Microstructure and Corrosion Properties of PEO Coatings Produced on AM-Aluminum Alloys

Abstract

Aluminum alloys are one of the main materials employed in aerospace and automotive applications. One of the problems that affect these alloys in certain application is the poor corrosion resistance that can, however, be enhanced with proper surface treatments, such as anodizing. Among these treatments, Plasma Electrolytic Oxidation (PEO) is one of the most promising and the production of PEO coatings on traditional aluminum alloy was extensively studied in literature. Recently, the production of a lot of components is going into the direction of using innovative manufacturing systems and customized components, with improved mechanical and physical properties, can be manufactured by additive manufacturing (AM) techniques. Among the AM methods, laser-based AM has an immense potential for producing fully dense metallic structures, using a variety of available metal powders and has attracted more and more attention. The resulting AM samples are characterized by different microstructures in comparison with the conventionally manufactured ones and this can cause differences also in the production of PEO coatings and other surface treatments. Objective of the present work is to produce PEO coatings on AM samples in order to increase the corrosion and wear performances of the samples. PEO coating were produced on the samples testing different parameters and the coatings were characterized, in terms of microstructure and composition, with SEM analysis. The corrosion resistance of the samples was also evaluated with electrochemical tests. The results were compared with the ones obtained on traditionally manufactured samples. PEO coatings were successfully produced on AM samples obtaining samples with good coatings thickness and improved corrosion performances compared to the untreated ones.