickness of the obtained core-shell hard phase intermediate powder is 2 nm to 30 nm and the shell coverage is 80% to 100%. The shell thickness is confirmed by transmission electron microscopy, and the shell coverage is confirmed by scanning electron microscopy or transmission electron microscopy. The shell coverage is the percentage of particles with continuous shells to the total number of particles. A continuous shell refers to a shell that is continuously coated along the surface of the tungsten carbide particles without visible interruption in the microscopic image. The oxygen content of the core-shell hard phase intermediate powder is 0.01 wt% to 0.30 wt%.

4. The multi-component cemented carbide wear-resistant ball according to claim 2, characterized in that, Radial gradient spherical preforms are prepared through the following steps: C1) Preparation of outer layer mixed powder: Based on a total mass of 100 parts by mass of the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 88.8 to 94 parts by mass of tungsten carbide, 6 to 10 parts by mass of multi-metal binder phase pre-alloyed powder, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.20 parts by mass of graphite, thus obtaining the outer layer mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the outer layer mixed powder, and all sources include vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder and vanadium carbide and graphite added in powder form; at least a portion of the tungsten carbide in the outer layer mixed powder is core-shell hard phase intermediate powder; C2) Preparation of core-mixed powder: Based on a total mass of 100 parts by mass of core-mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core-mixed powder contains 78.5 to 88 parts by mass of tungsten carbide, 12 to 20 parts by mass of multi-metal binder phase pre-alloyed powder, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.50 parts by mass of graphite, thus obtaining core-mixed powder; wherein, the mass parts of vanadium carbide and graphite are the total mass parts of vanadium carbide and graphite from all sources in the core-mixed powder, and all sources include vanadium carbide and graphite in the shell layer of the core-shell hard phase intermediate powder, as well as vanadium carbide and graphite added in powder form; C3) Granulation: Add forming binder to the outer layer mixed powder and the core mixed powder respectively, the amount of which is 0.5wt% to 4.0wt% of the mass of each mixed powder, and mix at 60℃ to 120℃ for 0.5h to 3h to obtain the outer layer granulated powder and the core granulated powder respectively. C4) Radial assembly forming: The core granulated powder and the outer granulated powder are filled into the mold in sections. By controlling the filling amount of the outer granulated powder and the core granulated powder, the outer layer thickness is 0.10 times the radius R of the radial gradient spherical blank to 0.30 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. The blank is then pressed with a pressure of 100MPa to 600MPa to obtain the radial gradient spherical blank. C5) Relative density control: The relative density of the radial gradient spherical preform is 50% to 70%. The relative density is the ratio of the measured density of the radial gradient spherical preform to its theoretical density calculated according to the formula of the outer layer mixed powder and the core mixed powder.

5. The multi-component cemented carbide wear-resistant ball according to claim 2, characterized in that, The molding adhesive is prepared by the following steps: D1) Raw material preparation: Provide paraffin wax and stearic acid; D2) Proportioning: The mass ratio of paraffin wax to stearic acid is 5:1 to 20:1; D3) Mixing preparation: Paraffin wax and stearic acid are mixed at 60℃ to 120℃ for 0.5h to 3h to obtain a molding binder; The multi-metal binder phase contains nano-precipitates with an equivalent diameter of 5 nm to 80 nm, which is the equivalent circle diameter measured in a transmission electron microscope image. The nano-precipitates are at least one of a chromium-rich phase and a molybdenum-rich phase. The nano-precipitates are characterized by transmission electron microscopy combined with energy dispersive spectroscopy, and the atomic fraction of the enriched elements in the nano-precipitates is higher than that of the corresponding elements in the multi-metal binder phase. The density of the multi-component cemented carbide wear-resistant ball is 14.0 g / cm³ to 15.3 g / cm³.

6. The multi-component cemented carbide wear-resistant ball according to claim 2, characterized in that: The thickness of the outer layer is from 0.10 times the radius R of the multi-component cemented carbide wear-resistant ball to 0.30 times the radius R of the multi-component cemented carbide wear-resistant ball, where R is the radius of the multi-component cemented carbide wear-resistant ball. Based on the mass of the outer layer region, the mass fraction of the multi-metal binder phase is 6 wt% to 10 wt%; based on the mass of the core region, the mass fraction of the multi-metal binder phase is 12 wt% to 20 wt%. The average grain size of tungsten carbide in the outer region is 0.20 μm to 0.60 μm, and the average grain size of tungsten carbide in the core region is 0.80 μm to 1.50 μm. The average grain size was measured by the line section method in the microscopic image after polishing the cross section of the multi-component cemented carbide wear-resistant ball. The diameter of the multi-component cemented carbide wear-resistant balls ranges from 5mm to 150mm.

