A hard tungsten-based alloy material and its preparation method

Abstract

The present invention relates to the technical field of cemented carbides, and discloses a hard tungsten-based alloy material and a preparation method thereof, comprising the following raw materials in parts by mass: 90-95 parts of tungsten carbide powder, 2-3 parts of cobalt powder, 2-3 parts of nickel powder, 1-2 parts of iron powder, and 3-5 parts of modified carbon fiber. In the modified carbon fiber, the carbon fiber can be coated at the grain boundaries of tungsten carbide through a grain refiner, and the compound grain refiner inhibits the growth of tungsten carbide grains, reduces the surface energy at the grain boundaries of tungsten carbide, realizes the function of grain refinement, improves the mechanical strength of the cemented carbide, and the carbon fiber has an excellent aspect ratio and penetrates into the cemented carbide system to improve the mechanical strength of the alloy. In addition, the nano-carbon network generated by thermal decomposition grows with the carbon fiber as a template and is distributed at the grain boundaries of tungsten carbide, avoiding the decline of the mechanical properties of the cemented carbide caused by the agglomeration of the nano-carbon network.

Description

Technical Field

[0001] The present invention relates to the technical field of cemented carbides, and particularly to a hard tungsten-based alloy material and a preparation method thereof. Background Art

[0002] Cemented carbide is a composite material prepared by powder metallurgy method with refractory metal carbides (such as tungsten carbide, titanium carbide, tantalum carbide, etc.) as the hard phase and transition metal elements (such as cobalt, nickel, iron, etc.) as the binder phase. It has excellent properties such as high hardness, high strength, high toughness, wear resistance, high temperature resistance and small expansion coefficient, and is widely used in fields such as cutting, drilling, mining, tool forming and wear-resistant parts. Among them, tungsten carbide cemented carbide with tungsten carbide as the hard phase and cobalt, nickel, iron as the bonding phase is the most widely used cemented carbide at present. Tungsten carbide cemented carbide needs to add grain growth inhibitors, which can inhibit the excessive growth of grains during sintering and further enhance the mechanical properties of cemented carbide.

[0003] Adding grain refiners to tungsten carbide cemented carbide can effectively reduce the size of tungsten carbide grains. Fine grains can hinder the propagation of cracks, reduce the defects inside the alloy material, and improve the mechanical properties of cemented carbide. However, the grain refiners are prone to agglomeration and difficult to be uniformly dispersed in the alloy matrix, unable to effectively prevent grain growth, resulting in a reduction in the grain refinement effect. Moreover, tungsten carbide cemented carbide has the problem of poor tissue uniformity, with low hardness, toughness and strength, which limits the application of tungsten carbide cemented carbide. Summary of the Invention

[0004] The present invention provides a hard tungsten-based alloy material and a preparation method thereof, which solve the problems of low mechanical strength and coarse grains of tungsten carbide cemented carbide.

[0005] The technical solution of the present invention:

[0006] A hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 90-95 parts of tungsten carbide powder, 2-3 parts of cobalt powder, 2-3 parts of nickel powder, 1-2 parts of iron powder, and 3-5 parts of modified carbon fiber;

[0007] The modified carbon fiber is prepared by surface-modifying carbon fiber with a silane coupling agent and then mixing it with a composite gel;

[0008] The silane coupling agent is γ-aminopropyltriethoxysilane;

[0009] The composite gel is prepared by mixing and reacting a grain refiner modified by microcrystalline cellulose, acrylamide, N,N-methylenebisacrylamide and an initiator;

[0010] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0011] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and obtain a mixture through vacuum drying and ball milling.

[0012] S2. Place the mixture in a pressure mold to be pressed into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain a hard tungsten-based alloy material.

[0013] Further, in step S1, for the vacuum drying process: the drying temperature is 90 - 110 °C, the vacuum degree is 4 - 6 Pa, and the drying time is 10 - 15 min.

[0014] Further, in step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is (8 - 10):1, the rotation speed is 150 - 200 r / min, and the ball milling time is 20 - 24 h.

[0015] Further, in step S2, the pressing pressure is 200 - 300 MPa, and the pressing time is 40 - 50 s.

[0016] Further, in step S2, the primary sintering temperature is 1050 - 1150 °C, and the sintering time is 1 - 2 h; the secondary sintering temperature is 1380 - 1480 °C, and the sintering time is 40 - 60 min.

[0017] Further, the modified carbon fiber is specifically prepared by the following steps:

[0018] A1. Add a grain refiner and microcrystalline cellulose to ethanol, stir evenly, add ethylene glycol, stir at 70 - 80 °C for 3 - 5 h, cool to room temperature, filter, wash, and dry to obtain a grain refiner modified with microcrystalline cellulose.

[0019] A2. Add acrylamide and N,N'-methylenebisacrylamide to deionized water, after ultrasonic treatment, add the grain refiner modified with microcrystalline cellulose, stir evenly, add an initiator, stir and react at 20 - 25 °C for 30 - 40 min, take out the gel, wash the gel, and dry to obtain a composite gel.

