Brown Tungsten Oxide

Blue Tungsten Oxide Picture

Brown tungsten oxide is also called tungsten dioxide, which is named because it appearing in brown powder, the general process is calcinating ammonium paratungstate under 500°C in the air into tungsten trioxide, or reduced into blue tungsten oxide under 450°C hydrogen atmosphere.

The reduction of brown tungsten oxide process can be divided into two part: Firstly, brown tungsten oxide is reduced into tungsten dioxide under 630°C. And then reduced into tungsten powder under 820°C. The purpose of reduction is to make kalium control the particle size of tungsten powder in a certain degree. Then it is pressed in a special mould into rectangular bar. Put the bar in charge under hydrogen atmosphere and heat to 3000 degree celsius, then the density of tungsten bar can reach to 85% of the theory(19.3g/cm3). Then the tungsten bar can be processed in to tungsten rods of 3mm. Then it can be processed into tungsten filament of different dimensions.