Cast tungsten carbide is one of the tungsten based hard surface materials widely used in petroleum, mining, metallurgy, agricultural machinery and other industries. Its structure is eutectic structure of WC and W2C (WC·W2C), with high hardness, high melting point and other characteristics. Cast tungsten carbide as wear-resistant material can be used to prepare high quality drill bits and wear-resistant surfacing parts of various equipment. In practical application, casting tungsten carbide is usually used as the hard phase and ni-based self-fusion alloy as the bonding phase. Welding layers applied in various industrial fields are prepared by oxy-acetylene surfacing, plasma surfacing, laser cladding, oxy-acetylene spray welding and other processes. The quality of tungsten carbide powder of hard phase casting directly affects the properties of welding layer. On the one hand, the chemical composition of high-quality cast tungsten carbide should be controlled, such as total carbon, free carbon and impurity elements (Fe, Ni, Co, etc.). On the other hand, the physical properties of cast tungsten carbide powder, such as powder morphology, particle size composition and eutectic structure content, should be controlled. The microstructure of cast tungsten carbide is usually dendritic or feathery. The method to determine the content of eutectic structure is to analyze the metallographic structure of cast tungsten carbide particles of a certain size and determine the content of the eutectic structure observed in the metallographic structure.

Cast tungsten carbide powder, as an important hard surface material, is playing an increasingly important role in the surface wear protection of power, energy, petroleum, chemical industry, metallurgy, machinery and other industrial components. The traditional production method of tungsten carbide is to mix the tungsten carbide powder, tungsten powder and the returned material in the production process with a certain carbon content, and then conduct smelting. Most of the produced tungsten carbide powder particles are in flake, long strip or multi-angle shape, and the acicular eutectic structure content in the crystal is low. This powder in surfacing coating or laser cladding, often in the coating form a large stress concentration, and under the pressure of easy to produce surface cracks, and fracture failure. In the 1990s, spherical cast tungsten carbide powder was prepared in the United States, Germany, Canada and other countries. Compared with traditional tungsten carbide, spherical casting tungsten carbide has two significant advantages. One is that the appearance is regular and spherical, the powder has good fluidity and wettability, and it can combine well with surrounding tissues after being added as an additive particle. Second, tungsten carbide particles have dense internal organization, good toughness, fine grain, high hardness, good wear resistance of coating and not easy to break and fail under the action of load. Due to its excellent performance, spherical cast tungsten carbide powder is gradually used in mining machinery, petroleum machinery, construction industry and foundry and other parts.

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