A new strategy to prepare alumina-zirconia composite or multilayered coatings by combining cold-spray deposition and plasma electrolytic oxidation

In the present study, the feasibility of the elaboration of alumina (Al2O3) - zirconia (ZrO2) composite coatings on steel was explored by combining cold-spray deposition and plasma electrolytic oxidation (PEO). More specifically, two different configurations were investigated. The first configuration consisted in successively cold-spraying an aluminium layer first and a zirconium layer second, giving rise to a Zr / Al metallic multilayer coating that was then partially oxidized by PEO. In this configuration, microstructural characterizations evidenced the formation of a ZrO2 / Zr / Al composite multilayer coating on steel. The second configuration consisted in simultaneously cold-spraying aluminium and zirconium into a (Zr, Al) metallic composite monolayer prior to its partial oxidation by PEO. In this case, results evidenced the formation of a (ZrO2, Al2O3) / (Zr, Al) composite multilayer coating on steel. Finally, the present study demonstrated that the duplex surface treatment combining cold-spray deposition and PEO method is viable as a new route to produce ceramic/metal composite coatings on various metallic alloys.