Anti-corrosion film on 2024/SiC aluminum matrix composite fabricated by microarc oxidation in silicate electrolyte

A corrosion-resistant ceramic film was prepared on the SiC reinforced aluminum matrix composite by microarc oxidation technique in silicate solution. The film with two layer structure consists of mullite, α-Al2O3, γ-Al2O3 and amorphous SiO2. Analysis of microstructure and composition suggests that only a few SiC particles remain in the film close to the composite/film interface and most of SiC reinforcements have transformed into the oxides under plasma discharge sintering. By microarc oxidation treatment, the corrosion current density of 2024/SiC decreases almost four orders of magnitude. The corrosion resistance of the coated 2024/SiC composite was greatly improved because the SiC reinforcements had not disrupted the continuity of micoarc oxidation film.