An investigation of thermal sprayed aluminum/hard anodic composite coating on wear and corrosion resistant performance

Abstract

Thermal sprayed coatings were developed mostly for wear and corrosion resistance in numerous applications such as power generating, steel, chemical and aerospace industries. In this investigation, a composite coating consists of thermal sprayed aluminum layer and anodic film on AISI 1020 steel was introduced. A series of measurements including coating thickness measurement, roughness testing, micro hardness testing and SEM observation were performed to identify the characteristics of the composite coating. Electrochemical AC impedance test was used to examine the corrosion resistance property of this composite coating. A ball-on-plane wear test was executed in room temperature by using the oscillation friction wear tester based on ASTM D6425-99 to determine its wear performance. The wear and corrosion performance of composite coatings was strongly influenced by the coating structure and the surface condition of the thermal sprayed aluminum layers on which the anodic films were deposited. The corrosion and wear resistance of thermal sprayed aluminum coating were obviously enhanced after anodizing. The anodic films deposited at low current density (1-2ASD) were uniform and less defects, it show a better wear and corrosion resistance than those deposited at high current density.