A method for producing a tungsten carbide-cubic boron nitride composite

Abstract

The application relates to a preparation method of a tungsten carbide-cubic boron nitride composite material, and belongs to the field of material engineering. The components of the tungsten carbide-cubic boron nitride composite material comprise the following components in parts by mass: 60-70 parts of tungsten carbide, 20-30 parts of cubic boron nitride, 5-15 parts of cobalt, 0.1-0.5 parts of chromium carbide, 0.5-1.5 parts of titanium carbide and 0.3-0.7 parts of aluminum. The tungsten carbide-cubic boron nitride composite material is prepared by adopting a hot-pressing sintering method, the balance between wear resistance and toughness is considered, the titanium carbide is a transition metal carbide, the bond type is mixed in the same crystal structure by ionic bond, covalent bond and metal bond, the performance of the composite material is further improved, the chromium carbide has the effect of inhibiting abnormal growth of tungsten carbide grains, the spherical crystal with uniform particle size can be obtained, the uniform dispersion of high-hardness cubic boron nitride can improve the wear resistance of the material, the dense structure of the submicron tungsten carbide ensures the good internal structure and mechanical properties of the material.

Description

Technical Field

[0001] This invention relates to the field of materials engineering, and specifically to a method for preparing a tungsten carbide-cubic boron nitride composite material. Background Technology

[0002] Tungsten carbide-based cemented carbide, as a common wear-resistant material, possesses excellent properties such as high hardness, high toughness, high elastic modulus, wear resistance, and corrosion resistance, and is widely used in cutting tools, mining tools, and wear- and corrosion-resistant components. However, cemented carbide tools suffer from rapid edge wear and short service life when used for high-speed cutting of difficult-to-machine materials such as chilled cast iron. While superhard materials such as cubic boron nitride and diamond have high hardness and good wear resistance, they have poor impact toughness, often resulting in chipping or even complete tool breakage during use. Furthermore, polycrystalline composite materials are often obtained using high-temperature and high-pressure methods, as illustrated in the papers by Jiang Wei et al., "Analysis of Bending Strength of PcBN Composite Sheets" and "Synthesis of Low-Content PcBN Composite Sheets under High Temperature and High Pressure." These high-temperature and high-pressure methods complicate the production process, increase the cost of the key consumable, the top hammer alloy, and result in a lower product cost-effectiveness, limiting their application and promotion. Summary of the Invention

[0003] Based on the above shortcomings, this invention proposes a method for preparing tungsten carbide-cubic boron nitride composite material.

[0004] This invention provides the following technical solution:

[0005] A method for preparing a tungsten carbide-cubic boron nitride composite material includes the following steps:

[0006] (1): The mass fractions of the tungsten carbide-cubic boron nitride composite material are as follows: 60-70 parts of tungsten carbide, 20-30 parts of cubic boron nitride, 5-15 parts of cobalt, 0.1-0.5 parts of chromium carbide, 0.5-1.5 parts of titanium carbide, and 0.3-0.7 parts of aluminum;

[0007] (2): Accurately weigh the above-mentioned mass fractions of raw materials, use a 360-degree all-round planetary mixer, add solvent and mix to obtain a slurry, then dry the obtained slurry in a vacuum drying oven, and sieve to obtain a uniformly dispersed mixture;

[0008] (3): The mixture obtained in step (2) is purified in a vacuum furnace;

[0009] (4): The powder obtained in step (3) is subjected to isostatic pressing to obtain the shape of the tool blank;

[0010] (5): The tool blank from step (4) is subjected to low-pressure sintering to obtain the tool blank;

[0011] (6): After grinding the tool blank from step (5) on the outside, the tool blank is sharpened to obtain the corresponding tool product.

[0012] Preferably, in step (1), the tungsten carbide powder has an average particle size of 0.8 μm and a purity of ≥99%; the cubic boron nitride powder has an average particle size of 2 μm and a purity of ≥99%; and the cobalt powder has an average particle size of 1 μm and a purity of ≥99%.

[0013] Preferably, the mixing conditions of the 360-degree planetary mixer in step (2) are: rotation speed 100-500 rpm, ball-to-material ratio 2:1-8:1, ball milling time 4-16 h, and solvent addition amount 120-240 mL / 100 g powder.

[0014] Preferably, the drying conditions for the slurry in step (2) are: drying at 80–140°C for 4–10 hours, with a vacuum degree ≤10. -2 Pa.

