EFFECT OF MICRO-ARC OXIDATION COATINGS ON CORROSION RESISTANCE AND MECHANICAL PROPERTIES OF CLOSED-CELL ALUMINUM FOAMS

Micro-arc oxidation (MAO) coatings were prepared on closed-cell aluminum foams. The microstructure, elemental distribution and phase composition of the MAO coatings were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The corrosion resistances and compressive properties of the uncoated and coated aluminum foams were studied by electrochemical polarization test and mechanical test, respectively. The results show that the MAO coatings cover the surfaces of closed-cell aluminum foams. The average thickness of the MAO coatings is 7 μm. The MAO coatings are mainly composed of γ-Al2O3 phase. The corrosion resistances of the closed-cell aluminum foams are improved by MAO treatment. The as-received foams show a low corrosion potential (-1.36 V), on contrary, the MAO coated foams get an increase corrosion potential (-0.78 V). But the MAO coated foams show the marginal variation in compressive strengths when the thickness of the coatings could be negligible compared with the total thickness of the foams.