Improvement of corrosion behavior of aluminum alloy/silicon carbide composites with lanthanum surface treatments

The effect of lanthanum-based conversion or electrolysis coating on the corrosion resistance of metal matrix composites consisting of Al alloy A3xx.x and silicon carbide (SiC) particles was investigated. Lanthanum-treated surfaces had better corrosion behavior in chloride media than original composite surfaces without treatment. Both treatments preferentially covered the intermetallic compounds and SiC particles. The electrolysis afforded a higher degree of protection compared to the conversion treatment because the coating was more extensive. ne coating microstructure and nature of corrosion products were analyzed using scanning electron and atomic force microscopy (SEM and AFM), and low-angle x-ray diffraction (XPD).