An ultrafine cemented carbide cutting tool and its preparation method

Abstract

The present invention relates to an ultra-fine cemented carbide cutting tool and a preparation method thereof, belonging to the technical field of cemented carbide products, and comprising the following steps: ball-milling and sieving tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder to obtain a cemented carbide powder body; subjecting the cemented carbide powder body to spark plasma sintering and then to vacuum heat treatment to obtain an ultra-fine cemented carbide cutting tool; in the technical solution of the present invention, a modified cobalt powder is prepared by mixing a vanadium source, a yttrium source and a cobalt source through a spray conversion method; a reinforced composite powder is prepared by combining nanoparticles and a reinforcing material through electrostatic adsorption; the modified cobalt powder and the reinforced composite powder can not only inhibit the growth of tungsten carbide grains, but also effectively improve the hardness, flexural strength and fracture toughness of the cemented carbide, further improve the mechanical properties, thermal stability and wear resistance of the ultra-fine cemented carbide cutting tool, overall improve the comprehensive performance of the ultra-fine cemented carbide cutting tool, and extend its service life.

Description

Technical Field

[0001] The present invention belongs to the technical field of cemented carbide products, and specifically, relates to an ultra-fine cemented carbide cutting tool and a preparation method thereof. Background Art

[0002] As one of the core materials in modern manufacturing, cemented carbide is an alloy material made from refractory metal hard compounds (such as WC) and binder metals (such as Co) through powder metallurgy process. It has the characteristics of high hardness, relatively good strength and toughness, and also has excellent properties such as certain heat resistance and corrosion resistance. Due to the characteristics of cemented carbide, it is mainly used to manufacture cutting tools and wear-resistant parts, and also has a wide range of applications in mechanical processing fields such as aerospace, automotive, and molds. Traditional cemented carbide cutting tools have an inherent contradiction between strength and hardness. Generally, the higher the hardness, the lower the strength, and the higher the strength, the lower the hardness. However, in many occasions of mechanical processing, it is required that cemented carbide cutting tools need to have excellent comprehensive properties of high strength and high hardness. Therefore, ultra-fine cemented carbide has become an important development direction of cemented carbide, and its hardness and strength are improved simultaneously through fine grain strengthening.

[0003] Currently, the preparation of ultra-fine cemented carbide cutting tools still has the following defects: ultra-fine tungsten carbide is prone to abnormal grain growth during liquid phase sintering, resulting in a decrease in the hardness and wear resistance of the cutting tool. By adding grain growth inhibitors (such as Cr3C2, VC, TiC, etc.), the abnormal grain growth of tungsten carbide can be effectively controlled. However, due to the local aggregation of grain growth inhibitors, the flexural strength and fracture toughness of ultra-fine cemented carbide cutting tools will decrease significantly, making it difficult to meet the requirements of high-efficiency cutting; and due to the easy oxidation and softening of cobalt at high temperatures, the overall strength of cemented carbide decreases, shortening the service life of ultra-fine cemented carbide cutting tools and further affecting the final performance and quality of the product. Summary of the Invention

[0004] The object of the present invention is to provide an ultrafine cemented carbide tool and a preparation method thereof. By ball-milling and sieving tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforcing composite powder, a cemented carbide powder body is obtained. After subjecting the cemented carbide powder body to spark plasma sintering and then vacuum heat treatment, an ultrafine cemented carbide tool is finally obtained. The modified cobalt powder is prepared by spray conversion method by mixing a vanadium source, a yttrium source and a cobalt source. The reinforcing composite powder is prepared by electrostatic adsorption to combine nanoparticles with a reinforcing material. The modified cobalt powder can not only effectively inhibit the growth of tungsten carbide grains, improve the strength and fracture toughness of the cemented carbide, but also enhance the hardness and wear resistance of the ultrafine cemented carbide tool. Both the nanoparticles and the reinforcing material in the reinforcing composite powder have a synergistic effect, which can better improve the fracture toughness and wear resistance of the cemented carbide, and enhance the wear resistance, corrosion resistance and thermal stability of the cemented carbide. The finally prepared ultrafine cemented carbide tool has good mechanical properties, wear resistance and thermal stability, can extend the service life of the ultrafine cemented carbide tool, and has good overall comprehensive performance.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of an ultrafine cemented carbide tool, comprising the following steps:

[0007] S1: Ball-mill and sieve tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforcing composite powder to obtain a cemented carbide powder body;

[0008] S2: Subject the cemented carbide powder body in step S1 to spark plasma sintering and then vacuum heat treatment to obtain an ultrafine cemented carbide tool;

[0009] Wherein, the modified cobalt powder is prepared by spray conversion method by mixing a vanadium source, a yttrium source and a cobalt source;

[0010] The reinforcing composite powder is prepared by electrostatic adsorption to combine nanoparticles with a reinforcing material.

[0011] Further, step S1 is specifically:

[0012] Add polyvinylpyrrolidone and absolute ethanol into a reaction kettle, stir at 50-60 °C for 25-35 min, then add tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforcing composite powder under nitrogen protection, stir for 15-25 min, then perform ultrasonic dispersion for 25-35 min, then perform ball-milling for 46-50 h under nitrogen protection. After the ball-milling is completed, vacuum dry at 55-65 °C and sieve through a 400-500 mesh sieve to obtain a cemented carbide powder body.

[0013] Further, the mass ratio of the polyvinylpyrrolidone, absolute ethanol, tungsten carbide powder, titanium carbide powder, modified cobalt powder, and reinforcing composite powder is 0.01 - 0.03: 15 - 25: 0.9 - 1.1: 0.1 - 0.2: 0.15 - 0.25: 0.05 - 0.15.

[0014] Further, the preparation method of the modified cobalt powder includes the following steps:

[0015] Add a vanadium source, a yttrium source, and a cobalt source to deionized water, and stir at 55 - 65 °C for 25 - 35 min to obtain a mixed solution. Spray-convert the mixed solution to obtain a precursor powder. Calcinate the precursor powder at 295 - 305 °C for 1 - 2 h to obtain an oxide powder. Reduce the oxide powder with hydrogen at 495 - 505 °C for 1 - 2 h to finally obtain the modified cobalt powder.

