Solid Lubricants

Solid lubricants are utilized where

a.      operating conditions are such that a lubricating film may not be secured by use of lubricating oils or greases,

b.      contamination of lubricating oils or grease is unacceptable,

c.       the operating temperature or load is too high, even for a semi-solid lubricant to remain in position, and

d.      combustible lubricants should be avoided.

Solid lubricants are utilized either in the dry powder form or mixed with water or oil. The solids fill up the low spots in the surfaces of moving parts and compose solids films which have low frictional resistance. The usual coefficient of friction between solid lubricants is among 0.005 to 0.01.

The two most usual solid lubricants employed are following

 (a)       graphite, and

 (b)       molybdenum disulphide.