Blue tungsten oxide powder, or WO2.9, which may be used to prepare thermal insulating glass material, is also a raw material for preparing ultrafine tungsten powder. Some researchers have studied the process of preparing ultra-fine tungsten powder by blue tungsten oxide hydrogen reduction method. And they mainly studied the effects of reduction temperature and heating rate on the particle size of tungsten powder. So, what effect does the reduction temperature and heating rate have on the particle size of tungsten powder?
Since the process of hydrogen reduction of tungsten oxide belongs to gas-solid heterogeneous reaction type, the migration speed of gas phase directly affects the speed of reaction and the morphology of final product. The higher the reduction temperature, the faster the reaction rate. And the gas phase migration is more intense, which promote the sintering and recrystallization of the powder. Therefore, the powder forms powder agglomerate, so that tungsten powder particles are easily coarsened. On the contrary, when the reduction temperature is low and the temperature rising process is relatively gentle, the reaction speed is moderate and the gas phase migration is stable, so the water vapor generated by the reaction is easily diffused and escaped, which is more favorable for preparing fine grain size tungsten powder.
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