TBO is the abbreviation for tungsten blue oxide. It is not a defined tungsten compound, but a powdery mixture of multiple tungsten compounds whose chemical composition and physical properties are changing. Tungsten blue oxide is gradually replacing traditional tungstic acid and yellow tungsten oxide (tungsten trioxide) to become an important tungsten intermediate compound.
TBO is generally composed of ammonium tungsten bronze, hydrogen tungsten bronze, tungsten trioxide (WO3, yellow tungsten oxide), β-tungsten oxide (WO2.9, blue tungsten oxide) and γ-tungsten oxide (WO2.72, violet tungsten oxide).
The color of tungsten blue oxide changes continuously with the oxygen index (O/W) from 2.72 to 3.0. It means the color of tungsten blue oxide changes continuously with oxygen index from purple to yellow.
Tungsten blue oxide is prepared by calcinating APT in the absence of air or under the condition of hydrogen or hydrogen-nitrogen mixed gas. The large variation of TBO in composition is mainly depended on the reduction temperature, reducing atmosphere and reduction rate of APT. And it is also related to the actual reduction process.
More details, please visit:
http://www.tungsten-powder.com/Blue-Tungsten-Oxide.html