[0015] Preferably, the dried slurry in step (2) is passed through a 200-mesh sieve.

[0016] Preferably, the powder purification conditions in step (3) are: 200-400℃ for 1-4 hours, vacuum degree ≤10. -2 Pa.

[0017] Preferably, the isostatic pressing conditions in step (4) are 100-600 MPa.

[0018] Preferably, the sintering conditions in step (5) are: heating to 1300-1500°C at a rate of 2-10°C, and then holding at 30-60 bar for 1-4 hours.

[0019] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a simple operation method with easily controllable process conditions. Compared with commonly used high-temperature and high-pressure processes, the product has low internal residual stress. Chromium carbide inhibits abnormal growth of tungsten carbide grains, resulting in spherical crystals with uniform particle size. The uniform dispersion of high-hardness cubic boron nitride improves the wear resistance of the material. The dense structure of submicron-sized tungsten carbide ensures that the product has good internal structure and mechanical properties. The process method of this invention uses a conventional hot-pressing sintering furnace for sintering, reducing the performance requirements of production equipment, simplifying operation, and significantly improving economic benefits. It provides a high-performance, cost-effective tungsten carbide-cubic boron nitride composite material. Detailed Implementation

[0020] Next, the technical solutions in the embodiments of the invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1:

[0022] The preparation method of tungsten carbide-cubic boron nitride composite material includes the following steps:

[0023] (1) The tungsten carbide-cubic boron nitride composite material comprises, by mass parts: 60 parts tungsten carbide, 28 parts cubic boron nitride, 10 parts cobalt, 0.3 parts chromium carbide, 1.2 parts titanium carbide, and 0.5 parts aluminum;

[0024] (2) The mixture was mixed using a 360-degree planetary mixer with a rotation speed of 400 rpm, a ball-to-material ratio of 4:1, a ball milling time of 16 h, and an alcohol addition of 180 mL / 1000 g powder to obtain a mixed slurry.

[0025] (3) The mixed slurry was dried under vacuum at 120℃ for 6 hours and then passed through a 200-mesh sieve to obtain a uniformly dispersed powder;

[0026] (5) Vacuum purify the sieved powder at 400℃ for 4 hours, with a vacuum degree ≤10. -2 Pa;

[0027] (5) The purified powder is loaded into the mold, the static pressing molding condition is 400MPa, the hot pressing sintering temperature is raised to 1400℃ at a rate of 5℃, and held at 50bar for 4h.

[0028] Example 2:

[0029] The preparation method of tungsten carbide-cubic boron nitride composite material includes the following steps:

[0030] (1) A tungsten carbide-cubic boron nitride composite material, comprising, by mass parts: 65 parts tungsten carbide, 24 parts cubic boron nitride, 9 parts cobalt, 0.3 parts chromium carbide, 1.2 parts titanium carbide, and 0.5 parts aluminum;

[0031] (2) The mixture was mixed using a 360-degree planetary mixer with a rotation speed of 400 rpm, a ball-to-material ratio of 4:1, a ball milling time of 12 h, and an alcohol addition of 160 mL / 1000 g powder to obtain a mixed slurry.

[0032] (3) The mixed slurry was dried at 120℃ under vacuum for 6 hours and then passed through a 200-mesh sieve to obtain a uniformly dispersed powder.

[0033] (4) Vacuum purify the sieved powder at 400℃ for 4 hours, with a vacuum degree ≤10. -2 Pa;

[0034] (5) The purified powder is loaded into the mold, the static pressing molding condition is 400MPa, the hot pressing sintering temperature is raised to 1430℃ at a rate of 5℃, and held at 50bar for 4h.

[0035] Example 3

[0036] The preparation method of tungsten carbide-cubic boron nitride composite material includes the following steps:

[0037] (1) A tungsten carbide-cubic boron nitride composite material, comprising, by mass parts: 70 parts tungsten carbide, 20 parts cubic boron nitride, 8 parts cobalt, 0.3 parts chromium carbide, 1.2 parts titanium carbide, and 0.5 parts aluminum;

[0038] (2) The mixture was mixed using a 360-degree planetary mixer with a rotation speed of 400 rpm, a ball-to-material ratio of 4:1, a ball milling time of 10 h, and an alcohol addition of 120 mL / 1000 g powder to obtain a mixed slurry.

