STUDY OF MIXED RARE EARTH METAL (REM) CONVERSION COATING ON ALUMINUM ALLOY LY12

The process of mixed rare earth metal (REM) conversion coating on aluminum alloy LY12 (2024) is introduced in this paper. The corrosion resistance of mixed REM conversion coating is examined by weight loss test and electrochemical method. The results show that mixed REM conversion coating increases the corrosion resistance of the alloy surface. Examination of scanning electron microscope (SEM) shows that the coating exhibits honeycomb-like feature. X-ray diffraction (XRD) analysis reveals that the coating is amorphous. The result of X-ray photoelectron spectroscopy (XPS) indicates that mixed REM conversion coating consists predominantly of Ce and O. The contents of other rare earth elements (La, Pr) are relatively low.