Development of Infrared Microscopy for Measuring Asperity Contact Temperatures

Abstract

Surface temperature measurements within sliding contacts are useful since interfacial heat dissipation is closely linked to tribological behavior. One of the most powerful techniques for such measurements is in-contact temperature mapping whereby a sliding contact is located beneath an infrared microscope. In this approach, one of the specimens must be transparent to infrared and coated such that radiation components can be distinguished and isolated from background values. Despite its effectiveness, a number of practical constraints prevent this technique from being applied to rough surfaces—a research area where temperature maps could provide much needed two-dimension input data to inform mixed and boundary friction models. The research described in this paper is aimed at improving the infrared temperature mapping technique in terms of validity, robustness, and spatial resolution, so that measurements of rough surfaces contacts can be made. First, Planck's law is applied in order to validate the use of surface coating as a means of removing background radiation. Second, a refined method of calibration is put forward and tested, which negates the need for a soft aluminum coating and hence enables rough surfaces to be measured. Finally, the use of super-resolution algorithms is assessed in order extend spatial resolution beyond the current limit of 6 μm.