The method for the determination of tungsten trioxide in tungstic acid is mainly based on the weight method of cinchonine. The principle is that the tungstic acid is separated from the impurities by using cinchonine hydrochloride in a hydrothermal solution with pH value of 3.00-4.4, And then burning it to get the product of tungsten trioxide, the final weighing, colorimetric to determine the content of tungsten trioxide.

There are four general tungsten oxides, yellow tungsten oxide, blue tungsten oxide, brown tungsten oxide and violet tungsten oxide. Among them, the violet tungsten oxide formed by the needle-like shape is the most special. Violet tungsten oxide is one of the most widely used raw materials in the production of tungsten powder. It is very important to identify the quality of violet tungsten oxide.

Ammonium paratungstate formation mechanism is due to the tungstate in the form of tungstate tungsten ions in solution, when the solution is acidified, the tungstate will react with hydrogen ions to produce a variety of polyoxometalates of tungsten ions. The reaction can be expressed as:

Tight tungsten is a chemically stable substance that is not oxidized at room temperature. When heated to high temperatures above 400 ℃ can be completely oxidized to tungsten trioxide.

Tungsten powder compacts principle is the powder forming process, the powder densified into a certain nature, size, porosity and strength of the green body process. The physical and mechanical properties of tungsten powder are related to the density and strength of green compact. The density and strength of green compact are related to the characteristics of the material such as the morphology and size distribution of tungsten powder.

The high strength green compact tungsten powder is one of the important raw materials for large-diameter thin-walled tubes and thin tungsten plates with increasing demand in recent years. The quality requirements of related products are also getting higher and higher.

In nature, platinum group elements are known as precious metals with gold and silver. Platinum, iridium, rhodium, palladium are found in the platinum metal family. The most important value of platinum is not that it is a white gold jewellery, but that platinum is an important industrial catalyst.

Nanocrystalline cemented carbide has excellent properties such as high strength, high toughness, high hardness, good wear resistance and heat resistance, which is difficult to be produced by conventional materials. Nano tungsten powder is the key raw material to prepare nano carbide carbide.

Studies have shown that tungsten can effectively reduce the phase transition temperature of vanadium dioxide, copper can enhance the conductivity of vanadium dioxide.

Bismuth tungstate is a photocatalyst in the field of star products, due to its narrow band gap (about 2.7eV), in response to 400-460 nm of visible light, but due to the Bi₂WO₆ structure by WO6 eight surface layer and Bi₂O₂ layer composed of alternating layers of features, making it easy to form assembled by nanoplates of 3D structure, it can not only provide more sex sites for the photocatalytic reaction, but also have better recycling and recycling, thus showing potential application value in environmental purification.