7. The method for preparing multi-component cemented carbide wear-resistant balls as described in claim 1, characterized in that, Includes the following steps: S1) Provide a multi-metal binder phase pre-alloyed powder: Obtain a multi-metal binder phase pre-alloyed powder, wherein for at least four of the selected metal elements cobalt, nickel, iron, chromium and molybdenum, their atomic percentages are within the corresponding ranges: cobalt is 5 at% to 40 at%, nickel is 5 at% to 40 at%, iron is 5 at% to 40 at%, chromium is 5 at% to 30 at%, and molybdenum is 5 at% to 30 at, and for the unselected metal elements, their atomic percentages are 0 at%, and the sum of the atomic percentages of all metal elements is 100 at, and the particle size is 10 μm to 75 μm; S2) Powder preparation and zone mixing: Based on a total mass of 100 parts by mass of the outer layer mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the outer layer mixed powder contains 88.8 to 94 parts by mass of tungsten carbide, 6 to 10 parts by mass of the multi-metal binder pre-alloyed powder provided in step S1, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.20 parts by mass of graphite, to obtain the outer layer mixed powder; With a total mass of 100 parts by mass for the core mixed powder, and assuming the sum of the mass parts of each component is 100 parts by mass, the core mixed powder contains 78.5 to 88 parts by mass of tungsten carbide, 12 to 20 parts by mass of the multi-metal binder phase pre-alloyed powder provided in step S1, 0 to 1.0 parts by mass of vanadium carbide, and 0 to 0.50 parts by mass of graphite, to obtain the core mixed powder. S3) Granulation and Radial Assembly Forming: A forming binder is added to the outer layer mixed powder and the core mixed powder respectively, with the addition amount being 0.5wt% to 4.0wt% of the mass of each mixed powder. The mixture is mixed at 60℃ to 120℃ for 0.5h to 3h to obtain the outer layer granulated powder and the core granulated powder respectively. The core granulated powder and the outer layer granulated powder are filled into the mold in sections. By controlling the filling amount of the outer layer granulated powder and the core granulated powder in sections, the outer layer thickness is 0.10 times the radius R of the radial gradient spherical blank to 0.30 times the radius R of the radial gradient spherical blank, where R is the radius of the radial gradient spherical blank. The blank is then pressed with a pressure of 100MPa to 600MPa to obtain the radial gradient spherical blank. S4) Degreasing: Under vacuum conditions of 1 Pa to 200 Pa or under protective atmosphere conditions, the radial gradient spherical blank is heated to 200°C to 600°C and held for 0.5 h to 5 h to degrease, so that the removal rate of the forming binder reaches 90% to 100%, and the protective atmosphere is argon atmosphere or nitrogen atmosphere. S5) Sintering: Under vacuum conditions of 0.1 Pa to 50 Pa, the degreased spherical blank is heated to 1350°C to 1500°C and held for 0.5 h to 3 h for sintering; S6) Hot Isostatic Pressing Densification Treatment: The sintered spherical blank is subjected to hot isostatic pressing densification treatment under argon atmosphere at a temperature of 1300℃ to 1450℃, a pressure of 50MPa to 150MPa, and a time of 0.5h to 3h to obtain multi-component cemented carbide wear-resistant balls.

8. The preparation method according to claim 7, characterized in that: The mixing in step S2 is performed using mechanical mixing or ball milling. When ball milling is used, the milling speed is 50 r / min to 300 r / min, the milling time is 1 h to 12 h, the ball-to-powder ratio is 2:1 to 10:1 (the mass ratio of the milling media to the powder), the filling coefficient of the milling jar is 30% to 70% (the percentage of the total volume of the milling media and powder in the milling jar to the volume of the inner cavity of the milling jar), and dry ball milling is used, with zirconia balls as the milling media. When mechanical mixing is used, the mixing time is 1 h to 12 h. In step S4, the removal rate is calculated using the following formula: Removal rate = (M1-M2) / M0×100%; where M1 is the mass of the spherical blank before degreasing, M2 is the mass of the spherical blank after degreasing, M0 is the theoretical mass of the forming binder added to the spherical blank before degreasing, and M0 is calculated based on the amount of forming binder added in step S3. The vacuum sintering process in step S5 adopts the following heating curve: heating from room temperature to 1000℃ to 1200℃ at a heating rate of 5℃ / min to 15℃ / min and holding for 0.5h to 2h, then heating to 1350℃ to 1500℃ at a heating rate of 3℃ / min to 10℃ / min and holding for 0.5h to 3h. In the hot isostatic pressing densification process in step S6, the sintered spherical blank does not need to be wrapped and can be directly subjected to hot isostatic pressing densification. The absolute value of the diameter deviation of the obtained multi-component cemented carbide wear-resistant ball after grinding or polishing is no greater than 0.5 mm.

9. The application of a multi-component cemented carbide wear-resistant ball according to any one of claims 1-6 in heavy industry, characterized in that, The applications include processing ores or industrial slurries containing solid particles, with multi-component cemented carbide wear-resistant balls used as grinding media in ball mills or semi-autogenous mills.

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