Influence of Power Supply Frequency on Microstructure and Properties of Micro-Arc Oxidation Coating on Aluminium Alloy

This paper studies the influence of current frequency on the micro-arc oxidation (MAO) process, microstructrue and the properties of the formed alumina coatings. The amount of discharge sparks increases and the spark moves more quickly with increasing the frequency of current pulse. SEM results show that the size of the discharge products decreases. The anodic cell voltage decreases with increasing the frequency of power supply, however, the cathodic cell voltage increases. The thickness and roughness of the coating produced using frequency of power supply 50 Hz are high. Increasing the frequency, the thickness of the coating decreases, but coating surface becomes even, and the coating possesses better corrosion protective property