Manufacture and characteristics of Al 2 O 3 composite coating on steel substrate by SHS process

Abstract Many steel components are needed to be reinforced on their surface to have a high abrasive resistance and corrosion resistance. Based on self‐propagating high‐temperature synthesis, a process to making Al 2 O 3 composite coatings on mild steel substrate in atmospheric environment with the help of simple auxiliary facilities was developed successfully. A pre‐coated bilayer coating was employed. The effects of Fe content in pre‐coated transition layer on phase composition, porosity and interfacial bonding were studied using scanning electron microscopy (SEM), energy‐dispersive spectrum (EDS) and X‐ray diffraction (XRD). The thermal shock resistance and abrasive resistance were investigated. When Fe content changes from 0 wt% to 50 wt%, the bond quality at first becomes better and then worse gradually. When Fe content is less 20 wt%, there is a small gap between the transition layer and the substrate; when Fe contents are 30 wt% and 40 wt%, working layer, the transition layer and the substrate bond together well. The working layer is mainly composed of Al 2 O 3 , Fe–Cr and Al(Cr) 2 O 3 phases and has a dense structure with porosity of less than 1%. The coating has a good thermal shock resistance and abrasive resistance. The abrasive resistance of the working layer is about ten times that of the substrate.