[0020] A3. Add carbon fiber to ethanol and deionized water, stir evenly, add a silane coupling agent, stir and react at 65 - 75 °C for 1 - 2 h, cool to room temperature, filter, wash, and dry to obtain amino-functionalized carbon fiber.

[0021] A4. Add the amino-functionalized carbon fiber and the composite gel to ethanol, stir evenly, heat to 60 - 70 °C, stir for 20 - 30 min, cool to room temperature, filter, wash, and dry to obtain the modified carbon fiber.

[0022] Furthermore, during the above A1 reaction process, the hydroxyl groups contained in microcrystalline cellulose can combine with the hydroxyl groups of ethylene glycol through strong hydrogen bonds to form a cross-linked network structure. Moreover, the hydroxyl groups contained in microcrystalline cellulose and ethylene glycol can also combine with the hydroxyl groups on the surface of the grain refiner through chemical bonds, enabling microcrystalline cellulose to coat the surface of the grain refiner, and obtaining a grain refiner modified with microcrystalline cellulose.

[0023] Furthermore, during the above A2 reaction process, under the action of an initiator, acrylamide copolymerizes, and at the same time, N,N'-methylenebisacrylamide cross-links with the acrylamide molecular chains to form a three-dimensional network structure. Moreover, the active free radicals generated by the initiator enable acrylamide to also react with the hydroxyl groups on the surface of the grain refiner modified with microcrystalline cellulose, causing the grain refiner modified with microcrystalline cellulose to be embedded in the three-dimensional network structure to form a composite gel.

[0024] Furthermore, during the above A3 reaction process, the silanol groups generated by the hydrolysis of the silane coupling agent can combine with the oxygen-containing functional groups on the surface of the carbon fiber through chemical bonds, enabling the silane coupling agent to graft onto the surface of the carbon fiber and providing the carbon fiber with reactive functional groups - amino groups, which is beneficial for coating the composite gel on the surface of the carbon fiber.

[0025] Furthermore, during the above A4 reaction process, the amino groups carried on the surface of the aminated carbon fiber can combine with the hydroxyl groups and amine groups in the composite gel through chemical bonds, enabling the composite gel to adhere to the surface of the carbon fiber, obtaining modified carbon fiber, which is used as a composite grain refiner.

[0026] Furthermore, in step A1, the dosage ratio of the grain refiner, microcrystalline cellulose, ethanol, and ethylene glycol is (4 - 5) g : (1.1 - 1.3) g : (90 - 110) mL : (0.4 - 0.6) mL.

[0027] Furthermore, in step A2, the dosage ratio of acrylamide, N,N'-methylenebisacrylamide, deionized water, the grain refiner modified with microcrystalline cellulose, and the initiator is (8 - 9) g : (3.6 - 3.8) g : (90 - 110) mL : (2.6 - 3) g : (5 - 7) mL.

[0028] Furthermore, in step A3, the dosage ratio of the carbon fiber, ethanol, deionized water, and the silane coupling agent is (4 - 6) g : (25 - 35) mL : (8 - 12) mL : (1 - 2) g.

[0029] Furthermore, in step A4, the dosage ratio of the aminated carbon fiber, the composite gel, and ethanol is (4.1 - 4.3) g : (2.2 - 2.4) g : (45 - 55) mL.

[0030] Furthermore, the grain refiner is selected from any one of vanadium carbide, chromium carbide, niobium carbide, and tantalum carbide.

[0031] Furthermore, the initiator is an ammonium persulfate solution with a mass fraction of 15 - 25%.

[0032] Furthermore, the carbon fiber has a diameter of 1 - 2 µm and a length of 8 - 15 µm.

[0033] The present invention has the following beneficial effects:

[0034] (1) In the technical solution of the present invention, microcrystalline cellulose coats the grain refiner through ethylene glycol. On the one hand, the grain refiner can precipitate at the grain boundaries of tungsten carbide, playing a role in pinning the grain boundaries, inhibiting the grain boundary diffusion and surface diffusion of tungsten carbide grains, and a stable solid solution thin layer is formed at the grain boundaries by the grain refiner, reducing the precipitation of tungsten carbide grains. On the other hand, microcrystalline cellulose coats the surface of the grain refiner, which is beneficial for the grain refiner to be embedded in the composite gel system, avoiding the easy agglomeration of small-sized grain refiners, which affects the inhibition of the growth of tungsten carbide grains by the grain refiner, resulting in coarse grains of the synthesized cemented carbide and a decrease in the mechanical properties of the cemented carbide. In addition, microcrystalline cellulose can be thermally decomposed to form a carbon network structure, forming metal carbide reinforcing phases with cobalt powder, nickel powder, and iron powder, producing a combined strengthening effect of solid solution strengthening and dispersion strengthening, and increasing the mechanical properties of the cemented carbide.