[0016] In the above reaction process, the spray-conversion method is used to add the vanadium source and the yttrium source to the cobalt source in the form of a solution. After calcination, the vanadium source is oxidized to vanadium pentoxide, the yttrium source is oxidized to yttrium oxide, and the cobalt source is oxidized to cobalt tetroxide. After reduction with hydrogen, vanadium pentoxide is reduced to vanadium, yttrium oxide is not easily reduced, and cobalt tetroxide is reduced to cobalt. Finally, a modified cobalt powder containing vanadium and yttrium oxide is obtained.

[0017] Further, the mass ratio of the vanadium source, the yttrium source, the cobalt source, and deionized water is 1 - 2: 1 - 2: 92 - 93: 450 - 550.

[0018] Further, the vanadium source is ammonium metavanadate; the yttrium source is yttrium acetate hydrate; the cobalt source is cobalt acetate tetrahydrate.

[0019] Further, the inlet temperature of the spray conversion is 215 - 225 °C, and the outlet temperature is 125 - 135 °C.

[0020] Further, the preparation method of the reinforcing composite powder includes the following steps:

[0021] Add a reinforcing material to deionized water and ultrasonically disperse for 4 - 5 h to obtain dispersion liquid A; add nanoparticles to deionized water, then add a hydrochloric acid solution to adjust the pH value to 3 - 3.5, and then ultrasonically treat for 2 - 3 h to obtain dispersion liquid B; add dispersion liquid B to dispersion liquid A and stir for 1 - 2 h, and finally freeze-dry at -50 - -40 °C to obtain the reinforcing composite powder.

[0022] During the above reaction process, the surface of the reinforcing material is negatively charged in the aqueous solution, and the surface of the nanoparticles is positively charged in the aqueous solution. The negative charge on the surface of the reinforcing material can be combined with the positive charge on the surface of the nanoparticles through electrostatic adsorption, thereby binding the nanoparticles to the reinforcing material. After freeze-drying, the reinforced composite powder is finally obtained.

[0023] Further, the mass ratio of the reinforcing material to deionized water is 3.5 - 4.5: 800 - 1000.

[0024] Further, the reinforcing material is composed of graphene oxide and hydroxylated boron nitride nanosheets mixed in a mass ratio of 0.9 - 1.1: 0.7 - 0.8.

[0025] Further, the mass ratio of the nanoparticles to deionized water is 5.5 - 6.5: 1000 - 1200.

[0026] Further, the nanoparticles are composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed in a mass ratio of 0.7 - 0.8: 0.4 - 0.5: 0.2 - 0.3.

[0027] Further, the mass ratio of dispersion liquid A to dispersion liquid B is 2:3.

[0028] Further, the preparation method of the hydroxylated boron nitride nanosheets includes the following steps:

[0029] According to the mass ratio of D-glucose, deionized water, and hexagonal boron nitride of 14.5 - 15.5: 25 - 35: 2.5 - 3.5, add D-glucose to deionized water and stir until completely dissolved, then add hexagonal boron nitride and ultrasonic treat for 20 - 30 min, then perform ball milling, the ball milling time is 11 - 13 h, the ball milling speed is 300 - 400 rpm, centrifuge at a speed of 10000 - 20000 rpm for 5 - 10 min, wash with deionized water 3 times (the mass of deionized water each time is 60% of the mass of the above deionized water), and finally vacuum dry at 55 - 65 °C for 24 h to obtain hydroxylated boron nitride nanosheets.

[0030] Further, step S2 is specifically:

[0031] Add the cemented carbide powder in step S1 into a mold, press and form it, then transfer it to a sintering furnace for spark plasma sintering, cool to room temperature after completion, then perform vacuum heat treatment, and then cool to room temperature to finally obtain an ultrafine cemented carbide cutting tool.

[0032] Further, the pressure for pressing and forming is 240 - 260 MPa.

[0033] Further, the process of spark plasma sintering is specifically as follows: under argon protection and a sintering pressure of 40 - 60 MPa, the temperature is raised to 1250 - 1300 °C at a rate of 100 °C / min and held for 8 - 12 min.

[0034] Further, the process of vacuum heat treatment is specifically as follows: the temperature is raised to 450 - 550 °C at a rate of 10 °C / min and held for 0.5 - 1.5 h, then the temperature is continuously raised to 600 - 700 °C and held for 0.5 - 1.5 h.

[0035] An ultra - fine cemented carbide cutting tool prepared by the above - mentioned preparation method.

[0036] The beneficial effects of the present invention:

[0037] (1) In the technical solution of the present invention, by ball - milling and sieving tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforcing composite powder, a cemented carbide powder is obtained; after ball - milling and sieving tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforcing composite powder, not only are the powders more uniformly mixed, but the obtained cemented carbide powder is also finer, which preferably improves the mechanical properties and thermal stability of the ultra - fine cemented carbide cutting tool; among them, the modified cobalt powder is prepared by spray - conversion method by mixing a vanadium source, a yttrium source and a cobalt source; the vanadium source is ammonium metavanadate, the yttrium source is yttrium acetate hydrate, and the cobalt source is cobalt acetate tetrahydrate. By using the spray - conversion method, the vanadium source, the yttrium source and the cobalt source are evenly distributed, and finally a modified cobalt powder containing vanadium and yttrium oxide is prepared. The presence of yttrium oxide can promote the formation of ultra - fine cobalt phase, thereby reducing dislocation movement, further improving the mechanical properties of the cemented carbide, and yttrium oxide can effectively inhibit the growth of tungsten carbide grains, enhancing the hardness, fracture toughness and corrosion resistance of the cemented carbide; the presence of vanadium also promotes the layer - by - layer growth of tungsten carbide on the plane, reduces its grain size, refines the tungsten carbide grains, and improves the flexural strength and fracture toughness of the cemented carbide, which can further improve the hardness and wear resistance of the ultra - fine cemented carbide cutting tool; therefore, by mixing the vanadium source, the yttrium source and the cobalt source, the obtained modified cobalt powder can preferably improve the overall performance of the ultra - fine cemented carbide cutting tool;

