Development of coatings based on Fe-Cr-Ni-Al for resisting fretting wear in the temperature range 20–700 °C

Abstract

Previous work by the present workers has indicated that sprayed molybdenum coatings on steel were beneficial in resisting fretting wear in the temperature range 20–300 °C. Beyond this temperature range the oxidation rate of molybdenum increased rapidly and limited its use. Such coatings were mixtures of metal and oxide and provided an elevated temperature “glaze” which appeared to lubricate the surface and to reduce significantly the level of fretting damage. In developing a coating for use over a wider temperature range, mixtures of elements were selected which would provide the possibility of surface glaze formation. Mixtures of Fe-Cr and Ni-Al alloys were arc sprayed onto a low alloy steel and tested under conditions of fretting at 20, 475 and 700 °C. Coatings containing iron and chromium developed a glaze oxide at 475 and 700 °C with resultant low wear. The nickel-based coating did not develop the glaze oxide at 475 °C but did so at 700 °C.