The Microstructure and High Temperature Sliding Wear Behavior of Fe-Al Coating Produced by High Velocity Arc Spraying

The microstructure and sliding wear behavior from room temperature up to 650°C of Fe-Al intermetallic coating produced by cored wire and high velocity arc spraying (HVAS) have been investigated. X-ray diffraction (XRD), energy dispersion spectroscope (EDS), optical microscopy (OM) and scanning electron microscopy (SEM) were used to analyze the microstructure and sliding friction and wear mechanism of the coatings. Chemical analysis of the coating indicated the composition to be Fe-20.0Al-14.1O (at.%). The microstructure was found to consist of Fe₃Al, FeAl and α-Fe regions mainly, together with fine oxide (Al₂O₃) layers and a little Al. The results of sliding wear indicated that the Fe-Al coating exhibited low friction coefficient and low wear rate at elevated temperatures. The reason of the friction coefficient decreasing at elevated temperatures is that protective oxide film formed on the worn surface during sliding wear process. And delamination is the predominant wear mechanism of the coatings. The Fe₃Al and FeAl intermetallics which have higher strength and hardness at elevated temperatures can effectively resist crack initiation, propagation and splat fracture, thus resulting in excellent high temperature wear resistance of the Fe-Al coating.