Contact Melting Heat Transfer and Lubrication

The subject of this chapter is the relatively recent work on melting and lubrication at the interface between two solid parts, one of which is at its melting point. It is an area of research that began in heat transfer, with studies of contact melting inside capsules and around embedded objects. Melt lubrication is now a distinct topic in tribology. The classical application of melt lubrication is in the area of sliding friction on ice and snow. Among the more modern applications is the coating of a metallic part with another metal whose melting point is considerably lower. The function of the latter is to melt and serve as lubricant in a manufacturing process to which the former may be subjected. The research reviewed in this chapter covers the contract melting of crystalline substances, anomalous crystalline substances such as ice, and the contact softening of glass-like substances. These occur in diverse contact-region geometries. The shapes of the mating solid surfaces may be concave, convex, or plane, while the perimeter of plane contact regions may be either rectangular or circular. The types of relative motion reviewed are sliding contact, rolling contact, the movement of a hot body through a melting solid medium, and the movement of a solid melting inside a heated capsule. The effect, the roughness, or contact melting over the tops of asperities is also analyzed.