Blue Tungsten Oxide And Purple Tungsten Oxide
At present, the production of ultra-fine tungsten powder, use purple tungsten and tungsten blue two kinds of raw materials exist simultaneously, and therefore these two materials were compared, hydrogen reduction experiments under the same conditions, compare the restored tungsten powder particle size and uniformity of the difference to determine exactly what kind of material is more suitable for the production of ultra-fine tungsten powder. From the microscopic structure and the reduction mechanism of both raw materials analyzed two kinds of raw materials caused by the tungsten powder particle size reduction of hydrogen production and uniformity of the reasons for the differences.
Tungsten oxide reduction process, the particle size will usually change. Currently, the main theoretical explanation W powder particle size reduction process variations have two:
1) growth mechanism of chemical vapor migration. Tungsten and their oxides in contact with steam, will generate a volatile hydrated tungsten oxide (WO2 (OH) 2), evaporated to a homogeneous gas phase reduction reaction occurs with the H2, the reduction product of metal tungsten has been deposited on the nucleation of on the grain, so that the tungsten powder particles grow. This process is the reaction rate, the reduction product forms and materials will change significantly compared.
2) solid-phase local chemical reaction. Solid tungsten oxide contact occurs with H2 gas - solid reaction of oxygen atoms with the gradual removal of lattice rearrangement. This process is slow reaction rate and the reduction product form does not changed.