High temperature wear behavior of Fe-Al coating prepared by high velocity arc spraying

Fe-Al intermetallic coating was prepared on a mild steel substrate making use of high velocity arc spraying (HVAS). The high temperature wear behavior of the resulting Fe-Al intermetallic coating against Si₃N₄ under dry sliding up to 650°C was investigated on a ball-on-disc test rig. The friction and wear mechanisms of the coating were discussed, based on the morphological observation of the worn surface and cross-section on a scanning electron microscope and the elemental composition measurement thereon by means of energy dispersive spectrometry. It was found that the friction coefficient of the coating decreased and the wear resistance significantly increased with increasing testing temperature. This was attributed to the solid lubricity of the oxide protective layer formed on the worn surface by way of tribochemical reactions and to the good ability of the Fe₃Al and FeAl intermetallics to retain higher strength and hardness at elevated temperatures. Namely, the Fe₃Al and FeAl intermetallics of higher strength and hardness at elevated temperatures made it possible to effectively resist crack initiation, propagation, and fracture, which largely accounted for the excellent wear resistance of the Fe-Al coating sliding against the ceramic counterpart at elevated temperatures. Moreover, the Fe-Al intermetallic coating was dominated by delamination as it slid against the ceramic counterpart at elevated temperatures.