Solution-Temperature-Controlled Growth of Microarc Oxidation Coatings on Aluminum Substrates

The growth of microarc oxidation (MAO) coatings on aluminum substrates was controlled via changing solution temperature from 10 to 60 °C. The results show that an elevation of the temperature lowers the applied voltage and the coating thickness. The coating formed in low-temperature solution demonstrates large-sized pores and contains lots of elements only originating from solute such as P, W, and V. On the contrary, numerous small-sized pores disperse homogeneously on the coating synthesized in high-temperature solution. It is assumed that the variation of solution temperature affects the dissolving capacity of the alkaline solution and the adsorptive capacity of solute anions, thus dominating the growth behaviors of MAO coating.