Preparation of Tungsten Carbide with Ultra Coarse Grained Cemented Carbide

With the continuous development of the hard alloy industry, the requirements of tungsten carbide powder for its raw materials are becoming higher and higher. In particular, the preparation of super coarse cemented carbide, such as mine, machinery and drilling, has strict requirements for the grain size of tungsten carbide powder.

At present, the agglomeration degree of domestic tungsten carbide powder is high, and the particle size of powder is not big enough. Coarse grain tungsten carbide powder has the illusion that the WC particle aggregate is small. The wear resistance and toughness of the cemented carbide products are seriously affected. The cost of imported WC powder is high, which is not conducive to domestic scale production. So many domestic enterprises have done a lot of homework in the research and development of ultra coarse tungsten carbide, and made great progress.

It has been found that adding a small amount of cobalt in the process of carbon distribution can increase the particle size of tungsten carbide powder and improve the quality of cemented carbide sintered at last.

The pretreated mixture is added to cobalt powder and Co₂W₄C nanoparticles. The ratio of cobalt powder to tungsten carbide is 8 to 92. Co₂W₄C nanoparticles should be added in an amount such that the mass ratio of cobalt to Co₂W₄C nanoparticles in the mixture is 1:0.045, and the mixture is heated to 60°C and wet mixed for 4 hours; The high toughness ultra coarse grained cemented carbide obtained by drying and mixing agent, pelletizing, pressing molding and vacuum low pressure integrated sintering is the highest temperature of the vacuum low pressure integrated sintering, which is 1460 degrees.

After testing, the hard alloy product in the average size of WC reached 4 ~ 5.2 m, high toughness, and complete crystallization, fewer defects, low micro strain, subgrain thick uniform, high microhardness, wear resistance and impact toughness can be improved greatly, the flexural strength reached 3000 ~ 3400MPa, hardness HRA88.0 ~ 90.8, to achieve a good matching of strength and hardness.

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