An ultra-fine cemented carbide cutting tool material for high-temperature material processing and its preparation method

Abstract

The present invention belongs to the technical field of cemented carbide manufacturing, and particularly relates to an ultra-fine cemented carbide cutting tool material for high-temperature material processing and a preparation method thereof. By selecting a composite hard phase formed by modified tungsten carbide and lanthanum-modified tungsten carbide, and introducing graphene-nickel composite powder into the binder phase high-entropy alloy to form a composite material, the present invention prepares an ultra-fine cemented carbide cutting tool material for high-temperature material processing, improves the Vickers hardness of the material, increases the fracture toughness, and obtains good flexural strength.

Description

Technical Field

[0001] The invention belongs to the technical field of cemented carbide manufacturing, and specifically relates to an ultrafine cemented carbide tool material for high-temperature material processing and a preparation method thereof. Background Art

[0002] In the entire cutting process system, machine tools, cutting tools, fixtures and workpieces are the main components, among which cutting tools are the most active factors. High-performance cutting tools can effectively improve the performance of the cutting system, thereby improving the efficiency of cutting processing, and at the same time can also obtain good economic benefits; with the continuous development of related technologies, higher requirements are put forward for traditional cutting tool materials. In order to meet this demand, the market needs to provide more cutting tool materials with better cutting performance. Cemented carbide is composed of refractory metal carbides such as tungsten carbide, titanium carbide, molybdenum carbide and iron group metals such as iron, cobalt, nickel, etc. Compared with high-speed steel cutting tools, cemented carbide is dozens of times more durable, so it has become an ideal material for manufacturing cutting tools.

[0003] The Chinese patent (publication number CN118875287B) discloses an ultrafine cemented carbide tool with a high entropy alloy binder phase and its preparation method. The high entropy alloy powder is prepared by high temperature melting-vacuum gas atomization method. The high entropy alloy powder is used as a binder phase, and the optimized sintering process is used to promote the refinement of WC grains and the preferred orientation of the crystal plane during WC recrystallization during sintering, thereby improving the performance of cemented carbide. The invention has low production cost and is suitable for industrial mass production. However, when ultrafine cemented carbide tool materials are used in high temperature material processing in the prior art, there are still problems such as low Vickers hardness, low fracture toughness, and insufficient bending strength, which seriously affect its actual use.

[0004] Therefore, how to modify the hard phase tungsten carbide of the tool material and introduce a functionalized bonding phase to prepare ultrafine cemented carbide tool materials for high-temperature material processing, improve the Vickers hardness of the material, increase the fracture toughness, and obtain good bending strength has become a direction that needs to be focused on. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an ultrafine cemented carbide tool material for high temperature material processing and a preparation method thereof, aiming to solve the problems of low Vickers hardness, low fracture toughness, and insufficient bending strength when ultrafine cemented carbide tool materials are used in high temperature material processing in the prior art.

[0006] The present invention prepares an ultrafine cemented carbide tool material for high-temperature material processing by selecting a composite hard phase formed by modified tungsten carbide and lanthanum-modified tungsten carbide, and introducing graphene-nickel composite powder into a binder high-entropy alloy to form a composite material, improving the Vickers hardness of the material, increasing the fracture toughness, and obtaining good flexural strength.

[0007] An ultrafine cemented carbide tool material for high-temperature material processing, in parts by weight, comprises the following components: 46-50 parts of modified tungsten carbide, 42-46 parts of lanthanum-modified tungsten carbide, 4-12 parts of high-entropy alloy, and 0.2-0.6 part of carbon powder.

[0008] The preparation method of the modified tungsten carbide comprises: in parts by weight, mixing 90-95 parts of tungsten carbide, 4-8 parts of tungsten powder, and 1-2 parts of graphene oxide by ball milling to obtain a mixed powder; subjecting the mixed powder to hot press sintering to obtain a blank, and pulverizing to obtain the modified tungsten carbide.

[0009] As a preferred technical solution of the present invention, the conditions of the ball milling include: the rotation speed is 100-120 rpm, the time is 12-16 h, and after the ball milling is completed, it is vacuum sieved through a 100-200 mesh sieve.

