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Basic properties of nano tungsten disulfide films

wallpapers Industry 2021-11-01 PDF Format
Tungsten disulfide is a metallic, dark gray crystalline powder. It is a layered hexagonal crystalline structure with a density between 7.4 g/m3 and 7.5g/m3. From the microscopic point of view, tungsten disulfide crystal has three planar unit layers, respectively s-W-S. Tungsten atoms in the unit layer are surrounded by sulfur atoms. And sulfur atoms are triangular distribution, there are strong bonds between two connected atoms, the bandgap can reach 1.8eV high, different layers are connected by molecular force, bond force is very weak, leading to an easy disconnection between the two layers, which is why the solid lubrication performance of tungsten disulfide is excellent.
The following is a description of its characteristics
Stable physical and chemical properties
In the air, tungsten disulfide is very stable, in water, oils, alcohols, and other organic solvents. Due to its chemical inertia, chemical reactions cannot occur, it is also very stable, in addition, in the presence of radiation and corrosive acid and alkali, it also shows good performance. Tungsten disulfide also has some considerable properties, such as good adsorption on the metal surface, and does not react with the metal. It can dissolve in molten carbonate. In the case of oxidizer, can also be dissolved in a large amount of carbonate, with strong stability, can be widely used.
Special electrical conductivity
The electrical conductivity of tungsten disulfide film has very special characteristics. The inherent resistance of tungsten disulfide powder formed by compression will decrease with the increase of pressure. If it is heated in a vacuum, it will show a negative temperature characteristic, which is similar to that of a semiconductor, and the inherent resistance will decrease. However, if it is in the non-vacuum air state, the inherent resistance does not change significantly below 300C, and only increases sharply above 300%C.
The lubrication characteristics 
The friction coefficient of tungsten disulfide has a great relationship with the environment. The friction coefficient increases in the air, and becomes smaller in the vacuum. Even if the friction stops, the friction coefficient will increase because of the adsorption on the surface. The film made of tungsten disulfide has stronger environmental dependence and the friction coefficient will increase significantly in wet air. At room temperature, the tribological performance is high at high load and speed. Under the air condition, the temperature is slightly higher than normal temperature, with good wear resistance. When heated in contact with the active metal, it still has strong stability at high-temperature.

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