[0035] (2) In the technical solution of the present invention, the grain refiner modified by microcrystalline cellulose, acrylamide, N,N - methylenebisacrylamide, and the initiator are mixed and reacted to form a composite gel with a three-dimensional network structure. On the one hand, during the preparation of the cemented carbide, the composite gel with a three-dimensional network structure is carbonized to form a dense nano-carbon network, and the grain refiner covers the surface of tungsten carbide grains, hindering grain boundary migration and atomic diffusion, and inhibiting the growth of tungsten carbide grains during sintering. On the other hand, the formed nano-carbon network serves as a bridge to connect adjacent tungsten carbide grains, strengthening the bonding between tungsten carbide grains. At the same time, the formed nano-carbon network can also absorb stress to avoid crack generation, improving the mechanical strength of the cemented carbide. In addition, the grain refiner modified by microcrystalline cellulose is embedded in the three-dimensional network structure, increasing the crosslinking density, which is beneficial for the formation of a denser nano-carbon network and improving the mechanical strength of the cemented carbide.

[0036] (3) In the technical solution of the present invention, the composite gel is coated on the surface of carbon fiber through a silane coupling agent to obtain modified carbon fiber, which is used as a composite grain refiner. On the one hand, during the preparation of cemented carbide, the grain refiner contained in the composite gel plays a role in pinning the grain boundary at the grain boundary of tungsten carbide, so that the carbon fiber can also be coated at the grain boundary of tungsten carbide through the grain refiner. The compound grain refiner inhibits the growth of tungsten carbide grains, reduces the surface energy at the grain boundary of tungsten carbide, realizes the function of grain refinement, and improves the mechanical strength of cemented carbide. On the other hand, the carbon fiber has an excellent aspect ratio, penetrates into the cemented carbide system, improves the mechanical strength of the alloy, and the nano-carbon network generated by thermal decomposition grows with the carbon fiber as a template and is distributed at the grain boundary of tungsten carbide, avoiding the decrease of the mechanical properties of cemented carbide caused by the agglomeration of the nano-carbon network. Detailed implementation mode

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0038] The raw materials used in the embodiments of the present invention are as follows, and all the reagents used are of analytical grade.

[0039] Among them, the Fisher particle size of tungsten carbide powder is 1.5 µm, purchased from Xiamen Golden Egret Special Alloy Co., Ltd.

[0040] Cobalt powder: Fisher particle size 3.5 µm, purchased from Bohuasi Nano Technology (Ningbo) Co., Ltd.

[0041] Nickel powder: Fisher particle size 2.5 µm, purchased from Shanghai Shuitian Technology Co., Ltd.

[0042] Iron powder: average particle size 2.5 µm, purchased from Ultra-fine Nano Co., Ltd.

[0043] The diameter of the carbon fiber is 1.5 µm and the length is 10 µm.

[0044] The silane coupling agent is γ-aminopropyltriethoxysilane.

[0045] The initiator is an ammonium persulfate solution with a mass fraction of 20%.

[0046] Microcrystalline cellulose is purchased from Shandong Liaocheng Luxi Pharmaceutical Excipients Co., Ltd.

[0047] The grain refiner is selected from vanadium carbide, with the product number LF-VC-W001, a particle size of 1 µm, purchased from Ningbo Luofei Nano Technology Co., Ltd.

[0048] Example 1

[0049] A hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 90 parts of tungsten carbide powder, 2 parts of cobalt powder, 2 parts of nickel powder, 1 part of iron powder, and 3 parts of modified carbon fiber;

[0050] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0051] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and obtain a mixture through vacuum drying and ball milling;

[0052] S2. Place the mixture in a pressure mold to be pressed into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain the hard tungsten-based alloy material.

[0053] Among them, in step S1, the vacuum drying process: the drying temperature is 90 °C, the vacuum degree is 4 Pa, and the drying time is 10 min;

[0054] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 8:1, the rotation speed is 150 r / min, and the ball milling time is 20 h;

[0055] In step S2, the pressing pressure is 200 MPa and the pressing time is 40 s;

[0056] In step S2, the primary sintering temperature is 1050 °C and the sintering time is 1 h; the secondary sintering temperature is 1380 °C and the sintering time is 40 min;

[0057] The modified carbon fiber is specifically prepared by the following steps:

[0058] A1. Add 4 g of vanadium carbide and 1.1 g of microcrystalline cellulose to 90 mL of ethanol, stir evenly, add 0.4 mL of ethylene glycol, stir at 70 °C for 3 h, cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 80 °C for 10 min to obtain vanadium carbide modified with microcrystalline cellulose;

[0059] A2. Add 8 g of acrylamide and 3.6 g of N,N'-methylenebisacrylamide to 90 mL of deionized water, ultrasonicate at 40 KHz for 30 min, add 2.6 g of vanadium carbide modified with microcrystalline cellulose, stir evenly, add 5 mL of a 20% ammonium persulfate solution by mass fraction, stir and react at 20 °C for 30 min to form a gel, wash the gel 3 times with deionized water, and dry at room temperature for 24 h to obtain a composite gel;

[0060] A3. Add 4 g of carbon fiber to 25 mL of ethanol and 8 mL of deionized water, stir evenly, add 1 g of γ-aminopropyltriethoxysilane, stir and react at 65 °C for 1 h, cool to room temperature, filter, wash 3 times with ethanol, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain amino-functionalized carbon fiber;

[0061] A4. Add 4.1 g of amino-functionalized carbon fiber and 2.2 g of composite gel to 45 mL of ethanol, stir evenly, heat to 60 °C, stir and mix for 20 min, cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain modified carbon fiber.

