Publisher Summary 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.

Contact Melting Heat Transfer and Lubrication

Melting heat transfer inside ducts and over external bodies

Contact melting during sliding on ice

Heat transfer - a review of 1993 literature

An enthalpy method is employed to solve transport processes associated with melting of an unfixed rectangular phase change material (PCM) in a low-gravitational environment. This method permits the phase-change problems to be solved within fixed numerical grids, hence eliminating the need for coordinate transformation. The PCM, initially at its melting temperature, is placed inside a rectangular enclosure. The lower surface of the container is then exposed to a uniform temperature higher than the PCM melting temperature. The difference in densities of solid and liquid causes a force imbalance on the solid in the gravitational and low-gravity environments. In the case where the density of the solid phase exceeds that of the liquid, the solid continually moves downward as melting progresses and hence generates a flow field within the liquid. The problem is formulated as a one-domain problem with the possibility of melting from all the PCM surfaces, and no approximation is mode about the liquid film...

Numerical solution for melting of unfixed rectangular phase-change material under low-gravity environment

One of the anomalous thermodynamic properties of water is that the melting point of ice decreases as the pressure increases. This behavior was discovered independently by Kirchhoff and Thomson. It inspired Reynolds to speculate that the pressure-melting of ice and snow might be responsible for the low coefficient of friction experienced during skating and skiing. According to him, the pressure applied by the skate on the ice surface would cause superficial melting, which in turn would lubricate the relative motion between skate and ice. Although the pressure-melting phenomenon received some attention from early tribologists, this interest decreased after Bowden and Hughes' work, which showed that the superficial melting under the skate is due to friction (viscous dissipation) in the water film. In this note the authors consider a different fundamental aspect of the pressure-melting of ice, namely the indentation caused by a flat solid that is pressed against a block of ice. Unlike in the work referenced above, there is no lateral motion between the solid body and the ice block. The only motion that occurs is the normal progress that the solid body makes into the ice. This motion is made possible by the melting of the ice situatedmore » in front of the body. In this way, the pressure melting process is related to the contact melting process that occurs when a temperature difference ({Delta}T) is maintained between the solid body and the phase-change material.« less

The Pressure Melting of Ice Under a Body With Flat Base

In this note the authors consider the motion of a cylinder through a block of ice. The cylinder is pushed laterally through the ice block. The ice melts over the leading portion of the cylinder, the water films acts as lubricant (flows around the cylinder), and refreezes over the trailing portion of the cylinder. A cross section through the embedded cylinder is shown. The same problem was solved first by Nye, who proceeded from the assumption that the thickness of the water proceeded from the assumption that the thickness of the water film is constant. The objective in this note is to present a general and formal treatment, in which the film thickness is allowed to vary around the cylinder. In this way they arrive not only at Nye's constant-thickness results but also at the limiting conditions under which those results are valid. The authors then extend the analysis to a cylinder with an elliptical cross section, and report also the shape of the cylindrical cable that moves through a block of ice.

P. A. Tyvand

Papers

The Pressure Melting of Ice Under a Body With Flat Base

The Pressure Melting of Ice Due to an Embedded Cylinder

Melting around a shaft rotating in a phase-change material