ABSTRACT

Mechanical components cease to be useful due to three main reasons: (1) obsolescence due to changes in design, material shortage, and various economic or safety factors, (2) irreversible gross deformation and fracture due to stresses exceeding the bulk strength of the material, and (3) surface degradation due to the loss of material as a result of wear and corrosion. Although there is not much to say about obsolescence, and bulk deformation and fracture are relatively well understood, loss of material due to wear and corrosion continues to be an enormously expensive problem to society. While both wear and corrosion involve complex phenomena, understanding of corrosion is signiŸcantly more advanced compared to wear. A concise deŸnition of wear is the removal of material from solid surfaces due to the eµect of mechanical action [1]. In the past, there was less interest in wear because worn parts were discarded and replaced by new ones. ˜is notion has changed in more recent years because of the dramatic decrease in tolerances of mechanical systems, advances in precision manufacturing, and development of in situ diagnostic methods. In today’s industrialized world, wear is a limiting factor in most machines, equipment, and manufacturing processes. Reducing wear (and friction) has also important implications in energy savings and environmental pollution.