Abstract: Micro-arc oxidation (MAO) is a novel surface ceramic coating technique, based on a plasma discharge treatment in aqueous electrolyte on aluminium surface by using high polarized voltage. An alumina coating was produced
by MAO on aluminium matrix composite. The results of XRD and SEM show that the alumina coating consists of α-Al₂O₃, γ-Al₂O₃ and ε-Al₂O₃. The adhesion of the
coating to the substrate is fine. Many crater-mouth like products formed by the plasma discharge observed on the coatings surface, indicate that the plasma discharge products can be generated in the discharge
channels. The maximum hardness value detected at around 12μm from interface of substrate/coating is 21GPa. The potentiodynamic polarization analysis results of the coating indicate that the MAO coated
aluminium matrix composite possesses excellent corrosion resistance.

Key words: aluminium matrix composite, micro-arc oxidation, alumina, ceramic coating