[0038] (2) In the technical solution of the present invention, an enhanced composite powder is prepared by electrostatic adsorption to combine nanoparticles with a reinforcing material; the nanoparticles are composed of a mixture of nano-aluminum oxide, nano-molybdenum oxide, and nano-lanthanum oxide; the mixture of nano-aluminum oxide, nano-molybdenum oxide, and nano-lanthanum oxide has a synergistic effect, which can effectively improve the hardness and fracture toughness of cemented carbide. Nano-aluminum oxide has advantages such as low density, high stiffness, high hardness, chemical inertness, and good high-temperature performance, and can better improve the fracture toughness and wear resistance of cemented carbide. Both nano-molybdenum oxide and nano-lanthanum oxide have high hardness, can enhance the wear resistance of cemented carbide, and have good chemical stability and oxidation resistance, and can form a dense oxidation protection layer in a high-temperature environment to prevent further oxidation and corrosion, improving the thermal stability and corrosion resistance of cemented carbide; the reinforcing material is composed of a mixture of graphene oxide and hydroxylated boron nitride nanosheets; graphene oxide and hydroxylated boron nitride nanosheets have a synergistic effect. Not only can they form an adsorption structure with nanoparticles through electrostatic adsorption to achieve their uniform dispersion, but also they can refine the tungsten carbide grains, further improving the hardness and fracture toughness of cemented carbide, and at the same time improving the wear resistance of cemented carbide. Combining the nanoparticles with the reinforcing material can better improve the mechanical properties and thermal stability of the ultra-fine cemented carbide cutting tool; after the cemented carbide powder is subjected to spark plasma sintering and then vacuum heat treatment, an ultra-fine cemented carbide cutting tool is finally obtained; spark plasma sintering can rapidly densify the cemented carbide powder, shorten the sintering time, effectively inhibit grain growth, form a finer and more uniform grain structure, and better improve the mechanical properties of cemented carbide. Through a staged vacuum heat treatment process, that is, vacuum heat treatment is carried out in a gradually heating manner, oxidation problems can be avoided, the bonding force of grain boundaries can be enhanced, the crack propagation resistance of cemented carbide can be improved, and the hardness and wear resistance of the ultra-fine cemented carbide cutting tool can be further enhanced;

[0039] (3) In the technical solution of the present invention, tungsten carbide powder, titanium carbide powder, modified cobalt powder, and enhanced composite powder are ball-milled and sieved to obtain a cemented carbide powder, and then subjected to spark plasma sintering and then vacuum heat treatment to finally obtain an ultra-fine cemented carbide cutting tool; the modified cobalt powder and the enhanced composite powder make the prepared ultra-fine cemented carbide cutting tool have good mechanical properties, wear resistance, and thermal stability, and extend the service life of the ultra-fine cemented carbide cutting tool, and the overall comprehensive performance is good. Specific embodiments

[0040] 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 of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0041] The specific parameters of the raw materials used in the present invention are as follows:

[0042] Tungsten carbide powder, particle size: 0.6 - 25 µm, provided by Dinghong (Shanghai) New Material Technology Co., Ltd.; titanium carbide powder, particle size: 1 - 2 µm, provided by Nangong Jiuxin New Material Technology Co., Ltd.; ammonium metavanadate, CAS No.: 7803 - 55 - 6, product number: A800974, provided by Shanghai Macklin Biochemical Co., Ltd.; yttrium acetate hydrate, active ingredient content: 99%, provided by Wuhan Huaxiang Kejie Biotechnology Co., Ltd.; cobalt acetate tetrahydrate, CAS No.: 6147 - 53 - 1, product number: C805229, provided by Shanghai Macklin Biochemical Co., Ltd.; graphene oxide, number: S25040, provided by Shanghai Yuanye Bio-Technology Co., Ltd.; hexagonal boron nitride, particle size: 1 - 2 µm, CAS No.: 10043 - 11 - 5, provided by Ningbo Luofei Nano Technology Co., Ltd.; nano-aluminum oxide, average particle size: 50 nm, provided by Yumu (Ningbo) New Material Co., Ltd.; nano-molybdenum oxide, particle size: 50 nm, provided by Hangzhou Hengge Nano Technology Co., Ltd.; nano-lanthanum oxide, average particle size: 50 nm, provided by Ningbo Luofei Nano Technology Co., Ltd.

[0043] Example 1

[0044] To prepare an ultra-fine cemented carbide cutting tool, the specific steps are as follows:

[0045] S1: According to the mass ratio of polyvinylpyrrolidone, absolute ethanol, tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder of 0.01:15:0.9:0.1:0.15:0.05, add polyvinylpyrrolidone and absolute ethanol into the reaction kettle, and stir at 50 °C at a speed of 400 rpm for 35 min. Then, under nitrogen protection, add tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder, and stir for 15 min. Then, perform ultrasonic dispersion for 25 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). Then, under nitrogen protection, perform ball milling at a speed of 80 r / min for 46 h, using WC-Co cemented carbide as the grinding balls, and the mass of the grinding balls is 2 times the total mass of tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder (i.e., the ball-to-powder ratio is 2:1). After ball milling, perform vacuum drying at 55 °C for 11 h, and screen through a 400-mesh sieve to obtain the cemented carbide powder;

[0046] Among them, the preparation method of the modified cobalt powder includes the following steps:

