The Study of Rare-earth Conversion Coatings on Aluminum Alloy

摘要

The performance of the cerium conversion coating on LY12 aluminum alloy was studied with surface analysis and electrochemical measurements. The morphology and the composition of the conversion coating were determined by SEM and XPS. Results demonstrated that the conversion coatings were inhomogeneous on microstructures. It was showed from the polarization curves that after treatment the corrosion potential of the aluminum alloy moved in negative direction while the pitting potential moved in positive direction, which showed that the alloy became much less sensitive to the pitting corrosion. The EIS data, analyzed by equivalent circuit, indicated the charge transferring resistance was notably increased due to the conversion coating.