Effect of Pretreatment Process on Properties of Aerospace Al-Li Alloy Sulfuric Acid Anodic Film

Abstract

Aiming at a new Al-Li alloy,by the use of optical microscope, SEM and EDS, we analyzed the effects of different pretreatment processes including alkali corrosion and tri-acid deoxidation on the appearance, corrosion resistance and fatigue properties of sulfuric acid anodic oxide coatings. which provided a theoretical basis for the design, selection, application and surface protection of Al-Li alloy structural components. We found that the corrosion degree of the Al-Li alloy surface by alkali corrosion was deeper than that of the tri-acid deoxidation process. The corrosion resistance at the grain boundary was poor, so the mesh surface morphology of the anodic oxide film was formed. The fatigue life of the samples treated with alkali corrosion was lower than that of the tr-ioxic acid treatment, the fatigue life of the samples subjected to sulfuric acid anodic oxidation is different. The effect of different pretreatment on the corrosion resistance of the sulfuric acid anodic oxide layer of Al-Li alloy is not significant.

Keywords

• Al-Li alloy
• culfuric acid anodic
• pretreatment process
• corrosion resistance
• fatigue performance