[0047] According to the mass ratio of ammonium metavanadate, yttrium acetate hydrate, cobalt acetate tetrahydrate and deionized water being 1:1:92:450, ammonium metavanadate, yttrium acetate hydrate and cobalt acetate tetrahydrate were added to deionized water, and stirred at 55 °C at a rotation speed of 200 rpm for 35 min to obtain a mixed solution. The mixed solution was spray-converted at a speed of 3 rpm, the inlet temperature of the spray conversion was 215 °C, and the outlet temperature was 125 °C to obtain a precursor powder. The precursor powder was calcined at 295 °C for 1 h to obtain an oxide powder. The oxide powder was reduced by hydrogen at 495 °C for 1 h, and the hydrogen flow rate was 1 m 3 / h, and finally modified cobalt powder was obtained;

[0048] The preparation method of the reinforced composite powder includes the following steps:

[0049] According to the mass ratio of the reinforcing material to deionized water being 3.5:800, the reinforcing material was added to deionized water and ultrasonically dispersed for 4 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion liquid A. According to the mass ratio of the nanoparticles to deionized water being 5.5:1000, the nanoparticles were added to deionized water, and then 1 mol / L hydrochloric acid solution was added to adjust the pH value to 3, and then ultrasonically treated for 2 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion liquid B. According to the mass ratio of dispersion liquid A to dispersion liquid B being 2:3, dispersion liquid B was added to dispersion liquid A and stirred for 1 h. Finally, it was freeze-dried at -50 °C for 48 h to obtain the reinforced composite powder. Among them, the reinforcing material was composed of graphene oxide and hydroxylated boron nitride nanosheets mixed according to the mass ratio of 0.9:0.7; the nanoparticles were composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed according to the mass ratio of 0.7:0.4:0.2;

[0050] The preparation method of the hydroxylated boron nitride nanosheets includes the following steps:

[0051] According to the mass ratio of D-glucose, deionized water and hexagonal boron nitride being 14.5:25:2.5, D-glucose was added to deionized water and stirred until completely dissolved, then hexagonal boron nitride was added, and ultrasonically treated for 20 min (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz), and then ball-milled. The ball-milling time was 11 h, the ball-milling rotation speed was 400 rpm, zirconia balls were used as the grinding spheres, and the mass of the grinding spheres was 8 times the mass of hexagonal boron nitride (i.e., the ball-to-material ratio was 8:1). Then it was centrifuged at a rotation speed of 10000 rpm for 10 min, washed 3 times with deionized water (the mass of deionized water each time was 60% of the mass of the above deionized water), and finally vacuum-dried at 55 °C for 24 h to obtain the hydroxylated boron nitride nanosheets;

[0052] S2: Add the cemented carbide powder in step S1 into a graphite mold with a diameter of 20 mm, and press it into shape under a pressure of 240 MPa. Then transfer it to a sintering furnace for spark plasma sintering. Under argon protection and a sintering pressure of 40 MPa, heat it up to 1250 °C at a rate of 100 °C / min, and hold for 8 min. After that, cool it to room temperature, and then conduct vacuum heat treatment (vacuum degree is 0.5 Pa). Heat it up to 450 °C at a rate of 10 °C / min and hold for 1.5 h. Continue to heat it up to 600 °C at a rate of 10 °C / min and hold for 1.5 h. Then cool it to room temperature, and finally obtain an ultrafine cemented carbide tool.

[0053] Example 2

[0054] The steps for preparing an ultrafine cemented carbide tool are as follows:

[0055] S1: According to the mass ratio of polyvinylpyrrolidone, absolute ethanol, tungsten carbide powder, titanium carbide powder, modified cobalt powder, and reinforcing composite powder being 0.02:20:1:0.15:0.2:0.1, add polyvinylpyrrolidone and absolute ethanol into a reaction kettle, and stir at 55 °C at a rotation speed of 500 rpm for 30 min. Then, under nitrogen protection, add tungsten carbide powder, titanium carbide powder, modified cobalt powder, and reinforcing composite powder, and stir for 20 min. Then conduct ultrasonic dispersion for 30 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). Then, under nitrogen protection, conduct ball milling at a rotation speed of 80 r / min for 48 h. Use WC-Co cemented carbide as the grinding spheres, and the mass of the grinding spheres is 2 times the total mass of tungsten carbide powder, titanium carbide powder, modified cobalt powder, and reinforcing composite powder (i.e., the ball-to-powder ratio is 2:1). After ball milling, conduct vacuum drying at 60 °C for 12 h, and sieve through a 450-mesh sieve to obtain the cemented carbide powder;

[0056] Among them, the preparation method of the modified cobalt powder includes the following steps:

[0057] According to the mass ratio of ammonium metavanadate, yttrium acetate hydrate, cobalt acetate tetrahydrate, and deionized water being 1.5:1.5:92.5:500, add ammonium metavanadate, yttrium acetate hydrate, and cobalt acetate tetrahydrate into deionized water, and stir at 60 °C at a rotation speed of 300 rpm for 30 min to obtain a mixed solution. Spray-convert the mixed solution at a speed of 5 rpm. The inlet temperature of the spray conversion is 220 °C, and the outlet temperature is 130 °C to obtain a precursor powder. Calcinate the precursor powder at 300 °C for 1.5 h to obtain an oxide powder. Reduce the oxide powder at 500 °C through hydrogen for 1.5 h, and the hydrogen flow rate is 1 m 3 / h, and finally obtain the modified cobalt powder;

[0058] The preparation method of the reinforced composite powder comprises the following steps:

[0059] According to the mass ratio of the reinforcing material to deionized water being 4:900, add the reinforcing material into deionized water and ultrasonically disperse for 4.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz) to obtain dispersion liquid A. According to the mass ratio of the nanoparticles to deionized water being 6:1100, add the nanoparticles into deionized water, then add 1 mol / L hydrochloric acid solution and adjust the pH value to 3.3, and then ultrasonically treat for 2.5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz) to obtain dispersion liquid B. According to the mass ratio of dispersion liquid A to dispersion liquid B being 2:3, add dispersion liquid B into dispersion liquid A and stir for 1.5 h. Finally, freeze-dry at -45 °C for 48 h to obtain the reinforced composite powder. Among them, the reinforcing material is composed of graphene oxide and hydroxylated boron nitride nanosheets mixed according to the mass ratio of 1:0.75; the nanoparticles are composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed according to the mass ratio of 0.75:0.45:0.25;