[0010] As a preferred technical solution of the present invention, the conditions of the hot press sintering include: filling the mixed powder in a mold, then putting it into a hot press sintering furnace, under the condition of a vacuum degree of 0.6-0.8 Pa, first heating to 900-1000 °C and holding for 10-20 min, applying a pressure of 110-120 MPa, then heating to 1700-1800 °C and holding for 30-40 min, cooling to room temperature, and releasing the pressure.

[0011] The graphene introduced by the modified tungsten carbide has extremely high strength and rigidity. It can be effectively dispersed in the tungsten carbide matrix, enhancing the overall hardness of the material by preventing crack propagation. At the same time, graphene can also transfer loads and disperse local stresses, delaying material failure and significantly increasing the hardness of the cemented carbide tool material.

[0012] As a preferred technical solution of the present invention, the preparation method of the lanthanum-modified tungsten carbide comprises: in parts by weight, stirring and mixing 92-98 parts of tungsten carbide and 1-3 parts of paraffin wax, then adding 2-4 parts of lanthanum powder, 1.2-1.8 parts of boron nitride quantum dots, and 40-50 parts of absolute ethanol for surface modification treatment to obtain the lanthanum-modified tungsten carbide.

[0013] As a preferred technical solution of the present invention, the conditions of the surface modification treatment include: placing it in a planetary ball mill and grinding at a speed of 280-300 r / min for 8-10 h, then vacuum drying at 70-80 °C for 3-5 h, and then holding at 190-200 °C for 12-14 h to remove the paraffin wax, and cooling to room temperature.

[0014] As a preferred technical solution of the present invention, the preparation method of the boron nitride quantum dots includes: taking 2-6 parts by weight of boric acid and 200-300 parts of deionized water, mixing and stirring them, and then adding 0.6-0.8 parts of melamine for heat treatment to obtain boron nitride quantum dots.

[0015] As a preferred technical solution of the present invention, the conditions of the heat treatment include: first stirring for 30-40 min, then heating up to 200-210 °C and reacting for 14-16 h, filtering, and freeze-drying.

[0016] The lanthanum introduced by lanthanum-modified tungsten carbide can form a protective film on the surface of tungsten carbide particles, indirectly improving the fracture toughness by changing the surface stress state. The boron nitride quantum dots can enhance the interfacial bonding force between particles, reduce the possibility of crack propagation, and thus improve the overall fracture toughness of the cemented carbide tool material.

[0017] As a preferred technical solution of the present invention, the high-entropy alloy is a high-entropy alloy composite material; the preparation method of the high-entropy alloy composite material includes: taking 35-40 parts by weight of cobalt powder, 20-25 parts of erbium powder, 25-30 parts of chromium powder, 5-10 parts of tungsten powder, and 5-10 parts of ruthenium powder, mixing them for melting and impurity removal, and then obtaining high-entropy alloy powder by vacuum gas atomization granulation; mixing 90-100 parts of the high-entropy alloy powder and 6-10 parts of graphene-nickel composite powder for mixing treatment to obtain a high-entropy alloy composite material.

[0018] As a preferred technical solution of the present invention, the conditions of the mixing treatment include: adding 100-120 parts of absolute ethanol and stirring for 1-3 h, and then vacuum drying at 60-70 °C for 8-10 h.

[0019] As a preferred technical solution of the present invention, the preparation method of the graphene-nickel composite powder includes: taking 10-20 parts by weight of graphene oxide, dispersing it in 80-100 parts of deionized water, adding 10-20 parts of nickel sulfate solution with a molar concentration of 1 mol / L and 2-6 parts of hydrazine hydrate for stirring reaction to obtain graphene-nickel composite powder.

[0020] As a preferred technical solution of the present invention, the conditions of the stirring reaction include: controlling the pH to be 12.4-12.8, stirring at a speed of 80-100 rpm at 80-90 °C for 60-80 min, filtering, washing the precipitate with water, and vacuum drying.

[0021] In the second aspect of the present invention, there is provided a preparation method of the ultra-fine cemented carbide tool material for high-temperature material processing as described in the first aspect;

[0022] It includes the following steps:

[0023] Step S1: Mix 46 - 50 parts by weight of modified tungsten carbide, 42 - 46 parts of lanthanum - modified tungsten carbide, 4 - 12 parts of high - entropy alloy, and 0.2 - 0.6 parts of carbon powder evenly. Then add the molding agent paraffin and conduct ball - milling, followed by spray - drying to obtain a green body.

