An experimental investigation of the surface temperature of graphite in a sliding system using an infrared microscope

Several very important problems remain unsolved in the field of Tribology. For example, we do not know the detailed nature and distribution of the real areas of contact when one solid body slides over another. Furthermore, we know very little about the actual surface temperatures produced in such systems. These two important unknowns are related and formed the basis for an investigation conducted at Virginia Polytechnic Institute and State University.

An experimental apparatus, using a sliding system, was constructed to study these problems. The sliding system consisted of SA-35 graphite test specimens loaded against a rotating sapphire disk. A scanning electron microscope was used to obtain detailed information on the size and shape of the areas of contact between the graphite and the sapphire. The surface temperature in the area of contact was determined by using a Barnes Infrared Microscope which measured the radiance from the area of contact. Since the target spot of the microscope was much smaller than the areas of contact, the temperature distribution over the macroscopic area of contact could be determined. The results of the experimental study were compared with the temperature rises in the area of contact predicted by the theories of Blok, Archard, Jaeger, and Holm. Possible reasons for discrepancies between theory and experiment were also examined.