[0060] The preparation method of the hydroxylated boron nitride nanosheets comprises the following steps:

[0061] According to the mass ratio of D-glucose, deionized water and hexagonal boron nitride being 15:30:3, add D-glucose into deionized water and stir until completely dissolved, then add hexagonal boron nitride and ultrasonically treat for 25 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then carry out ball milling. The ball milling time is 12 h, the ball milling speed is 350 rpm, use zirconia balls as the grinding spheres, and the mass of the grinding spheres is 8 times the mass of hexagonal boron nitride (i.e., the ball-to-material ratio is 8:1). Then centrifuge at a speed of 15000 rpm for 8 min, wash with deionized water 3 times (the mass of deionized water each time is 60% of the mass of the above deionized water), and finally vacuum dry at 60 °C for 24 h to obtain the hydroxylated boron nitride nanosheets;

[0062] S2: Add the cemented carbide powder in step S1 into a graphite mold with a diameter of 20 mm, and press and form it. The pressure for pressing and forming is 250 MPa, then transfer it to a sintering furnace for spark plasma sintering. Under argon protection and a sintering pressure of 50 MPa, heat it to 1280 °C at a rate of 100 °C / min and keep it warm for 10 min. After completion, cool it to room temperature, and then carry out vacuum heat treatment (vacuum degree is 0.5 Pa). Heat it to 500 °C at a rate of 10 °C / min and keep it warm for 1 h, continue to heat it to 650 °C at a rate of 10 °C / min and keep it warm for 1 h, and then cool it to room temperature. Finally, obtain the ultra-fine cemented carbide cutting tool.

[0063] Example 3

[0064] To prepare an ultrafine cemented carbide tool, the specific steps are as follows:

[0065] S1: According to the mass ratio of polyvinylpyrrolidone, absolute ethanol, tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder being 0.03:25:1.1:0.2:0.25:0.15, add polyvinylpyrrolidone and absolute ethanol into the reaction kettle, and stir at 60 °C at a speed of 600 rpm for 25 min. Then, under nitrogen protection, add tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder, and stir for 25 min. Then perform ultrasonic dispersion for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz). Then, under nitrogen protection, perform ball milling at a speed of 80 r / min for 50 h, using WC-Co cemented carbide as the grinding spheres, and the mass of the grinding spheres is 2 times the total mass of tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder (i.e., the ball-powder ratio is 2:1). After the ball milling is completed, perform vacuum drying at 65 °C for 13 h, and sieve through a 500-mesh sieve to obtain the cemented carbide powder;

[0066] Among them, the preparation method of the modified cobalt powder includes the following steps:

[0067] According to the mass ratio of ammonium metavanadate, yttrium acetate hydrate, cobalt acetate tetrahydrate and deionized water being 2:2:93:550, add ammonium metavanadate, yttrium acetate hydrate and cobalt acetate tetrahydrate into deionized water, and stir at 65 °C at a speed of 400 rpm for 25 min to obtain a mixed solution. Spray-convert the mixed solution at a speed of 7 rpm, with the inlet temperature of the spray conversion being 225 °C and the outlet temperature being 135 °C to obtain the precursor powder. Calcinate the precursor powder at 305 °C for 2 h to obtain the oxide powder. Reduce the oxide powder with hydrogen at 505 °C for 2 h, and the hydrogen flow rate is 1 m 3 / h, and finally obtain the modified cobalt powder;

[0068] The preparation method of the reinforced composite powder includes the following steps:

[0069] According to the mass ratio of the reinforcing material to deionized water being 4.5:1000, the reinforcing material was added to deionized water and ultrasonically dispersed for 5 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion A. According to the mass ratio of the nanoparticles to deionized water being 6.5:1200, the nanoparticles were added to deionized water, then 1 mol / L hydrochloric acid solution was added and the pH value was adjusted to 3.5, and then ultrasonic treatment was carried out for 3 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion B. According to the mass ratio of dispersion A to dispersion B being 2:3, dispersion B was added to dispersion A and stirred for 2 h, and finally freeze-dried at -40 °C for 48 h to obtain the reinforced composite powder. Among them, the reinforcing material was composed of graphene oxide and hydroxylated boron nitride nanosheets mixed according to the mass ratio of 1.1:0.8; the nanoparticles were composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed according to the mass ratio of 0.8:0.5:0.3;

[0070] The preparation method of the hydroxylated boron nitride nanosheets includes the following steps:

[0071] According to the mass ratio of D-glucose, deionized water, and hexagonal boron nitride being 15.5:35:3.5, D-glucose was added to deionized water and stirred until completely dissolved, then hexagonal boron nitride was added, and ultrasonic treatment was carried out for 30 min (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz), then ball milling was carried out. The ball milling time was 13 h, the ball milling speed was 300 rpm, zirconia balls were used as the grinding balls, and the mass of the grinding balls was 8 times the mass of hexagonal boron nitride (i.e., the ball-to-material ratio was 8:1). Then centrifugation was carried out at a speed of 20000 rpm for 5 min, washed 3 times with deionized water (the mass of deionized water each time was 60% of the mass of the above deionized water), and finally vacuum dried at 65 °C for 24 h to obtain the hydroxylated boron nitride nanosheets;

[0072] S2: The cemented carbide powder in step S1 was added to a graphite mold with a diameter of 20 mm and pressed into shape. The pressure for pressing into shape was 260 MPa, and then it was transferred to a sintering furnace for spark plasma sintering. Under argon protection and a sintering pressure of 60 MPa, it was heated to 1300 °C at a rate of 100 °C / min and held for 12 min. After completion, it was cooled to room temperature, and then vacuum heat treatment (vacuum degree was 0.5 Pa) was carried out. It was heated to 550 °C at a rate of 10 °C / min and held for 0.5 h, and continued to be heated to 700 °C at a rate of 10 °C / min and held for 0.5 h, and then cooled to room temperature. Finally, an ultrafine cemented carbide cutting tool was obtained.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 3 is that when preparing the ultrafine cemented carbide tool, in step S1, the modified cobalt powder is prepared by mixing a vanadium source and a cobalt source through a spray conversion method, and the remaining steps and raw materials are the same as those in Example 3;

