Effects of Pulse Duration on Structure and Surface Characteristics of Micro-Arc Oxidation Coatings Formed on Aluminum Alloy

Abstract

Micro arc oxidation (MAO) of aluminum alloy samples was studied using bipolar pulses with various pulse durations under constant duty cycle. The processing times were chosen as 20, 30 and 40 minutes. The X-ray diffraction (XRD) technique, scanning electron microscope (SEM), surface roughness measurement (R-a) and indentation tests were employed to investigate the phase distribution, microstructure, surface properties and hardness of the coatings, respectively. By increasing the pulse duration and processing time, coatings with different surface roughness, thickness and hardness were fabricated.