The preparation and properties of black coating by micro arc oxidation on 2A12 aluminum alloy

Black micro arc oxidation coating was prepared on 2A12 aluminum alloy in the electrolyte based on Na2SiO3, Na3PO4, NaOH, EDTA-2Na and NH4VO3, Na2WO4, KMnO4, Cu(CH3COO)2 as additives. The surface and cross-section morphology, elemental composition, chemical state, bonding force and polarization curve of black micro arc oxidation coating were analysised. The results prove that a black coating is prepared after adding additives. The main elements of black coating are Al, O, Si, V, Mn, Na, P, K, Cu. These elements are mainly present in the form of oxides. The critical load of black micro arc oxidation coating is 16.25N. The self-corrosion potential is increased by 0.2 V compared with the substrate, the corrosion current density is reduced by 1/2.