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Composite Binderless Tungsten Carbide

Compared with the pure WC binderless tungsten carbide, the physical properties such as hardness and elastic modulus of the composite binderless tungsten carbide may be slightly reduced, but generally have better sintering properties and can be to some extent. Reduce the amount of WC used, thereby reducing production costs. Further, depending on the additive, the properties such as thermal conductivity and wear resistance of the sintered body may be improved. Therefore, composite binderless tungsten carbide has attracted more attention from scholars.
Up to now, the composite binderless tungsten carbides that have been developed mainly include WC-TiC-TaC, WC-TiC, WC-Mo2C, WC-MoC, WC-Sic and WC-MoC-SiC.

WC-TiC-TaC
The WC-3wt% Tac cemented carbide developed by a Japanese company is subjected to ordinary atmospheric pressure sintering and then subjected to HIP treatment to obtain a dense sintered body. This binderless tungsten carbide has a higher hardness and a significant improvement in corrosion resistance as compared with the widely used WC-Co alloy. At present, this alloy has been widely used as a raw material for some mechanical seal parts of precision molds, mirror tools or nuclear power generation, and this alloy has also been widely used in optical molds.

WC-TiC
Although the composite binderless tungsten carbide exhibits good hardness, the toughness of the sintered body decreases as the TiC content increases due to the lower toughness of the TiC. When the addition amount of TiC is 50 mol%, the fracture toughness value of the sintered body is only 1/2 of that of pure WC. And since the elastic modulus of Tic is lower than the elastic modulus of WC, it is expected that as the Tic content increases, the elastic modulus of the sintered body also decreases.

WC-Mo2C
The hardness of the sintered body is lowered due to an increase in the amount of addition of Mo2C. However, when the addition amount of Mo2C is 6 wt%, the Vickers hardness of the composite binderless tungsten carbide is still as high as 21 GPa. At the same time, the fracture toughness of the sintered body increases as the amount of Mo2C added increases. It conforms to the change rule of hardness and toughness of general cemented carbide. Like the WC-TiC composite unbonded phase sintered body, the elastic modulus of Mo2C is only 391 GPa, which is also lower than WC. As the Mo2C content increases, the elastic modulus of the sintered body may also decrease.

binderless tungsten carbide plate picture binderless tungsten carbide rod picture

WC-Sic
The WC-Sic composite binderless tungsten carbide is the best sintered material in the binderless tungsten carbide currently developed. When the addition amount of the SIC is 0 to 20 mol%, a dense sintered body can be obtained under the conditions of 1600 ° CSPS sintering or 1750 ° C atmospheric pressure sintering. However, when the SIC content is higher than 20%, the density of the sintered body is greatly lowered.
WC-SiC binderless tungsten carbide not only has high hardness and elastic modulus, but also has higher thermal conductivity than general binderless tungsten carbide due to the addition of high thermal conductivity SIC. Also, since the elastic modulus of the SIC is low, the elastic modulus of the sintered body gradually decreases as the SIC content increases. The hardness is closely related to the change of WC grain size caused by the different SIC addition amount, and it tends to decrease first and then increase. This type of composite binderless tungsten carbide is currently used in the fine grinding mold industry on a small scale.

WC-MoC
The WC-MoC composite binderless tungsten carbide is a solid solution hard alloy. The WC-20 mol% MoC composite unbonded phase sintered body obtained by the SPS sintering technique has an elastic modulus of 660 GPa, a Vickers hardness of 24.1 GPa, and a fracture toughness of 5.73 MPa.m 1/2. After the annealing treatment, although the density of the sintered body is further increased, the crystal grains grow. The WC-20 mol% MoC composite binderless tungsten carbide after annealing at 2000 °C has an elastic modulus of 667 GPa, a Vickers hardness of 21.6 GPa, and a fracture toughness of 5.33 MPa.m 1/2. It is also possible to obtain a WC-MoC composite binderless tungsten carbide having excellent properties by sintering using a solid solution.

WC-MoC-SiC
WC-MoC-SiC composite binderless tungsten carbide is developed on the basis of WC-MoC composite binderless tungsten carbide, and has more than WC-MoC composite tungsten carbide. Good sintering performance and further reduced the use of high-priced WC. By adding SIC, the solid solution of Mo2C and C in the WC phase is promoted while improving the sinterability. A dense SIC composite binderless tungsten carbide was obtained at 1600 °C using SPS technology with an elastic modulus of 615 GPa, a Vickers hardness of 23.2 GPa and a fracture toughness of 5.7 MPa.
After the addition of SIC, the sinterability of the sample was significantly improved, and a dense WC-MoC-SIC composite binderless tungsten carbide was obtained at 1900 °C. As the SIC content increases, the elastic modulus of the sintered body decreases, but the hardness and fracture toughness hardly change with the change in the amount of SIC added. The SIC composite binderless tungsten carbide prepared by the atmospheric pressure sintering method has an elastic modulus of 610 GPa, a Vickers hardness of 20.7 GPa, and a fracture toughness of 5.5 MPa.m 1/2.

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1.Tungsten Carbide
2.Tungsten carbide Balls
3.Tungsten Carbide Rods
4.Tungsten Carbide Inserts
5.Tungsten Carbide Plates


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