When blue tungsten oxide has same quality, the reduction process plays an important role at tungsten powder particle size. In producing fine tungsten powder must be strictly controlled reduction of temperature, hydrogen flow rate, hydrogen gas humidity, the thickness of the material layer, through hydrogen speed and direction, as they will influence fine tungsten powder producing.
Firstly, hydrogen-way requirements, generally speaking, there are two ways through hydrogen: cis hydrogen and inverse hydrogen. When the hydrogen reduction reaction at low temperatures and low humidity conditions, following hydrogen flow direction to push the boat along will obtain fine tungsten powder which is better than using inverse hydrogen way produce tungsten powder.
For another requirement is the reduction temperature, the higher reducing temperature the faster response, the more intense vapor transport, resulting in crystalline powder. And tungsten powder will agglomerate and coarse. Therefore, during the reaction the temperature should use low starting point, warmed gently heating system. Because the reduction temperature is low, heating will not so fast, so the water for the reaction is not too much which is in favor of the producing fine tungsten powder.