[0062] Example 2

[0063] A hard tungsten-based alloy material includes the following raw materials in parts by mass: 93 parts of tungsten carbide powder, 2.5 parts of cobalt powder, 2.5 parts of nickel powder, 1.5 parts of iron powder, and 4 parts of modified carbon fiber;

[0064] A preparation method of a hard tungsten-based alloy material includes the following preparation steps:

[0065] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and perform vacuum drying and ball milling to obtain a mixture;

[0066] S2. Place the mixture in a pressure mold to press into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain a hard tungsten-based alloy material.

[0067] Among them, in step S1, the vacuum drying process: the drying temperature is 100 °C, the vacuum degree is 5 Pa, and the drying time is 13 min;

[0068] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 9:1, the rotation speed is 180 r / min, and the ball milling time is 22 h;

[0069] In step S2, the pressing pressure is 250 MPa and the pressing time is 45 s;

[0070] In step S2, the primary sintering temperature is 1100 °C and the sintering time is 1.5 h; the secondary sintering temperature is 1430 °C and the sintering time is 50 min.

[0071] The modified carbon fiber is specifically prepared by the following steps:

[0072] A1. Add 4.5 g of vanadium carbide and 1.2 g of microcrystalline cellulose to 100 mL of ethanol, stir evenly, add 0.5 mL of ethylene glycol, stir at 75 °C for 4 h, cool to room temperature, filter, wash with deionized water three times, and dry in an oven at 80 °C for 10 min to obtain vanadium carbide modified by microcrystalline cellulose;

[0073] A2. Add 8.5 g of acrylamide and 3.7 g of N,N-methylenebisacrylamide to 100 mL of deionized water, ultrasonicate at 40 KHz for 30 min, add 2.8 g of vanadium carbide modified by microcrystalline cellulose, stir evenly, add 6 mL of a 20% ammonium persulfate solution by mass fraction, stir and react at 23 °C for 35 min to form a gel, wash the gel with deionized water three times, and dry at room temperature for 24 h to obtain a composite gel;

[0074] A3. Add 5 g of carbon fiber to 30 mL of ethanol and 10 mL of deionized water, stir evenly, add 1.5 g of γ-aminopropyltriethoxysilane, stir and react at 70 °C for 1.5 h, cool to room temperature, filter, wash with ethanol three times, wash with deionized water three times, and dry in an oven at 70 °C for 10 min to obtain amino-functionalized carbon fiber;

[0075] A4. Add 4.2 g of amino-functionalized carbon fiber and 2.3 g of composite gel to 50 mL of ethanol, stir evenly, heat to 65 °C, stir and mix for 25 min, cool to room temperature, filter, wash with deionized water three times, and dry in an oven at 70 °C for 10 min to obtain modified carbon fiber.

[0076] Example 3

[0077] A kind of hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 95 parts of tungsten carbide powder, 3 parts of cobalt powder, 3 parts of nickel powder, 2 parts of iron powder, and 5 parts of modified carbon fiber;

[0078] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0079] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, carry out vacuum drying and ball milling to obtain a mixture;

[0080] S2. Place the mixture in a pressure mold to press into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain a hard tungsten-based alloy material.

[0081] Among them, in step S1, the vacuum drying process: the drying temperature is 110 °C, the vacuum degree is 6 Pa, and the drying time is 15 min;

[0082] In step S1, ball milling is carried out using a ball mill, with a ball-to-material ratio of 10:1, a rotation speed of 200 r / min, and a ball milling time of 24 h;

[0083] In step S2, the pressing pressure is 300 MPa and the pressing time is 50 s;

[0084] In step S2, the primary sintering temperature is 1150 °C and the sintering time is 2 h; the secondary sintering temperature is 1480 °C and the sintering time is 60 min.

[0085] The modified carbon fiber is specifically prepared by the following steps:

[0086] A1. Add 5 g of vanadium carbide and 1.3 g of microcrystalline cellulose to 110 mL of ethanol, stir evenly, add 0.6 mL of ethylene glycol, stir at 80 °C for 5 h, cool to room temperature, filter, wash with deionized water 3 times, and dry in an 80 °C oven for 10 min to obtain vanadium carbide modified by microcrystalline cellulose;

[0087] A2. Add 9 g of acrylamide and 3.8 g of N,N-methylenebisacrylamide to 110 mL of deionized water, ultrasonicate at 40 KHz for 30 min, add 3 g of vanadium carbide modified by microcrystalline cellulose, stir evenly, add 7 mL of a 20% ammonium persulfate solution by mass fraction, stir and react at 25 °C for 40 min to form a gel, wash the gel with deionized water 3 times, and dry at room temperature for 24 h to obtain a composite gel;

[0088] A3. Add 6 g of carbon fiber to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 2 g of γ-aminopropyltriethoxysilane, stir and react at 75 °C for 2 h, cool to room temperature, filter, wash with ethanol 3 times, wash with deionized water 3 times, and dry in a 70 °C oven for 10 min to obtain amino-functionalized carbon fiber;

[0089] A4. Add 4.3 g of amino-functionalized carbon fiber and 2.4 g of the composite gel to 55 mL of ethanol, stir evenly, heat to 70 °C, stir and mix for 30 min, cool to room temperature, filter, wash with deionized water 3 times, and dry in a 70 °C oven for 10 min to obtain the modified carbon fiber.

