Al2O3-ZnO atomic layer deposited nanolaminates for improving mechanical and corrosion properties of sputtered CrN coatings

The 316 L Stainless Steel is widely used as structural material in marine applications and is subject to localized pitting corrosion in chlorinated environments. The main aim of the present work is the development of coatings that are alternately deposited by a combination of Physical Vapor Deposition (PVD) and Atomic Layer Deposition (ALD) techniques. Three different architectures PVD/ALD, ALD/PVD and PVD/ALD/PVD were studied. Atomic layer deposited Al2O3, ZnO and Al2O3-ZnO nanolaminates thin films were inserted as sealing, top or inter layers within CrN sputtered films. The texture modification, morphology, preferred orientation growth, mechanical properties, wettability and corrosion resistance were investigated. The nanoindentation measurements confirmed the increase of the hardness of the studied coatings. Electrochemical properties and corrosion behavior of these films were studied in NaCl solution. The PVD/ALD/PVD architecture was found to be the most efficient architecture to provide an improvement in corrosion resistance. The CrN/[Al2O3-ZnO]n/CrN coating presents the best corrosion protection performance with the lowest corrosion current. The combinatory approaches used, present a great potential for advanced coatings with specific compositions that can be effectively used for different applications, especially in corrosive environments.