Growth Characteristics of Plasma Electrolytic Oxidation Coatings on Aluminum Alloys

Abstract

The ceramic coating on aluminum alloy was prepared in sodium metasilicate electrolyte by plasma electrolytic oxidation (PEO). The effect of PEO treating time on surface layer was investigated. The morphology and phase composition of the ceramic coatings were characterized by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The effect of the electrolyte contents on the growth mechanism, element distribution and properties of oxide layers were studied. Oxide coatings morphology is strongly dependent on PEO process time. The microdischarges characteristics were studied as well, and it is shown that size of microdischarges becomes larger with increasing time of PEO. XRD analysis showed that Plasma Electrolytic Oxidation coating has hard, dominantly Al2O3 phase.