Cemented carbide is the tooth of mining tools, and its product quality has a great impact on the service life of mining tools. Among the quality characteristics of mining cemented carbide products, the composition and characteristics of cemented carbide are the keys to its performance. Therefore, to correctly select mining cemented carbide products, it is necessary to understand their composition and parameter characteristics.

Composition of mining cemented carbide

Mining Cemented Carbide is a two-phase composite material prepared from two materials, WC and Co, by optimizing the preparation process and organizational structure. Tungsten carbide is a hard and brittle material, and cobalt is a plastic material. While the composite of WC and Co produces the best combination of hardness and strength, it has superior properties to the component materials.

In the production of cemented carbide for mining, it is important to control the C content, above or below a very narrow range will produce free C or η phase. Even within the scope of the two-phase region, small changes in the C content will affect the composition of the binder phase, thereby changing the hardness, strength, toughness, and certain chemical properties of cemented carbides. For mining cemented carbides, controlling the C content on the upper limit side of the two-phase region is conducive to improving the toughness of cemented carbides, which is beneficial to the performance of cemented carbides.

The composition of cemented carbide for mining mainly depends on the grade design. After completing the grade design, the fluctuation of Co content is related to the powder weighing accuracy and sintering process. The factors affecting the C content of cemented carbides are much more complicated, which is the focus and difficulty of the quality control of the cemented carbide production.

Three factors affect the change in cemented carbides C content:

1. The total carbon test of WC powder is not accurate;

2. The oxygen content of the mixing material fluctuates greatly, which is related to the oxygen content of raw materials, storage method, storage conditions and time of the mixing material, and the button milling process, including button milling media and milling time, drying process methods, and the storage time of the soft billet;

3. It is related to the sintering process, including the sintering method, degreasing process, positive carbon process, control of equipment vacuum degree, and other factors.

Material Structure Characteristic of Mining Cemented Carbide

Mining cemented carbide is a two-phase composite material of WC and Co, and its performance has an important relationship with the structural parameters of the material. The main material structure parameters are WC average grain size, Co phase average free range, WC adjacency, and WC grain distribution.

The average grain size of WC is an important index. When the Co content is constant, the finer the WC grain, the higher the hardness of cemented carbides, and the lower the fracture toughness of cemented carbides.

The grain distribution of WC also has an important influence on the properties of cemented carbides. According to the distribution of WC grains, the cemented carbides have uniform structure carbides and non-uniform structure carbides. Uniform structure carbides are carbides with a normal distribution of WC grains. For it, the narrower the WC grain distribution, the better. Non-uniform structure carbides are the WC grain distribution that appears bimodal. Some studies have shown that non-uniform structural carbides have better wear and fracture resistance than uniform structural carbides with the same hardness. However, if the production process is not well-controlled, the appearance of coarse WC grains in non-uniform structure carbides will reduce the fracture resistance of carbides.