[0024] Step S2: Place the green body in a vacuum environment, heat it to a temperature of 600 - 700 °C to remove the molding agent, then raise the temperature to 1480 - 1500 °C and sinter for 100 - 120 min, and cool to room temperature to obtain an ultra - fine cemented carbide tool material for high - temperature material processing.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The graphene introduced by the modified tungsten carbide in the present invention has a large specific surface area and excellent electron mobility. It can effectively adsorb boron nitride quantum dots in the lanthanum - modified tungsten carbide. At the same time, the defects on the surface of graphene provide high - activity sites for binding. Partial empty orbitals of lanthanum elements hybridize with the π - electron cloud of graphene to form covalent bonds, and boron nitride quantum dots can enhance the interfacial bonding strength. The combined effect improves the Vickers hardness and fracture toughness of the ultra - fine cemented carbide tool material, and increases the flexural strength, making it better applied to high - temperature material processing.

[0027] (2) The graphene introduced by the modified tungsten carbide in the present invention has extremely high strength and rigidity. It can be effectively dispersed in the tungsten carbide matrix, enhance the overall hardness of the material by preventing crack propagation. At the same time, graphene can also transfer loads and disperse local stresses, delaying material failure and significantly increasing the hardness of the cemented carbide tool material.

[0028] (3) Lanthanum introduced by the lanthanum - modified tungsten carbide in the present invention can form a protective film on the surface of tungsten carbide particles, indirectly improving the fracture toughness by changing the surface stress state. Boron nitride quantum dots can enhance the interfacial bonding force between particles, reducing the possibility of crack propagation, and thus improving the overall fracture toughness of the cemented carbide tool material.

[0029] (4) The binder phase of the present invention uses a high - entropy alloy composite material. By introducing graphene - nickel composite powder, the grain growth of the cemented carbide tool material can be inhibited, forming a finer and more uniform grain structure. The refined microstructure can effectively block the crack propagation path, and thus improve the flexural strength of the material. Specific Embodiments

[0030] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0031] The sources of some components in the examples and comparative examples are as follows:

[0032] Tungsten carbide, part number T111338, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0033] Carbon powder, part number C109965, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0034] Tungsten powder, part number T128183, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0035] Graphene oxide, model UG-SGraphene-01, purchased from Suzhou Youzirui Nano Materials Co., Ltd.;

[0036] Paraffin wax, CAS number 8012-95-1, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0037] Lanthanum powder, part number L812353, purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0038] Absolute ethanol, CAS number 64-17-5, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0039] Cobalt powder, part number C299285, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0040] Erbium powder, part number E112796, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0041] Chromium powder, part number C141222, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0042] Ruthenium powder, part number R105896, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0043] Nickel sulfate, CAS number 10101-97-0, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0044] Hydrazine hydrate, CAS number 7803-57-8, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0045] Example 1

[0046] This example provides a preparation method for an ultra-fine cemented carbide tool material for high-temperature material processing, including the following steps:

[0047] Step S1: In terms of parts by weight, 50 parts of modified tungsten carbide, 46 parts of lanthanum-modified tungsten carbide, 12 parts of high-entropy alloy composite material and 0.6 part of carbon powder are mixed evenly, and then 20 parts of molding agent paraffin wax are added for ball milling and spray drying to obtain a green body;

[0048] Step S2: Place the green body in a vacuum environment, heat it to 700 °C to remove the molding agent, then raise the temperature to 1500 °C and sinter for 100 min, and cool to room temperature to obtain an ultrafine cemented carbide tool material for high-temperature material processing.

[0049] Preparation of the modified tungsten carbide: By weight, mix 95 parts of tungsten carbide, 8 parts of tungsten powder, and 2 parts of graphene oxide, perform ball milling at a rotation speed of 120 rpm for 12 h. After the ball milling is completed, sieve through a 200-mesh sieve under vacuum to obtain a mixed powder; perform hot pressing sintering on the mixed powder. Fill the mixed powder into a mold, then place it in a hot pressing sintering furnace. Under the condition of a vacuum degree of 0.8 Pa, first raise the temperature to 1000 °C and hold for 10 min, apply a pressure of 120 MPa, then raise the temperature to 1800 °C and hold for 30 min, cool to room temperature, relieve the pressure, obtain a blank, and crush it to obtain modified tungsten carbide.

