The
corrosion resistance of anodized 17% SiCp/2024 Al metal matrix composite (MMC) was evaluated using potentiodynamic polarization
and the drop test. The morphologies and microstructures of the
anodized film were observed with optical microscope, SEM and TEM. The film composition was analyzed by EDXS. The polarization results show that the anodized film provides satisfactory corrosion protection in 3.5% NaCl aqueous solution, and its corrosion rate is more than 2 orders of magnitude lower than that of the untreated sample. SEM morphologies show that SiC particles can hinder the growth of the film. The thickness of the film formed at low current density of 5 mA/cm2 is thinnest, its structure is compact, pores are small in size, and the film exhibits much better
corrosion resistance. TEM observation indicates that the pores near SiC particles are more in quantity and bigger in average size than that away from SiC, the biggest size of pore is about 50 nm. This shows that the film on anodized MMC possesses the microstructural features of lower corrosion resistance. EDXS shows that part of the SiC particle could be oxidized when the MMC was anodized in H2SO4 solution.