P. Battersby

Fundamental study of generation of interfacial temperatures with metal surfaces and coatings under conditions of sliding friction and mechanical impact

Abstract The measurement of surface temperatures generated by sliding friction is discussed and experiments are carried out using dynamic thermocouples to determine surface temperatures arising from sliding friction and mechanical impact. Experimental results over a very wide range of loading and velocity conditions show an appreciable degree of similarity with calculated values using the equations given in part one of this study. Impacts with a 7·3 kg projectile with nickel and nickel coated test heads onto an angled steel anvil, have shown that very high transient surface temperatures can be reached. At velocities above 5 m s−1, surface temperatures in excess of 1000°C are obtained within a contact duration of less than 2 ms. The lower temperatures recorded in the case of impacts involving nickel plated steel test heads correspond to the temperature difference across the thickness of the coating rather than to the difference in surface temperature and the cold junction.

Fundamental study of generation of interfacial temperatures with metal surfaces and coatings under conditions of sliding friction and mechanical impact Part 1 - Thermal analysis and theoretical evaluation of surface temperature

Abstract A study has been carried out to evaluate the surface temperatures reached on sliding metallic surfaces over a wide range of conditions. This is of interest for a number of reasons, including determining the conditions of mechanical sliding friction which might be associated with failure or loss of adhesion of a coating intended to prevent galling or seizure and establishing the likelihood of igniting any pyrophoric substances present on the surface. In Part 1 of the study, the uncertainties involved in determining the surface temperature are considered and a thermal analysis performed to illustrate how variations in the properties of the contacting surfaces, together with the loading and sliding conditions influence the surface temperature. A numerical analysis of the heat transferred into the bulk of the metal indicates that in many cases the generated temperature increase will significantly decay over a comparable depth to that of an engineering metal coating.