[0050] Preparation of the lanthanum-modified tungsten carbide: (1) By weight, mix 6 parts of boric acid and 300 parts of deionized water, stir, then add 0.8 part of melamine for heat treatment. First stir for 40 min, then raise the temperature to 210 °C and react for 14 h, filter, and freeze-dry to obtain boron nitride quantum dots. (2) By weight, mix 98 parts of tungsten carbide and 3 parts of paraffin wax, stir and mix, then add 4 parts of lanthanum powder, 1.8 parts of boron nitride quantum dots, and 50 parts of absolute ethanol for surface modification treatment. Place it in a planetary ball mill and grind at a speed of 300 r / min for 8 h, then vacuum dry at 80 °C for 3 h, and then hold at 200 °C for 12 h to remove the paraffin wax, and cool to room temperature to obtain lanthanum-modified tungsten carbide.

[0051] Preparation of the high-entropy alloy powder: By weight, mix 40 parts of cobalt powder, 25 parts of erbium powder, 25 parts of chromium powder, 5 parts of tungsten powder, and 5 parts of ruthenium powder for melting and impurity removal, and then obtain the high-entropy alloy powder through vacuum gas atomization granulation;

[0052] Preparation of the high-entropy alloy composite material: (1) By weight, disperse 20 parts of graphene oxide in 100 parts of deionized water, add 20 parts of nickel sulfate solution with a molar concentration of 1 mol / L and 6 parts of hydrazine hydrate for stirring reaction, control the pH to 12.8, and stir at a speed of 100 rpm at 90 °C for 60 min, filter, wash the precipitate with water, and vacuum dry to obtain a graphene-nickel composite powder; (2) By weight, mix 100 parts of the high-entropy alloy powder and 10 parts of the graphene-nickel composite powder, add 120 parts of absolute ethanol and stir for 3 h, then vacuum dry at 70 °C for 8 h to obtain the high-entropy alloy composite material.

[0053] Example 2

[0054] This embodiment provides a preparation method for an ultra-fine cemented carbide tool material for high-temperature material processing, comprising the following steps:

[0055] Step S1: By weight, 46 parts of modified tungsten carbide, 42 parts of lanthanum-modified tungsten carbide, 4 parts of high-entropy alloy composite material, and 0.2 part of carbon powder are mixed evenly, and then 10 parts of molding agent paraffin are added for ball milling and spray drying to obtain a green body.

[0056] Step S2: The green body is placed in a vacuum environment, heated to 600 °C to remove the molding agent, then heated to 1480 °C and sintered for 120 min, and cooled to room temperature to obtain an ultra-fine cemented carbide tool material for high-temperature material processing.

[0057] Preparation of the modified tungsten carbide: By weight, 90 parts of tungsten carbide, 4 parts of tungsten powder, and 1 part of graphene oxide are mixed and ball milled at a rotation speed of 100 rpm for 16 h. After the ball milling, it is vacuum sieved through a 100-mesh sieve to obtain a mixed powder; the mixed powder is subjected to hot pressing sintering. The mixed powder is filled in a mold, then placed in a hot pressing sintering furnace. Under the condition of a vacuum degree of 0.6 Pa, it is first heated to 900 °C and held for 20 min, a pressure of 110 MPa is applied, then heated to 1700 °C and held for 40 min, cooled to room temperature, the pressure is released, a blank is obtained, and it is crushed to obtain modified tungsten carbide.

[0058] Preparation of the lanthanum-modified tungsten carbide: (1) By weight, 2 parts of boric acid and 200 parts of deionized water are mixed and stirred, and then 0.6 part of melamine is added for heat treatment. First, it is stirred for 30 min, then heated to 200 °C and reacted for 16 h, filtered, and freeze-dried to obtain boron nitride quantum dots. (2) By weight, 92 parts of tungsten carbide and 1 part of paraffin are stirred and mixed, then 2 parts of lanthanum powder, 1.2 parts of boron nitride quantum dots, and 40 parts of absolute ethanol are added for surface modification treatment, placed in a planetary ball mill and ground at a speed of 280 r / min for 10 h, then vacuum dried at 70 °C for 5 h, and then held at 190 °C for 14 h to remove the paraffin, cooled to room temperature, to obtain lanthanum-modified tungsten carbide.