[0075] The preparation method of the modified cobalt powder includes the following steps:

[0076] According to the mass ratio of ammonium metavanadate, cobalt acetate tetrahydrate and deionized water being 2:93:550, add ammonium metavanadate and cobalt acetate tetrahydrate to deionized water, and stir at 65 °C at a speed of 400 rpm for 25 min to obtain a mixed solution. Spray-convert the mixed solution at a speed of 7 rpm. The inlet temperature of the spray conversion is 225 °C, and the outlet temperature is 135 °C to obtain a precursor powder. Calcinate the precursor powder at 305 °C for 2 h to obtain an oxide powder. Reduce the oxide powder with hydrogen at 505 °C for 2 h, and the hydrogen flow rate is 1 m 3 / h, and finally obtain the modified cobalt powder.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 3 is that when preparing the ultrafine cemented carbide tool, in step S1, the modified cobalt powder is prepared by mixing a yttrium source and a cobalt source through a spray conversion method, and the remaining steps and raw materials are the same as those in Example 3;

[0079] The preparation method of the modified cobalt powder includes the following steps:

[0080] According to the mass ratio of yttrium acetate hydrate, cobalt acetate tetrahydrate and deionized water being 2:93:550, add yttrium acetate hydrate and cobalt acetate tetrahydrate to deionized water, and stir at 65 °C at a speed of 400 rpm for 25 min to obtain a mixed solution. Spray-convert the mixed solution at a speed of 7 rpm. The inlet temperature of the spray conversion is 225 °C, and the outlet temperature is 135 °C to obtain a precursor powder. Calcinate the precursor powder at 305 °C for 2 h to obtain an oxide powder. Reduce the oxide powder with hydrogen at 505 °C for 2 h, and the hydrogen flow rate is 1 m 3 / h, and finally obtain the modified cobalt powder.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 3 is that when preparing the ultrafine cemented carbide tool, in step S1, the reinforcing material is replaced with graphene oxide in equal mass, and the remaining steps and raw materials are the same as those in Example 3;

[0083] The preparation method of the reinforced composite powder includes the following steps:

[0084] According to the mass ratio of graphene oxide to deionized water being 4.5:1000, graphene oxide was added to deionized water and ultrasonically dispersed for 5 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion A. According to the mass ratio of nanoparticles to deionized water being 6.5:1200, the nanoparticles were added to deionized water, then 1 mol / L hydrochloric acid solution was added and the pH value was adjusted to 3.5, and then ultrasonic treatment was carried out for 3 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion B. According to the mass ratio of dispersion A to dispersion B being 2:3, dispersion B was added to dispersion A and stirred for 2 h, and finally freeze-dried at -40 °C for 48 h to obtain the enhanced composite powder. Among them, the nanoparticles were composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed in a mass ratio of 0.8:0.5:0.3.

[0085] Comparative Example 4

[0086] The difference between this comparative example and Example 3 is that when preparing the ultra-fine cemented carbide tool, in step S1, the reinforcing material was replaced with hydroxylated boron nitride nanosheets in equal mass, and the remaining steps and raw materials were the same as those in Example 3;

[0087] The preparation method of the enhanced composite powder includes the following steps:

[0088] According to the mass ratio of hydroxylated boron nitride nanosheets to deionized water being 4.5:1000, the hydroxylated boron nitride nanosheets were added to deionized water and ultrasonically dispersed for 5 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion A. According to the mass ratio of nanoparticles to deionized water being 6.5:1200, the nanoparticles were added to deionized water, then 1 mol / L hydrochloric acid solution was added and the pH value was adjusted to 3.5, and then ultrasonic treatment was carried out for 3 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion B. According to the mass ratio of dispersion A to dispersion B being 2:3, dispersion B was added to dispersion A and stirred for 2 h, and finally freeze-dried at -40 °C for 48 h to obtain the enhanced composite powder. Among them, the nanoparticles were composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed in a mass ratio of 0.8:0.5:0.3.

[0089] Comparative Example 5

[0090] The difference between this comparative example and Example 3 is that when preparing the ultra-fine cemented carbide tool, in step S1, the nanoparticles were composed of nano-aluminum oxide and nano-molybdenum oxide mixed, and the remaining steps and raw materials were the same as those in Example 3;

[0091] The preparation method of the enhanced composite powder includes the following steps:

[0092] According to the mass ratio of the reinforcing material to deionized water being 4.5:1000, the reinforcing material was added to deionized water and ultrasonically dispersed for 5 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion A. According to the mass ratio of the nanoparticles to deionized water being 6.5:1200, the nanoparticles were added to deionized water, then 1 mol / L hydrochloric acid solution was added and the pH value was adjusted to 3.5, and then ultrasonic treatment was carried out for 3 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion B. According to the mass ratio of dispersion A to dispersion B being 2:3, dispersion B was added to dispersion A and stirred for 2 h, and finally freeze-dried at -40 °C for 48 h to obtain the reinforced composite powder. Among them, the reinforcing material was composed of graphene oxide and hydroxylated boron nitride nanosheets mixed in a mass ratio of 1.1:0.8; the nanoparticles were composed of nano-aluminum oxide and nano-molybdenum oxide mixed in a mass ratio of 0.8:0.8.

