There are four main forms of solid lubricants:

1. Used as a lubricating film.

2. Used as a whole material

3. Used as composite materials

4. The powder is used as an additive in lubricating oil and grease. This method is simple, without additional device, and it is convenient to use.

Molybdenum disulfide powder and graphite powder are added as additives to lubricating oil and grease. These two kinds of lubricants are black, which will pollute the environment. BN is white and non-toxic. These properties are of greater significance for textile, food machinery and friction pairs working in high temperature environments.

Molybdenum disulfide is oxidized at 400 ℃ and graphite is oxidized at about 500 ℃, and then the crystal surface and structure change, so that the friction coefficient increases, the wear also increases, and the lubricating effect becomes poor. However, BN is still in a stable state at 900℃, and the friction coefficient does not change much at high temperature. Since the thermal stability of boron nitride is better than that of molybdenum disulfide and graphite, the lubricating performance of boron nitride added oil and grease is better than that of molybdenum disulfide and graphite added oil and grease. More and more users are replacing molybdenum disulfide or graphite with HBN.