Duplex surface treatment of metallic alloys combining cold-spray and plasma electrolytic oxidation technologies
Résumé
Plasma electrolytic oxidation (PEO) is widely used to improve the corrosion and wear resistance of lightweight metals such as aluminium alloys by the formation of a ceramic oxide coating. However, the PEO process remains ineffective for ferrous metals and, when applied to magnesium alloys, oxide coatings are usually thin and porous. To overcome these limitations, the feasibility of applying a duplex treatment combining cold-spray deposition (CS) and PEO is investigated. Cold-sprayed aluminium coatings are deposited on magnesium (EV31) and steel (S235) substrates prior to PEO. Investigation of this duplex process evidences the efficiency of such a two-steps process to form thick, dense and crystalline alumina coatings on both magnesium and steel substrates. The growth kinetic of the duplex CS-PEO oxide layer is enhanced by a factor of 3 compared to single-step PEO processing of bulk aluminium substrates. Results are discussed by considering the effect of the porosity through the cold-sprayed aluminium coating on the mechanism of oxidation during the subsequent PEO treatment.
Domaines
Matériaux| Origine | Fichiers produits par l'(les) auteur(s) |
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