Uniform Coarse Grained Tungsten Carbide Synthesis

Because of its good performance, coarse grained tungsten carbide can meet the needs of hard alloys for mining, petroleum, and heavy machinery industries. The coarse, uniform and crystallized tungsten carbide powder is the key to the preparation of high performance coarse grained carbides.

Some scholars have invented a carbonization method that is different from the traditional method. Its main technical content is to increase the particle size of tungsten powder by controlling the gas flow during the reduction of tungsten hydrogen. The main steps are as follows:

Take blue tungsten oxide powder with Fsss particle size of 20μm as raw material, about 6kg of raw material per boat is loaded. The temperature of the reduction furnace was increased to 1000°C, steam and hydrogen were fed into the furnace to control the PH₂O into the furnace at 0.45. Then, the material was pushed into the boat and reduced for about 15 hours. After the material was discharged, the material was sieved and get rid of oxide skin to obtain coarse grained tungsten powder. The Fsss particle size is about 21 μm. The grains of the coarse-grained tungsten powder are coarse, relatively uniform, and have a very small amount of fine powder and good crystallization of the particles.

The obtained coarse-grained tungsten powder is carbonized in accordance with a known method, with a carbon content of 6.15%, and then carbonized in a carbonization furnace at a carbonization temperature of 2300° C. Carbonization time is about 2 hours. The carbonization atmosphere is hydrogen. The coarse-grained tungsten carbide agglomerates are crushed by a 1:1 ball-to-ball mill and sieved to obtain coarse-grained tungsten carbide powders. The obtained coarse-grained tungsten carbide powder has a particle size about 23.2 μm. The surface of the tungsten carbide powder particle is compact, smooth and crystallized very well.

Preparation of coarse-grained carbide grain tungsten powder by the above method has a series of advantages, and the obtained coarse-grain tungsten carbide powder is wet-milled with 9.5% metallic cobalt powder in a ball mill for 15 hours (material:ball=1:2 weight ratio). Sintered at 1450°C in vacuum, the hardness HRA of the alloy is 86, and the porosity according to ISO 4505 is A02B00, which is the standard coarse-grained carbide.

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