Dry lubricants or solid lubricants are materials which, despite being in the solid phase, reduce friction between two surfaces sliding against each other without the need for a liquid media. Such lubricants, including materials such as graphite, hexagonal boron nitride, molybdenum disulfide (MoS2) and tungsten disulfide are also able to offer lubrication at temperatures higher than liquid and oil-based lubricants are able to operate. Such materials can operate up to 350°C in oxidizing environments and even higher in reducing / non-oxidizing environments (molybdenum disulfide up to 1100°C).
The low-friction characteristics of most dry lubricants are attributed to a layered structure on the molecular level with weak bonding between layers. Such layers are able to slide relative to each other with minimal applied force, thus giving them their low friction properties. Solid lubricants are also characterized by high resistance to pressure and aging, in addition to having excellent anticorrosive properties.
The dry lubricant coatings:
-Apply to surfaces where lubrication is difficult or impossible with traditional greases and oils.
-They are particularly suitable in areas with extreme conditions (high or low temperatures, pressure, vacuum…).
–Repel dirt and environmental dust.
–Form a permanent film between contact surfaces, fill existing imperfections.
–Modify the coefficient of friction between metal parts, thus favoring the sliding and wear is reduced.
Solid Dry Coating
This is how it woks
1. Partial separation of the solid lubricant film.
2. Transfer of the solid lubricant to the opposite contact surface.
3. Lubricant film formation between both surfaces.