The Reason of WS2 Grease Good Lubrication Performance

WS2 grease has good lubrication performance, and can still play a good lubrication effect on mechanical equipment in high temperature, high pressure, high vacuum and other harsh working environments. What are the reasons for this?

WS2 grease is a solid lubricating material formed by adding tungsten disulfide powder into grease. Tungsten disulfide served as extreme pressure additive in the process. The tungsten disulfide in the mixture is coated on moving parts, which can effectively reduce the friction between objects and extend the service life of mechanical equipment.

tungsten disulfide lubricating grease image

The main reasons why WS2 grease exhibits a good lubrication performance at high temperature are as follows:

(1) Tungsten disulfide crystal has a layered structure, with weak combination between layers. It is prone to shear and slip, and has a low friction coefficient.

(2) Tungsten disulfide ultrafine powder is of layered structure, with the smooth surface.

(3) Tungsten disulfide has a stable molecular structure, showing good resistance to high temperature and extreme pressure;

(4) Tungsten disulfide can be slowly oxidized to form a dense protective layer of tungsten trioxide (WO3) even at the temperature of higher than 400℃. The formed tungsten trioxide inhibits further oxidation of tungsten disulfide. Owing to the low friction coefficient of tungsten oxide, the tungsten disulfide can still protect the metal surface from bonding.

tungsten trioxide image

Tungsten trioxide’s molecular formula is WO3 and its molecular weight is 231.85. Tungsten oxide is a light yellow triclinic powdery crystal. Tungsten trioxide is the most stable of the tungsten oxides, with a melting point of 1473℃, a boiling point of higher 1750℃ and a relative density of 7.16. It is insoluble in water and inorganic acids except hydrofluoric acid. It can be dissolved in hot concentrated sodium hydroxide solution and ammonia water to form soluble tungstate.