Characterisation of Oxide Coatings Produced on Aluminium by PEO at Different Frequencies of Pulsed Current
The Plasma Electrolytic Oxidation (PEO) is a surface modification process that allows producing protective oxide coatings on light metal alloys. These coatings are characterized by high microhardness and wear resistance. Changes of electrical conditions of alternate current during process, such as duration and frequency of anodic and cathodic pulses, influence on layer growth rate, its microstructure and final properties. In this study aluminium samples were oxidized at different electrical parameters in sodium silicate electrolyte. The growth rates of oxide layers were determined by mass change and thickness measurements. The microstructure of the obtained coatings was investigated by using scanning electron microscope. Additionally, phase compositions of coatings was determined by X-ray diffraction on top surfaces of layers. Generally, shorter duration and higher frequency of anodic pulses provides more uniform structure at lower growth rate. Nevertheless, there are certain ranges of electrical parameters that provide decent uniformity of oxide coatings.
H.K. Chikwanda and S. Chikosha
W. Gebarowski et al., "Characterisation of Oxide Coatings Produced on Aluminium by PEO at Different Frequencies of Pulsed Current", Materials Science Forum, Vols. 828-829, pp. 427-432, 2015