ABSTRACT
In most tribological applications, liquid or grease lubricants are used to combat friction and wear; but when service conditions become very severe (i.e., very high or low temperatures, vacuum, radiation, extreme contact pressure, etc.), solid lubricants may be the only choice for controlling friction and wear. Some of the key advantages of solid lubricants in tribological applications over liquid and grease lubricants are summarized in Table 22.1. A combination of solid and liquid lubrication is also feasible and may have a beneficial synergistic effect on the friction and wear performance of sliding surfaces. Solid lubricants can be dispersed in water, oils, and greases to achieve improved friction and wear properties under conditions of extreme pressures and/or temperatures (Barnett, 1977; Broman et al., 1978; Kimura et al., 1999; Erdemir, 1995).
