In: Chemistry
As mentioned in the question I am discussing about only solid lubricant
Definition
Solid or dry lubricant are materials which are able to reduce friction between two surfaces sliding against each other without the need for a liquid oil medium.
Application
Solid lubricants are useful for conditions when conventional lubricants are inadequate, such as:
Examples of solid lubricant
The two main dry lubricants are graphiteand molybdenum disulfide. They offer lubrication at temperatures higher than liquid and oil-based lubricants operate. Dry lubricants are often used in applications such as locks or dry lubricated bearings. Such materials can operate up to 350 °C (662 °F) in oxidizing environments and even higher in reducing / non-oxidizing environments (molybdenum disulfide up to 1100 °C, 2012 °F). The low-friction characteristics of most dry lubricants are attributed to a layered structure on the molecular level with weak bonding between layers. Only layered structure is not sufficient such layers are able to slide relative to each other with minimal applied force, thus giving them their low friction properties.