Tungsten blue oxide is the full name of TBO, which is not a defined tungsten compound, but a powdery mixture of tungsten trioxide, β-tungsten oxide (blue tungsten oxide), γ-tungsten oxide (violet tungsten oxide), ammonium tungsten bronze and hydrogen tungsten bronze. And the chemical composition and physical properties of BTO are changing.
TBO may be produced by calcinating ammonium paratungstate (APT) in the airtight space or under hydrogen atmosphere/hydrogen-nitrogen mixed gas.
The composition of TBO varies greatly on the basis of reduction temperature, reducing atmosphere and reduction rate of APT. And the actual reduction process also has an important effect on TBO’s composition.
The color of TBO changes continuously from violet to yellow with the oxygen index (O/W).
Gradually, tungsten blue oxide is replacing tungstic acid and tungsten trioxide to become an important tungsten intermediate compound, for producing tungsten powder with different grain size such as tungsten nanopowder, ultrafine tungsten powder and so on.
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