[0059] Preparation of the high-entropy alloy powder: By weight, 35 parts of cobalt powder, 20 parts of erbium powder, 25 parts of chromium powder, 10 parts of tungsten powder, and 10 parts of ruthenium powder are mixed for melting and impurity removal, and then high-entropy alloy powder is obtained by vacuum gas atomization granulation.

[0060] Preparation of high-entropy alloy composite material: (1) By weight, disperse 10 parts of graphene oxide in 80 parts of deionized water, add 10 parts of nickel sulfate solution with a molar concentration of 1 mol / L and 2 parts of hydrazine hydrate, and stir and react. Control the pH to 12.4, and stir at a speed of 80 rpm for 80 min at 80 °C. Filter, wash the precipitate with water, and dry it in vacuum to obtain graphene-nickel composite powder; (2) By weight, mix 90 parts of the high-entropy alloy powder and 6 parts of the graphene-nickel composite powder, add 10 parts of absolute ethanol and stir for 3 h, and then dry it in vacuum at 60 °C for 10 h to obtain the high-entropy alloy composite material.

[0061] Example 3

[0062] This example provides a preparation method of an ultra-fine cemented carbide cutting tool material for high-temperature material processing, including the following steps:

[0063] Step S1: By weight, mix 48 parts of modified tungsten carbide, 44 parts of lanthanum-modified tungsten carbide, 8 parts of high-entropy alloy composite material and 0.4 part of carbon powder evenly, then add 15 parts of molding agent paraffin and ball mill, and spray dry to obtain a green body;

[0064] Step S2: Place the green body in a vacuum environment, heat it to 650 °C to remove the molding agent, then raise the temperature to 1490 °C and sinter for 110 min, cool to room temperature to obtain an ultra-fine cemented carbide cutting tool material for high-temperature material processing.

[0065] Preparation of the modified tungsten carbide: By weight, mix 92 parts of tungsten carbide, 6 parts of tungsten powder, and 2 parts of graphene oxide and ball mill, with a rotation speed of 110 rpm and a time of 14 h. After ball milling, sieve through a 120-mesh sieve in vacuum to obtain a mixed powder; perform hot pressing sintering on the mixed powder. Fill the mixed powder in a mold, then put it into a hot pressing sintering furnace. Under the condition of a vacuum degree of 0.7 Pa, first raise the temperature to 950 °C and keep it warm for 15 min, apply a pressure of 115 MPa, then raise the temperature to 1750 °C and keep it warm for 35 min, cool to room temperature, relieve the pressure, obtain a blank, and crush it to obtain modified tungsten carbide.

[0066] Preparation of lanthanum-modified tungsten carbide: (1) By weight, 4 parts of boric acid and 250 parts of deionized water are mixed and stirred, and then 0.7 part of melamine is added for heat treatment. First, stir for 35 min, then heat up to 205 °C and react for 15 h, filter, and freeze-dry to obtain boron nitride quantum dots. (2) By weight, 94 parts of tungsten carbide and 2 parts of paraffin are stirred and mixed, and then 3 parts of lanthanum powder, 1.4 parts of boron nitride quantum dots, and 45 parts of absolute ethanol are added for surface modification treatment. Place it in a planetary ball mill and grind at a speed of 290 r / min for 9 h, then vacuum dry at 75 °C for 4 h, and then keep warm at 195 °C for 13 h to remove paraffin, and cool to room temperature to obtain lanthanum-modified tungsten carbide.

[0067] Preparation of high-entropy alloy powder: By weight, 38 parts of cobalt powder, 24 parts of erbium powder, 26 parts of chromium powder, 6 parts of tungsten powder, and 6 parts of ruthenium powder are mixed for melting and impurity removal, and then high-entropy alloy powder is obtained by vacuum gas atomization granulation;

[0068] Preparation of high-entropy alloy composite material: (1) By weight, 15 parts of graphene oxide are dispersed in 90 parts of deionized water, 15 parts of nickel sulfate solution with a molar concentration of 1 mol / L and 4 parts of hydrazine hydrate are added for stirring reaction, control the pH to 12.6, and stir at a speed of 90 rpm at 85 °C for 70 min, filter, wash the precipitate with water, and vacuum dry to obtain graphene-nickel composite powder; (2) By weight, 95 parts of the high-entropy alloy powder and 8 parts of the graphene-nickel composite powder are mixed and treated, 110 parts of absolute ethanol are added and stirred for 2 h, and then vacuum dried at 65 °C for 9 h to obtain high-entropy alloy composite material.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that commercially available tungsten carbide (product number T111338) is used to replace the modified tungsten carbide.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that commercially available tungsten carbide (product number T111338) is used to replace the lanthanum-modified tungsten carbide.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 1 is that high-entropy alloy powder is used to replace the high-entropy alloy composite material.