[0093] Comparative Example 6

[0094] The difference between this comparative example and Example 3 is that when preparing the ultra-fine cemented carbide tool, in step S1, the nanoparticles were composed of nano-aluminum oxide and nano-lanthanum oxide, and the remaining steps and raw materials were the same as those in Example 3;

[0095] The preparation method of the reinforced composite powder includes the following steps:

[0096] According to the mass ratio of the reinforcing material to deionized water being 4.5:1000, the reinforcing material was added to deionized water and ultrasonically dispersed for 5 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion A. According to the mass ratio of the nanoparticles to deionized water being 6.5:1200, the nanoparticles were added to deionized water, then 1 mol / L hydrochloric acid solution was added and the pH value was adjusted to 3.5, and then ultrasonic treatment was carried out for 3 h (ultrasonic power was 100 W, ultrasonic frequency was 40 kHz) to obtain dispersion B. According to the mass ratio of dispersion A to dispersion B being 2:3, dispersion B was added to dispersion A and stirred for 2 h, and finally freeze-dried at -40 °C for 48 h to obtain the reinforced composite powder. Among them, the reinforcing material was composed of graphene oxide and hydroxylated boron nitride nanosheets mixed in a mass ratio of 1.1:0.8; the nanoparticles were composed of nano-aluminum oxide and nano-lanthanum oxide mixed in a mass ratio of 0.8:0.8.

[0097] Comparative Example 7

[0098] The difference between this comparative example and Example 3 is that when preparing the ultra-fine cemented carbide tool, in step S1, the nanoparticles were composed of nano-molybdenum oxide and nano-lanthanum oxide, and the remaining steps and raw materials were the same as those in Example 3;

[0099] The preparation method of the reinforced composite powder comprises the following steps:

[0100] According to the mass ratio of the reinforcing material to deionized water being 4.5:1000, add the reinforcing material to deionized water and ultrasonically disperse for 5 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz) to obtain dispersion liquid A. According to the mass ratio of the nanoparticles to deionized water being 6.5:1200, add the nanoparticles to deionized water, then add 1 mol / L hydrochloric acid solution and adjust the pH value to 3.5, and then ultrasonically treat for 3 h (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz) to obtain dispersion liquid B. According to the mass ratio of dispersion liquid A to dispersion liquid B being 2:3, add dispersion liquid B to dispersion liquid A and stir for 2 h, and finally freeze-dry at -40 °C for 48 h to obtain the reinforced composite powder. Among them, the reinforcing material is composed of graphene oxide and hydroxylated boron nitride nanosheets mixed according to the mass ratio of 1.1:0.8; the nanoparticles are composed of molybdenum oxide nanoparticles and lanthanum oxide nanoparticles mixed according to the mass ratio of 0.8:0.8.

[0101] Comparative Example 8

[0102] The difference between this comparative example and Example 3 is that when preparing the ultra-fine cemented carbide tool, in step S2, the process of vacuum heat treatment is specifically: heat up to 550 °C at a rate of 10 °C / min, hold for 0.5 h, then cool to room temperature, and the remaining steps and raw materials are the same as those in Example 3;

[0103] S2: Add the cemented carbide powder in step S1 into a graphite mold with a diameter of 20 mm, press and mold it, the pressure for pressing and molding is 260 MPa, then transfer it to a sintering furnace for spark plasma sintering. Under argon protection and a sintering pressure of 60 MPa, heat up to 1300 °C at a rate of 100 °C / min, hold for 12 min, and after cooling to room temperature, perform vacuum heat treatment (vacuum degree is 0.5 Pa), heat up to 550 °C at a rate of 10 °C / min, hold for 0.5 h, then cool to room temperature, and finally obtain the ultra-fine cemented carbide tool.

[0104] The hardness, flexural strength, fracture toughness, and wear resistance of the ultrafine cemented carbide tools prepared in Examples 1-3 and Comparative Examples 1-8 were tested. Hardness test: Vickers hardness test was carried out according to the detection standard of GB / T 4340.1-2009. Flexural strength test: Flexural strength test was carried out according to the detection standard of GB / T 3851-2015. Fracture toughness test: Fracture toughness test was carried out according to the detection standard of GB / T23806-2009. Wear resistance test: The ball-on-disk friction and wear test was used for the ultrafine cemented carbide tools prepared in Examples 1-3 and Comparative Examples 1-8. The loading force was 100 N, the rotation speed was 100 r / min, and the time was 45 min. The wear amount was recorded. The larger the wear amount, the worse the wear resistance. The test results are shown in Table 1 below:

[0105] Table 1 Performance parameters of the ultrafine cemented carbide tools prepared in Examples 1-3 and Comparative Examples 1-8

[0106]

[0107] It can be seen from the data in Table 1 above that by comparing Comparative Examples 1-2 and Example 3, in step S1, the modified cobalt powder used was prepared by mixing a vanadium source and a cobalt source through a spray conversion method, or the modified cobalt powder was prepared by mixing a yttrium source and a cobalt source through a spray conversion method. Finally, for the prepared ultrafine cemented carbide tool, its test results were worse than those of Example 3. This shows that by mixing the vanadium source, yttrium source, and cobalt source through a spray conversion method, the vanadium source, yttrium source, and cobalt source can be evenly distributed, and the modified cobalt powder containing vanadium and yttrium oxide can be prepared, which can effectively inhibit the growth of tungsten carbide grains, better enhance the hardness, flexural strength, and fracture toughness of the cemented carbide, and further improve the wear resistance and mechanical properties of the ultrafine cemented carbide tool;

[0108] It can be seen from the comparison between Comparative Examples 3-7 and Example 3 that in step S1, when the reinforcing material was replaced with graphene oxide or hydroxylated boron nitride nanosheets in equal mass, or the nanoparticles were composed of a mixture of nano-aluminum oxide and nano-molybdenum oxide, or the nanoparticles were composed of a mixture of nano-aluminum oxide and nano-lanthanum oxide, or the nanoparticles were composed of a mixture of nano-molybdenum oxide and nano-lanthanum oxide, and finally the ultrafine cemented carbide tool was prepared, its test results were worse than those of Example 3. This shows that the reinforcing material composed of a mixture of graphene oxide and hydroxylated boron nitride nanosheets has a synergistic effect, which can not only combine well with the nanoparticles, but also effectively improve the mechanical properties and wear resistance of the ultrafine cemented carbide tool; The nanoparticles composed of a mixture of nano-aluminum oxide, nano-molybdenum oxide, and nano-lanthanum oxide have a synergistic effect, which can better improve the hardness, flexural strength, and fracture toughness of the ultrafine cemented carbide tool, and further improve its wear resistance and thermal stability;

