Preparation of Ultra Coarse Tungsten Carbide Powder in 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 China, the demand for hard alloy tools for rock breaking in the mountains is great, and the super coarse cemented carbide has strict requirements for the grain size of WC powder.

At present, the aggregation degree of ultra coarse tungsten carbide powder is high, the particle size is not coarse enough, and the coarse grain WC powder has WC particle aggregates. In the preparation of super coarse cemented carbide, it is very important to control the preparation of ultra coarse tungsten carbide powder.

The preparation method of ultra coarse grained tungsten cobalt hard alloy includes the following process steps: batching, wet grinding, drying, preheating, wet mixing, drying, blending agent, pelletizing, pressing molding and vacuum low pressure integrated sintering.

Ingredients selection of cobalt powder and tungsten carbide powder, cobalt powder and tungsten carbide powder quality ratio is 2.5: 97.5, tungsten carbide powder with particle size of 13 ~ 18.5 um single crystal close to ordinary coarse WC powder and the mass percentage of 2.5% particle size 1.4 ~ 2 mu m metal powder Co; At the same time, the increasing prefiring process improves the degree of inclusion of WC particles, and slows the irregular growth of WC grains during the sintering process. Wet grinding ball milling, milling medium for acetone, ball material ratio is 3: 1, solid-liquid ratio is 5: 1, wet grinding time is 7 hours; wet grinding after drying, drying the mixture after preheating, pre burn treatment after 4 hours of heating up to 700~850 DEG C, and insulation 60 minutes.

The mixture will burn after adding metal cobalt powder and Co2W4C nano particles, adding amount of cobalt powder to achieve the quality of cobalt and tungsten carbide mixture in the ratio of 8: 92, after mixing, heating to 60 DEG C and wet mixing for 4 hours; after drying, mixing forming agent, granulation and compression molding, vacuum pressure sintering temperature sintering integration, the highest is 1460 DEG C.

In general, through the above process, and high toughness ultra coarse tungsten cobalt alloy prepared by the last WC the average grain size of 5.2 um average bending strength is about 3400MPa, the hardness is up to HRA88.5, comparable with the foreign similar products.

• < Prev
• Next >