[0075] Comparative Example 4

[0076] The difference between this comparative example and Example 1 is that commercially available tungsten carbide (product number T111338) is used to replace the modified tungsten carbide, and high-entropy alloy powder is used to replace the high-entropy alloy composite material.

[0077] Comparative Example 5

[0078] The difference between this comparative example and Example 1 is that commercially available tungsten carbide (product number T111338) is used to replace lanthanum-modified tungsten carbide, and high-entropy alloy powder is used to replace the high-entropy alloy composite material.

[0079] The properties of the cemented carbide tool materials provided in the above examples and comparative examples were tested, and the test methods are as follows:

[0080] (1) Vickers hardness test: The test was carried out according to the requirements of "GB / T 7997-2014 Cemented Carbides - Vickers Hardness Test Method".

[0081] (2) Fracture toughness test: The test was carried out according to the requirements of "GB / T 33819-2017 Cemented Carbides - Barcol Toughness Test".

[0082] (3) Flexural strength test: The test was carried out according to the requirements of "GB / T 232-2024 Metallic Materials - Bend Test Method".

[0083] The above performance test data are shown in Table 1.

[0084] Table 1 Performance Test Results

[0085] Vickers hardness (HV20) <![CDATA[Fracture toughness (MPa·m 1 / 2 ).]]> Flexural strength (MPa) Example 1 2674 17.2 5386 Example 2 2659 16.5 5347 Example 3 2667 16.8 5362 Comparative Example 1 2286 13.1 4975 Comparative Example 2 2301 13.8 4993 Comparative Example 3 2293 13.5 4987 Comparative Example 4 1896 11.3 4659 Comparative Example 5 1905 11.6 4665

[0086] As can be seen from the above, in the present invention, by selecting a composite hard phase formed by modified tungsten carbide and lanthanum-modified tungsten carbide, and introducing a graphene-nickel composite powder into the binder phase high-entropy alloy to form a composite material, an ultrafine cemented carbide tool material for high-temperature material processing (Examples 1 to 3) is prepared, whose Vickers hardness (HV20) is 2659 to 2674, the fracture toughness is 16.5 to 17.2 MPa·m 1 / 2 , and the flexural strength is 5347 to 5386 MPa.

[0087] Compared with Example 1, when using commercially available tungsten carbide (product number T111338) to replace the modified tungsten carbide, the Vickers hardness decreases, the fracture toughness reduces, and the flexural strength becomes smaller (Comparative Example 1); compared with Example 1, when using commercially available tungsten carbide (product number T111338) to replace the lanthanum-modified tungsten carbide, the Vickers hardness decreases, the fracture toughness reduces, and the flexural strength becomes smaller (Comparative Example 2); compared with Example 1, when using high-entropy alloy powder to replace the high-entropy alloy composite material, the Vickers hardness decreases, the fracture toughness reduces, and the flexural strength becomes smaller (Comparative Example 3); compared with Example 1, when using commercially available tungsten carbide (product number T111338) to replace the modified tungsten carbide and using high-entropy alloy powder to replace the high-entropy alloy composite material, the Vickers hardness decreases, the fracture toughness reduces, and the flexural strength becomes smaller (Comparative Example 4); compared with Example 1, when using commercially available tungsten carbide (product number T111338) to replace the lanthanum-modified tungsten carbide and using high-entropy alloy powder to replace the high-entropy alloy composite material, the Vickers hardness decreases, the fracture toughness reduces, and the flexural strength becomes smaller (Comparative Example 5).

[0088] In summary, by selecting a composite hard phase formed by modified tungsten carbide and lanthanum-modified tungsten carbide, and introducing graphene-nickel composite powder into the binder phase high-entropy alloy to form a composite material, the present invention prepares an ultrafine cemented carbide tool material for high-temperature material processing, improves the Vickers hardness of the material, increases the fracture toughness, and obtains good flexural strength.

