Research on Corrosion Behavior of Typical Aluminum Alloy Bottom Layer in Neutral Salt Spray Environment

Abstract

To study the protective effect and corrosion law of aluminum alloy bottom layer in neutral salt spray environment,neutral salt spray test was conducted with the anodized film,hard anodized film,chromized film and phosphorus chromized film as the research objects,to investigate the corrosion resistance and corrosion propagation performance of these four bottom layers applied togather with organic coating on four aluminum alloy substrate materials,namely 7075,2A12,6063 and 5A06,and to analyze their corrosion laws.Furthermore,the corrosion appearance and adhesion of scratch-free specimen as well as the maximum corrosion width of the specimen with scratches were tested.And the corrosion failure,variation in adhesion and corrosion propagation resistance test results of six aluminum alloy bottom layers based on four aluminum alloy materials were obtained under neutral salt spray test environment.Results showed that different types of aluminum alloys had an important effect on the protective performance of the bottom layer under neutral salt spray environment.The performance of aluminum alloy bottom layer played an important role in improving the protective system.Sealing treatment could significantly improve the corrosion resistance of anodized film and hard anodized film and also their adhesion strength to organic coating.The adhesion strength was not a decisive factor in the corrosion resistance of the coating system.

Keywords

• aluminum alloy|corrosion resistance|salt spray test|anodizing|hard anodizing|chromizing film|phosphorus chromizing film