Coatings tribology

Abstract

Optimization of coefficient of friction in association with minimum wear is a general requirement to reduce energy consumption due to friction and wear losses. Lubrication such as solid and liquid is utilized to meet low friction and wear demands. Extreme environmental conditions such as space and high-temperature applications limit their usefulness. There is a need to design newer class of coatings for such applications. Design and selection parameters of coatings and their tribology are discussed in this chapter. These parameters include scale-dependent failure modes (nano-and micrometer length scale), state of stress at the interface, material properties, and chemical interactions at the interface. The requirements for selection of coating for friction applications are included. Tribology of low-friction coatings such as graphite, molybdenum disulfide, diamond-like carbon, chromium-based coatings, and polymeric coatings is discussed. Effects for service conditions such as load, nitrogen, humidity, and temperature for selected coatings are listed. Knowledge of the interfacial phenomena plays very important role in selection and development of coatings for tribological applications.