[0039] (3) The mixed slurry was dried at 120℃ under vacuum for 6 hours and then passed through a 200-mesh sieve to obtain a uniformly dispersed powder.

[0040] (4) Vacuum purify the sieved powder at 400℃ for 4 hours, with a vacuum degree ≤10. -2 Pa.

[0041] (5) The purified powder is loaded into the mold, the static pressing molding condition is 400MPa, the hot pressing sintering temperature is raised to 1450℃ at a rate of 5℃, and held at 50bar for 4h.

[0042] Table 1. Hardness, flexural strength, fracture toughness, and wear ratio of WC-cBN composite materials.

[0043]

[0044] This invention addresses the insufficient wear resistance of cemented carbide cutting tools by adding cubic boron nitride and titanium carbide hard phases with higher hardness. Titanium carbide, a transition metal carbide, has a bond structure consisting of ionic, covalent, and metallic bonds mixed within the same crystal structure, further improving the composite material's performance. Chromium carbide inhibits abnormal grain growth of tungsten carbide, and the cobalt binder coating results in spherical crystals with uniform grain size. The uniform dispersion of high-hardness cubic boron nitride enhances the material's wear resistance, while the dense submicron-sized tungsten carbide structure ensures excellent internal structure and mechanical properties. The table shows that as the cubic boron nitride content decreases, the composite material's toughness and flexural strength significantly increase. Compared to ordinary cemented carbide with a Vickers hardness of around 1500, the composite material exhibits significantly improved wear resistance. Compared to high-temperature, high-pressure polycrystalline cubic boron nitride materials, its toughness is greatly enhanced, achieving a balance between wear resistance and toughness. Therefore, the tungsten carbide-cubic boron nitride composite material processed in this application demonstrates significantly superior overall performance compared to existing technologies.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a tungsten carbide-cubic boron nitride composite material, characterized in that, Includes the following steps: (1): The mass fractions of the tungsten carbide-cubic boron nitride composite material are as follows: 60-70 parts of tungsten carbide, 20-30 parts of cubic boron nitride, 5-15 parts of cobalt, 0.1-0.5 parts of chromium carbide, 0.5-1.5 parts of titanium carbide, and 0.3-0.7 parts of aluminum; (2): Accurately weigh the above-mentioned mass fractions of raw materials, use a 360-degree all-round planetary mixer, add solvent and mix to obtain a slurry, then dry the obtained slurry in a vacuum drying oven, and sieve to obtain a uniformly dispersed mixture; (3): The mixture obtained in step (2) is purified in a vacuum furnace; (4): The powder obtained in step (3) is subjected to isostatic pressing to obtain the shape of the tool blank; (5): The tool blank from step (4) is subjected to low-pressure sintering to obtain the tool blank; (6): After external cylindrical grinding of the tool blank in step (5), the corresponding tool product is obtained; The tungsten carbide powder mentioned in step (1) has an average particle size of 0.8 μm and a purity of ≥99%; the cubic boron nitride powder has an average particle size of 2 μm and a purity of ≥99%; and the cobalt powder has an average particle size of 1 μm and a purity of ≥99%. The mixing conditions of the 360-degree planetary mixer in step (2) are: rotation speed 100-500 rpm, ball-to-material ratio 2:1-8:1, ball milling time 4-16 h, and solvent addition amount 120-240 mL / 100 g powder.

2. The method for preparing the tungsten carbide-cubic boron nitride composite material according to claim 1, characterized in that, The drying conditions for the slurry in step (2) are: drying at 80-140℃ for 4-10 h, with a vacuum degree ≤10. -2 Pa.

3. The method for preparing the tungsten carbide-cubic boron nitride composite material according to claim 1, characterized in that, The dried slurry described in step (2) is passed through a 200-mesh sieve.

4. The method for preparing the tungsten carbide-cubic boron nitride composite material according to claim 1, characterized in that, The powder purification conditions in step (3) are: 200-400℃ for 1-4 hours, vacuum degree ≤10. -2 Pa.

5. The method for preparing the tungsten carbide-cubic boron nitride composite material according to claim 1, characterized in that, The isostatic pressing conditions described in step (4) are 100–600 MPa.

6. The method for preparing the tungsten carbide-cubic boron nitride composite material according to claim 1, characterized in that, The sintering conditions described in step (5) are: heating to 1300-1500°C at a rate of 2-10°C, and then holding at 30-60 bar for 1-4 hours.

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