[0109] It can be seen from the comparison between Comparative Example 8 and Example 3 that in step S2, the process of vacuum heat treatment is specifically as follows: heating to 550°C at a rate of 10°C / min, holding for 0.5 h, then cooling to room temperature, and finally preparing an ultrafine cemented carbide tool. The test results are worse than those of Example 3, indicating that after spark plasma sintering the cemented carbide powder and then performing a staged vacuum heat treatment process, that is, performing vacuum heat treatment in a stepwise heating manner, the growth of tungsten carbide grains can be further inhibited, the bonding force of grain boundaries can be enhanced, the crack propagation resistance of the cemented carbide can be enhanced, and the hardness, bending strength, fracture toughness, and wear resistance of the ultrafine cemented carbide tool can be further improved.

[0110] As can be seen from Table 1 above, compared with the ultrafine cemented carbide tools prepared in Comparative Examples 1-8, the ultrafine cemented carbide tools prepared in Examples 1-3 are obtained by ball milling, sieving tungsten carbide powder, titanium carbide powder, modified cobalt powder, and reinforcing composite powder to obtain a cemented carbide powder body, then performing spark plasma sintering, and then performing vacuum heat treatment, and finally obtaining an ultrafine cemented carbide tool, meeting the requirements of test performance. However, the ultrafine cemented carbide tools prepared in Comparative Examples 1-8 do not meet the performance requirements standards, indicating that the ultrafine cemented carbide tools prepared by the present invention not only have good mechanical properties, thermal stability, and wear resistance, but also extend their service life, and the overall comprehensive performance is good.

[0111] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means 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 can be combined in a suitable manner in any one or more embodiments or examples.

[0112] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined by the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A preparation method of an ultra-fine cemented carbide cutting tool, characterized in that, It includes the following steps: S1: Ball-mill and screen tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder to obtain cemented carbide powder; S2: After subjecting the cemented carbide powder in step S1 to spark plasma sintering and then vacuum heat treatment, an ultrafine cemented carbide cutting tool is obtained; Among them, the modified cobalt powder is prepared by mixing a vanadium source, a yttrium source and a cobalt source through a spray conversion method; The reinforced composite powder is prepared by electrostatic adsorption to combine nanoparticles with a reinforcing material; The reinforcing material is composed of graphene oxide and hydroxylated boron nitride nanosheets mixed in a mass ratio of 0.9 - 1.1:0.7 - 0.8; The nanoparticles are composed of nano-aluminum oxide, nano-molybdenum oxide and nano-lanthanum oxide mixed in a mass ratio of 0.7 - 0.8:0.4 - 0.5:0.2 - 0.3; The process of the vacuum heat treatment is specifically as follows: Heat up to 450 - 550 °C at a rate of 10 °C / min and hold for 0.5 - 1.5 h, then continue to heat up to 600 - 700 °C and hold for 0.5 - 1.5 h.

2. The preparation method of an ultra-fine cemented carbide cutting tool according to claim 1, wherein Step S1 is specifically as follows: Add polyvinylpyrrolidone and absolute ethanol into a reaction kettle, stir at 50 - 60 °C for 25 - 35 min, then add tungsten carbide powder, titanium carbide powder, modified cobalt powder and reinforced composite powder under nitrogen protection and stir for 15 - 25 min, then perform ultrasonic dispersion for 25 - 35 min, then perform ball-milling for 46 - 50 h under nitrogen protection. After the ball-milling is completed, vacuum dry at 55 - 65 °C and screen through a 400 - 500 mesh sieve to obtain cemented carbide powder.

3. The preparation method of an ultra-fine cemented carbide cutting tool according to claim 2, characterized in that, The preparation method of the modified cobalt powder includes the following steps: Add a vanadium source, a yttrium source and a cobalt source into deionized water, stir at 55 - 65 °C for 25 - 35 min to obtain a mixed solution, perform spray conversion on the mixed solution to obtain a precursor powder, calcine the precursor powder at 295 - 305 °C for 1 - 2 h to obtain an oxide powder, and reduce the oxide powder at 495 - 505 °C by hydrogen for 1 - 2 h to finally obtain the modified cobalt powder.

4. The preparation method of an ultra-fine cemented carbide cutting tool according to claim 3, characterized in that, The mass ratio of the vanadium source, the yttrium source, the cobalt source and deionized water is 1 - 2:1 - 2:92 - 93:450 - 550; the vanadium source is ammonium metavanadate; the yttrium source is yttrium acetate hydrate; the cobalt source is cobalt acetate tetrahydrate.

5. The preparation method of an ultra-fine cemented carbide cutting tool according to claim 2, characterized in that, The preparation method of the reinforced composite powder includes the following steps: Add the reinforcing material into deionized water and perform ultrasonic dispersion for 4 - 5 h to obtain dispersion liquid A; add the nanoparticles into deionized water, then add a hydrochloric acid solution to adjust the pH value to 3 - 3.5, and then perform ultrasonic treatment for 2 - 3 h to obtain dispersion liquid B; add dispersion liquid B into dispersion liquid A and stir for 1 - 2 h, and finally freeze-dry at -50 - -40 °C to obtain the reinforced composite powder.

6. The preparation method of an ultra-fine cemented carbide cutting tool according to claim 1, characterized in that, Step S2 is specifically as follows: Add the cemented carbide powder in step S1 into a mold, press and form it, then transfer it to a sintering furnace for spark plasma sintering. After completion, cool to room temperature, then perform vacuum heat treatment, and then cool to room temperature to finally obtain an ultrafine cemented carbide cutting tool.

7. An ultrafine cemented carbide cutting tool prepared by the preparation method according to any one of claims 1-6.

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