[0090] Comparative Example 1

[0091] A hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 95 parts of tungsten carbide powder, 3 parts of cobalt powder, 3 parts of nickel powder, 2 parts of iron powder, and 5 parts of modified carbon fiber;

[0092] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0093] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and obtain a mixture through vacuum drying and ball milling.

[0094] S2. Place the mixture in a pressure mold to press it into a preform, and then place the preform in a sintering furnace for primary sintering, secondary sintering, and cool it to room temperature to obtain a hard tungsten-based alloy material.

[0095] Among them, in step S1, for the vacuum drying process: the drying temperature is 110 °C, the vacuum degree is 6 Pa, and the drying time is 15 min.

[0096] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 10:1, the rotation speed is 200 r / min, and the ball milling time is 24 h.

[0097] In step S2, the pressing pressure is 300 MPa and the pressing time is 50 s.

[0098] In step S2, the primary sintering temperature is 1150 °C and the sintering time is 2 h; the secondary sintering temperature is 1480 °C and the sintering time is 60 min.

[0099] The modified carbon fiber is specifically prepared by the following steps:

[0100] A1. Add 9 g of acrylamide and 3.8 g of N,N'-methylenebisacrylamide to 110 mL of deionized water, ultrasonicate for 30 min at 40 KHz, add 3 g of vanadium carbide, stir evenly, add 7 mL of a 20% ammonium persulfate solution, stir and react at 25 °C for 40 min to form a gel. Wash the gel 3 times with deionized water and dry it at room temperature for 24 h to obtain a composite gel.

[0101] A2. Add 6 g of carbon fiber to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 2 g of γ-aminopropyltriethoxysilane, stir and react at 75 °C for 2 h, cool to room temperature, filter, wash 3 times with ethanol, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain amino-functionalized carbon fiber.

[0102] A3. Add 4.3 g of amino-functionalized carbon fiber and 2.4 g of composite gel to 55 mL of ethanol, stir evenly, heat to 70 °C, stir and mix for 30 min, cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain modified carbon fiber.

[0103] Comparative Example 2

[0104] A hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 95 parts of tungsten carbide powder, 3 parts of cobalt powder, 3 parts of nickel powder, 2 parts of iron powder, and 5 parts of modified carbon fiber.

[0105] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0106] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and after vacuum drying and ball milling, obtain a mixed material;

[0107] S2. Place the mixed material in a pressure mold to be pressed into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain the hard tungsten-based alloy material.

[0108] Among them, in step S1, the vacuum drying process: the drying temperature is 110 °C, the vacuum degree is 6 Pa, and the drying time is 15 min;

[0109] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 10:1, the rotation speed is 200 r / min, and the ball milling time is 24 h;

[0110] In step S2, the pressing pressure is 300 MPa and the pressing time is 50 s;

[0111] In step S2, the primary sintering temperature is 1150 °C and the sintering time is 2 h; the secondary sintering temperature is 1480 °C and the sintering time is 60 min.

[0112] The modified carbon fiber is specifically prepared by the following steps:

[0113] A1. Add 5 g of vanadium carbide and 1.3 g of microcrystalline cellulose to 110 mL of ethanol, stir evenly, add 0.6 mL of ethylene glycol, stir at 80 °C for 5 h, cool to room temperature, filter, wash with deionized water 3 times, and dry in an 80 °C oven for 10 min to obtain vanadium carbide modified by microcrystalline cellulose;

[0114] A2. Add 12.8 g of acrylamide to 110 mL of deionized water, ultrasonicate at 40 KHz for 30 min, add 3 g of the grain refiner modified by microcrystalline cellulose, stir evenly, add 7 mL of a 20% ammonium persulfate solution by mass fraction, stir and react at 25 °C for 40 min to form a gel, wash the gel with deionized water 3 times, and dry at room temperature for 24 h to obtain a composite gel;

[0115] A3. Add 6 g of carbon fiber to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 2 g of γ-aminopropyltriethoxysilane, stir and react at 75 °C for 2 h, cool to room temperature, filter, wash with ethanol 3 times, wash with deionized water 3 times, and dry in a 70 °C oven for 10 min to obtain amino-functionalized carbon fiber;

[0116] A4. Add 4.3 g of aminated carbon fiber and 2.4 g of composite gel to 55 mL of ethanol, stir evenly, heat up to 70 °C, stir and mix for 30 min, cool to room temperature, filter, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified carbon fiber.

[0117] Comparative Example 3

[0118] A hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 95 parts of tungsten carbide powder, 3 parts of cobalt powder, 3 parts of nickel powder, 2 parts of iron powder, and 5 parts of modified carbon fiber;

[0119] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0120] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and obtain a mixture through vacuum drying and ball milling;

[0121] S2. Place the mixture in a pressure mold to be pressed into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain a hard tungsten-based alloy material.

