Nanoscale Friction Measurements Up to 750 °C

A new experimental capability for elevated temperature nanoscale friction measurement is described. Its stability and resolution were demonstrated in two case studies up to 750 °C. A stainless steel probe was used to study friction between steel and glass at 25, 200 and 400 °C. Friction forces were calibrated at temperature. The friction coefficient increased between 25 and 200 °C, but stick–slip was dominant at 400 °C due to chemical interaction between the stainless steel probe and the glass. This was verified by scanning Energy Dispersive X-ray Spectroscopy analysis. A WC–Co probe was used to study friction on a range of TiN-based and Cr₅₄Al₂₀C₂₆ (so named MAX-phase composition) coatings at 25, 400 and 750 °C. A maximum in friction coefficient was observed at 400 °C. The decrease in friction at 750 °C was associated with the formation of lubricating surface oxides and oxidation-associated surface roughening.