Claims

1. An ultrafine cemented carbide tool material for high temperature material processing, characterized in that: The composition comprises the following components in parts by weight: 46-50 parts of modified tungsten carbide, 42-46 parts of lanthanum-modified tungsten carbide, 4-12 parts of high entropy alloy and 0.2-0.6 parts of carbon powder; The preparation method of the modified tungsten carbide comprises: mixing and ball-milling 90-95 parts of tungsten carbide, 4-8 parts of tungsten powder, and 1-2 parts of graphene oxide by weight to obtain a mixed powder; hot-pressing and sintering the mixed powder to obtain a blank, and crushing the blank to obtain the modified tungsten carbide; The preparation method of the lanthanum modified tungsten carbide comprises: mixing 92-98 parts of tungsten carbide and 1-3 parts of paraffin wax by weight, and then adding 2-4 parts of lanthanum powder, 1.2-1.8 parts of boron nitride quantum dots and 40-50 parts of anhydrous ethanol for surface modification to obtain lanthanum modified tungsten carbide; The surface modification treatment conditions include: grinding in a planetary ball mill at a speed of 280-300 r / min for 8-10 hours, then vacuum drying at 70-80° C. for 3-5 hours, then keeping warm at 190-200° C. for 12-14 hours to remove paraffin, and cooling to room temperature; The preparation method of the boron nitride quantum dots comprises: mixing 2-6 parts of boric acid and 200-300 parts of deionized water, and then adding 0.6-0.8 parts of melamine for heat treatment to obtain boron nitride quantum dots; The high entropy alloy is a high entropy alloy composite material; the preparation method of the high entropy alloy composite material comprises: mixing 35 to 40 parts of cobalt powder, 20 to 25 parts of erbium powder, 25 to 30 parts of chromium powder, 5 to 10 parts of tungsten powder and 5 to 10 parts of ruthenium powder by weight, smelting, removing impurities, and then obtaining high entropy alloy powder by vacuum gas atomization granulation; mixing 90 to 100 parts of the high entropy alloy powder and 6 to 10 parts of graphene-nickel composite powder to obtain a high entropy alloy composite material.

2. The ultrafine cemented carbide tool material for high temperature material processing according to claim 1, characterized in that: The conditions of the ball milling treatment include: a rotation speed of 100-120 rpm, a time of 12-16 hours, and vacuum sieving through a 100-200 mesh sieve after the ball milling treatment.

3. The ultrafine cemented carbide tool material for high temperature material processing according to claim 1, characterized in that: The hot pressing sintering conditions include: filling the mixed powder into a mold, then putting it into a hot pressing sintering furnace, under the condition of a vacuum degree of 0.6-0.8 Pa, first heating to 900-1000° C. and keeping it warm for 10-20 minutes, applying a pressure of 110-120 MPa, then heating to 1700-1800° C. and keeping it warm for 30-40 minutes, cooling to room temperature, and releasing the pressure.

4. The ultrafine cemented carbide tool material for high temperature material processing according to claim 1, characterized in that: The mixing treatment conditions include: adding 100-120 parts of anhydrous ethanol and stirring for 1-3 hours, and then vacuum drying at 60-70° C. for 8-10 hours.

5. The ultrafine cemented carbide tool material for high temperature material processing according to claim 1, characterized in that: The preparation method of the graphene-nickel composite powder comprises: dispersing 10 to 20 parts of graphene oxide in 80 to 100 parts of deionized water, adding 10 to 20 parts of a nickel sulfate solution with a molar concentration of 1 mol / L and 2 to 6 parts of hydrazine hydrate for stirring reaction to obtain the graphene-nickel composite powder.

6. A method for preparing the ultrafine cemented carbide tool material for high temperature material processing according to any one of claims 1 to 5, characterized in that: The steps include: Step S1: by weight, 46-50 parts of modified tungsten carbide, 42-46 parts of lanthanum-modified tungsten carbide, 4-12 parts of high entropy alloy and 0.2-0.6 parts of carbon powder are mixed evenly, and then a molding agent paraffin is added for ball milling, and spray drying is performed to obtain a green body; Step S2: placing the green body in a vacuum environment, heating it to a temperature of 600-700° C. to remove the molding agent, then heating it to 1480-1500° C. and sintering it for 100-120 min, and cooling it to room temperature to obtain an ultrafine cemented carbide tool material for high temperature material processing.