[0122] Among them, in step S1, the vacuum drying process: the drying temperature is 110 °C, the vacuum degree is 6 Pa, and the drying time is 15 min;

[0123] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 10:1, the rotation speed is 200 r / min, and the ball milling time is 24 h;

[0124] In step S2, the pressing pressure is 300 MPa and the pressing time is 50 s;

[0125] In step S2, the primary sintering temperature is 1150 °C and the sintering time is 2 h; the secondary sintering temperature is 1480 °C and the sintering time is 60 min.

[0126] The modified carbon fiber is specifically prepared by the following steps:

[0127] A1. Add 5 g of vanadium carbide and 1.3 g of microcrystalline cellulose to 110 mL of ethanol, stir evenly, add 0.6 mL of ethylene glycol, stir at 80 °C for 5 h, cool to room temperature, filter, wash with deionized water 3 times, and dry in an oven at 80 °C for 10 min to obtain microcrystalline cellulose-modified vanadium carbide;

[0128] A2. Add 12.8 g of N,N-methylenebisacrylamide to 110 mL of deionized water, sonicate for 30 min at 40 KHz, add 3 g of a grain refiner modified with microcrystalline cellulose, stir evenly, add 7 mL of a 20% ammonium persulfate solution, and stir and react at 25 °C for 40 min to form a gel. Wash the gel 3 times with deionized water and dry at room temperature for 24 h to obtain a composite gel;

[0129] A3. Add 6 g of carbon fiber to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 2 g of γ-aminopropyltriethoxysilane, stir and react at 75 °C for 2 h, cool to room temperature, filter, wash 3 times with ethanol, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain amino-functionalized carbon fiber;

[0130] A4. Add 4.3 g of amino-functionalized carbon fiber and 2.4 g of the composite gel to 55 mL of ethanol, stir evenly, heat to 70 °C, stir and mix for 30 min, cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 min to obtain modified carbon fiber.

[0131] Comparative Example 4

[0132] A kind of hard tungsten-based alloy material, comprising the following raw materials in parts by mass: 95 parts of tungsten carbide powder, 3 parts of cobalt powder, 3 parts of nickel powder, 2 parts of iron powder, and 5 parts of modified carbon fiber;

[0133] A preparation method of a hard tungsten-based alloy material, comprising the following preparation steps:

[0134] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and obtain a mixture through vacuum drying and ball milling;

[0135] S2. Place the mixture in a pressure mold to be pressed into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain the hard tungsten-based alloy material.

[0136] Among them, in step S1, the vacuum drying process: the drying temperature is 110 °C, the vacuum degree is 6 Pa, and the drying time is 15 min;

[0137] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 10:1, the rotation speed is 200 r / min, and the ball milling time is 24 h;

[0138] In step S2, the pressing pressure is 300 MPa and the pressing time is 50 s;

[0139] In step S2, the primary sintering temperature is 1150 °C and the sintering time is 2 h; the secondary sintering temperature is 1480 °C and the sintering time is 60 min.

[0140] The modified carbon fiber is specifically prepared by the following steps:

[0141] A1. Add 5 g of vanadium carbide and 1.3 g of microcrystalline cellulose to 110 mL of ethanol, stir evenly, add 0.6 mL of ethylene glycol, stir at 80 °C for 5 h, cool to room temperature, filter, wash with deionized water 3 times, and dry in an oven at 80 °C for 10 min to obtain vanadium carbide modified by microcrystalline cellulose;

[0142] A2. Add 6 g of carbon fiber to 35 mL of ethanol and 12 mL of deionized water, stir evenly, add 2 g of γ-aminopropyltriethoxysilane, stir and react at 75 °C for 2 h, cool to room temperature, filter, wash with ethanol 3 times, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain amino-functionalized carbon fiber;

[0143] A3. Add 4.3 g of amino-functionalized carbon fiber and 2.4 g of vanadium carbide modified by microcrystalline cellulose to 55 mL of ethanol, stir evenly, heat to 70 °C, stir and mix for 30 min, cool to room temperature, filter, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain modified carbon fiber.

[0144] Comparative Example 5

[0145] A hard tungsten-based alloy material includes the following raw materials in parts by mass: 95 parts of tungsten carbide powder, 3 parts of cobalt powder, 3 parts of nickel powder, 2 parts of iron powder, and 5 parts of modified carbon fiber;

[0146] A preparation method of a hard tungsten-based alloy material includes the following preparation steps:

[0147] S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and perform vacuum drying and ball milling to obtain a mixed material;

[0148] S2. Place the mixed material in a pressure mold to be pressed into a preform, and then place the preform in a sintering furnace for primary sintering and secondary sintering, and cool to room temperature to obtain a hard tungsten-based alloy material.

[0149] Among them, in step S1, the vacuum drying process: the drying temperature is 110 °C, the vacuum degree is 6 Pa, and the drying time is 15 min;

[0150] In step S1, ball milling is carried out using a ball mill, the ball-to-material ratio is 10:1, the rotation speed is 200 r / min, and the ball milling time is 24 h;

[0151] In step S2, the pressing pressure is 300 MPa and the pressing time is 50 s;

[0152] In step S2, the primary sintering temperature is 1150°C and the sintering time is 2 h; the secondary sintering temperature is 1480°C and the sintering time is 60 min.

