Influence of Ce surface treatments on corrosion behaviour of A3xx.x/SiCp composites in 3.5 wt.% NaCl

The influence of silicon carbide particles (SiCp) proportion and matrix composition on aluminium metal matrix composites A3xx.x/SiCp modified by cerium-based conversion or electrolysis coating was evaluated in 3.5 wt.% NaCl at 22 °C using potentiodynamic polarization and gravimetric measurements. Ce-treated surfaces presented better corrosion behaviour in chloride media than original composite surfaces without treatment. Both treatments preferentially covered the intermetallic compounds and SiCp. The electrolysis afforded a higher degree of protection than conversion treatment because the coating was more extensive. Coating microstructure and nature of corrosion products were analysed by scanning electron and atomic force microscopy (SEM, AFM) and low angle X-ray diffraction (XRD).