Blue tungsten oxide powder for transparent thermal insulation window film can be used to prepare tungsten powder by hydrogen reduction method. Provided that other conditions are invariant, the particle size of tungsten powder can be increased if the reduction temperature is increased, or the reduction time is prolonged or the H2/WO3-x ratio is decreased.
In addition, the appropriate reduction time should be selected in industrial production to make the reduction sufficient and prevent the furnace charge from flowing backwards. Under normal circumstances, the reduction time should be controlled between 1~2.5h. After the reduction time is selected, the appropriate tilt angle and speed should be selected according to the amount of feed. When the feeding amount is large, a small inclination angle and a large rotation speed are adopted to prevent the charge from naturally flowing forward along the inner wall of the furnace tube as they may cause the actual reaction time to be shortened, and the material reduction is incomplete.
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