[0153] The modified carbon fiber is specifically prepared by the following steps:

[0154] A1. Add 5 g of vanadium carbide and 1.3 g of microcrystalline cellulose to 110 mL of ethanol, stir evenly, add 0.6 mL of ethylene glycol, stir at 80°C for 5 h, cool to room temperature, filter, wash with deionized water 3 times, and dry in an oven at 80°C for 10 min to obtain vanadium carbide modified by microcrystalline cellulose;

[0155] A2. Add 9 g of acrylamide and 3.8 g of N,N-methylenebisacrylamide to 110 mL of deionized water, ultrasonicate at 40 KHz for 30 min, add 3 g of the grain refiner modified by microcrystalline cellulose, stir evenly, add 7 mL of a 20% ammonium persulfate solution by mass fraction, stir and react at 25°C for 40 min to form a gel, wash the gel with deionized water 3 times, and dry at room temperature for 24 h to obtain a composite gel;

[0156] A3. Add 4.3 g of carbon fiber and 2.4 g of the composite gel to 55 mL of ethanol, stir evenly, heat to 70°C, stir and mix for 30 min, cool to room temperature, filter, wash with deionized water 3 times, and dry in an oven at 70°C for 10 min to obtain the modified carbon fiber.

[0157] Now, the performance of the hard tungsten-based alloy materials prepared in Examples 1-3 and Comparative Examples 1-5 is tested.

[0158] Density test: The test is carried out in accordance with the standard GB / T3850-2015. Measure 3 different positions of the hard tungsten-based alloy material and take the average value.

[0159] Hardness (HRA) test: Test the hardness value of the above-prepared hard tungsten-based alloy material in accordance with the standard GB / T3849.1-2015.

[0160] Average grain size test: Test the average grain size of the above-prepared hard tungsten-based alloy material in accordance with the standards GB / T3488.2-2018 and ISO4499-2:2008.

[0161] Mechanical property test: Test the flexural strength of the above-prepared hard tungsten-based alloy material in accordance with the standard GB / T6569-2006. The specimen size is 3 mm × 4 mm × 36 mm, and the loading rate is 0.5 mm / min; test the impact toughness of the above-prepared hard tungsten-based alloy material in accordance with the standard GB / T1817-2017.

[0162] The test results are shown in Table 1.

[0163] Table 1 Performance Detection of Hard Tungsten-Based Alloy Materials Prepared in Examples 1-3 and Comparative Examples 1-5

[0164]

[0165] It can be seen from the data in Table 1 that the hard tungsten-based alloy materials prepared in Examples 1-3 have high mechanical strength and small grain size.

[0166] In Comparative Example 1, the modified carbon fiber prepared by replacing vanadium carbide modified with microcrystalline cellulose with vanadium carbide was added to the hard tungsten-based alloy material, and its mechanical properties decreased and the grain size increased, proving that microcrystalline cellulose coated on the surface of vanadium carbide is beneficial to the embedding of vanadium carbide into the composite gel system, avoiding the easy agglomeration of small-sized grain refiners, affecting the inhibition of the growth of tungsten carbide grains by grain refiners, resulting in a decrease in the mechanical properties of the hard alloy, and microcrystalline cellulose can be thermally decomposed to form a carbon network structure, forming metal carbide strengthening phases with cobalt powder, nickel powder, and iron powder, producing a combined strengthening effect of solid solution strengthening and dispersion strengthening, and increasing the mechanical properties of the hard alloy.

[0167] In Comparative Example 2, only acrylamide was selected, and in Comparative Example 3, only N,N-methylenebisacrylamide was selected to prepare the modified carbon fiber and added to the hard tungsten-based alloy material, and its mechanical properties decreased, proving that acrylamide copolymerizes, and at the same time N,N-methylenebisacrylamide crosslinks with the acrylamide molecular chain to form a three-dimensional network structure, which is beneficial to the formation of a dense nano-carbon network in the tungsten carbide alloy, inhibiting the growth of tungsten carbide grains during sintering, and improving the mechanical strength of the hard alloy.

[0168] In Comparative Example 4, the modified carbon fiber prepared by replacing the composite gel with vanadium carbide modified with microcrystalline cellulose was added to the hard tungsten-based alloy material, and its mechanical properties decreased, proving that the three-dimensional network structure formed by vanadium carbide modified with microcrystalline cellulose, acrylamide, and N,N-methylenebisacrylamide can form a dense nano-carbon network covering the surface of tungsten carbide grains, hindering grain boundary migration and atomic diffusion, and inhibiting the growth of tungsten carbide grains during sintering; the formed nano-carbon network acts as a bridge to connect adjacent tungsten carbide grains and absorbs stress to avoid crack generation, improving the mechanical strength of the hard alloy.

