Tungstic Acid Calcination Method Producing Yellow Tungsten Oxide

Tungstic acid calcination method producing yellow tungsten oxide is by drying and calcinating tungstic acid, it is common method in industry. It is recorded that tungstic acid is dried under 100℃, mainly by removing moisture absorbed in the product. Ammonia and combined water need to be calcinated under high temperature. Tungstic acid is dehydrated under 180℃, completely dehydrated under 500℃ and generate yellow tungsten oxide. Chemical reaction is: H₂WO₄=WO₃+H₂O↑

Nano Yellow Tungsten Oxide Preparation Method
1. Mix ammonia solution (13.4mol/L～15mol/L) and distilled water with ratio 1:1, dissolve tungstic acid in ammonia solution. Add citric acid with molar ratio 2~4 times than tungstic acid into solution.
2.Stirring for 8~12 hours under 80~90℃, light yellow and transparent gel is obtained.
3.Roasing the gel in infrared ray oven until the gel is color fading and swelling.
4.Move gel into batch type furnace and calcinate for 550~650℃ will get nano yellow tungsten oxide.

Tungstic acid is the combination of tungsten trioxide, mix with water under different ratio and forms. It can be divided into yellow tungstic acid, white tungstic acid and metatungstic acid, among which yellow tungstic acid is common seen. Tungstic acid can be used to produce tungsten powder and tungsten products, also used as mordants, pigments, dyes, inks, also used as raw material in oil industry and aerospace material.