Tungsten Dioxide
Introduction
Name: Tungsten Dioxide
Formula: WO2
Molecular Weight：215.84
Melting Point: 1500~1600℃
Boiling Point: 1730℃
CAS: 12036-22-5
Appearance: Brown Powder
Density:10.9~1.1g/cm3
Risk Code: 37
Safety Instruction: 26-36
CBNumber：CB5421675
MOL File：12036-22-5.mol
Solubility: insoluble in water, alkali solution, hydrochloric acid and sulfuric acid
Property
It is dissolved in sulfuric acid to form a red salt, easily oxidized and convert to high valence of tungsten trioxide by nitric;
Easy disproportionate in an inert gas to produce metal tungsten and tungsten trioxide;
decompose when heating to melt in the N 2 gas stream under 1500~1600℃;
At high temperature (1020 ℃) when hydrogen gas can be reduced to metallic tungsten;
It is stable in 45% to 60% of water vapor at 900℃ and 40% to 55% of hydrogen;
It will quickly oxidized to tungsten trioxide in the air, and transformed to blue tungsten oxide when heated to 500 ℃ in a nitric oxide gas;
Preparation
It comes from tungsten trioxide by the reduction of hydrogen under 575~600℃, or the reduction of metal tungsten and tungsten trioxide;
Mix tungsten powder and WO3 at the molar ratio of 1:2 and heated to 950℃ in the vacuum atmosphere;
Or restore the WO 3 at the condition of 900℃ in the H2 airflow with saturated steam.