[0169] In Comparative Example 5, the modified carbon fiber prepared by replacing the aminated carbon fiber with carbon fiber was added to the hard tungsten-based alloy material, and its mechanical properties decreased, proving that the composite gel is coated on the surface of the carbon fiber through a silane coupling agent, enabling the carbon fiber to be coated at the grain boundaries of tungsten carbide, achieving the effect of grain refinement, improving the mechanical strength of the hard alloy, and the nano-carbon network generated by thermal decomposition grows with the carbon fiber as a template and is distributed at the grain boundaries of tungsten carbide, avoiding the agglomeration of the nano-carbon network leading to a decrease in the mechanical properties of the hard alloy.

[0170] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0171] The above content is only an example and explanation of the present invention. Those skilled in the art of the present technology may make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A hard tungsten-based alloy material, characterized in that, It includes the following raw materials in parts by mass: 90 - 95 parts of tungsten carbide powder, 2 - 3 parts of cobalt powder, 2 - 3 parts of nickel powder, 1 - 2 parts of iron powder, and 3 - 5 parts of modified carbon fiber; The preparation method of the hard tungsten - based alloy material is specifically obtained by the following steps: S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and after vacuum drying and ball - milling, obtain a mixed material; S2. Place the mixed material in a pressure mold to press - form a pre - formed body, and then place the pre - formed body in a sintering furnace. Conduct a first sintering at 1050 - 1150 °C for 1 - 2 h, and a second sintering at 1380 - 1480 °C for 40 - 60 min, and cool to room temperature to obtain the hard tungsten - based alloy material; The modified carbon fiber is prepared by surface - modifying carbon fiber with a silane coupling agent and then mixing it with a composite gel; The silane coupling agent is γ - aminopropyltriethoxysilane; The composite gel is prepared by mixing and reacting a grain refiner modified with microcrystalline cellulose, acrylamide, N,N - methylenebisacrylamide and an initiator; The modified carbon fiber is specifically prepared by the following steps: A1. Add the grain refiner and microcrystalline cellulose to ethanol, stir evenly, add ethylene glycol, stir at 70 - 80 °C for 3 - 5 h, cool to room temperature, filter, wash, and dry to obtain the grain refiner modified with microcrystalline cellulose; A2. Add acrylamide and N,N - methylenebisacrylamide to deionized water, after ultrasonic treatment, add the grain refiner modified with microcrystalline cellulose, stir evenly, add the initiator, stir and react at 20 - 25 °C for 30 - 40 min, take out the gel, wash the gel, and dry to obtain the composite gel; A3. Add carbon fiber to ethanol and deionized water, stir evenly, add the silane coupling agent, stir and react at 65 - 75 °C for 1 - 2 h, cool to room temperature, filter, wash, and dry to obtain amino - modified carbon fiber; A4. Add the amino - modified carbon fiber and the composite gel to ethanol, stir evenly, heat up to 60 - 70 °C, stir for 20 - 30 min, cool to room temperature, filter, wash, and dry to obtain the modified carbon fiber.

2. A hard tungsten-based alloy material according to claim 1, characterized in that, In step A1, the dosage ratio of the grain refiner, microcrystalline cellulose, ethanol and ethylene glycol is (4 - 5) g:(1.1 - 1.3) g:(90 - 110) mL:(0.4 - 0.6) mL.

3. A hard tungsten-based alloy material according to claim 1, characterized in that, In step A2, the dosage ratio of acrylamide, N,N - methylenebisacrylamide, deionized water, the grain refiner modified with microcrystalline cellulose and the initiator is (8 - 9) g:(3.6 - 3.8) g:(90 - 110) mL:(2.6 - 3) g:(5 - 7) mL.

4. A hard tungsten-based alloy material according to claim 1, characterized in that, In step A3, the dosage ratio of carbon fiber, ethanol, deionized water and the silane coupling agent is (4 - 6) g:(25 - 35) mL:(8 - 12) mL:(1 - 2) g.

5. A hard tungsten-based alloy material according to claim 1, characterized in that, In step A4, the dosage ratio of the amino - modified carbon fiber, the composite gel and ethanol is (4.1 - 4.3) g:(2.2 - 2.4) g:(45 - 55) mL.

6. A hard tungsten-based alloy material according to claim 1, characterized in that, The grain refiner is selected from any one of vanadium carbide, chromium carbide, niobium carbide, tantalum carbide.

7. A hard tungsten-based alloy material according to claim 1, characterized in that The initiator is an ammonium persulfate solution with a mass fraction of 15 - 25%.

8. A hard tungsten-based alloy material according to claim 1, characterized in that The carbon fiber has a diameter of 1 - 2 µm and a length of 8 - 15 µm.

9. A method for preparing a hard tungsten-based alloy material as described in any one of claims 1-8, characterized in that, It includes the following preparation steps: S1. Mix tungsten carbide powder, cobalt powder, nickel powder, iron powder and modified carbon fiber, and obtain a mixture through vacuum drying and ball milling; S2. Place the mixture in a pressure mold to press into a preform, then place the preform in a sintering furnace, conduct primary sintering at 1050 - 1150 °C for 1 - 2 h, conduct secondary sintering at 1380 - 1480 °C for 40 - 60 min, and cool to room temperature to obtain a hard tungsten-based alloy material.

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