Investigations of CrN+Cr₂O₃/TiO₂ coatings obtained in a PVD/ALD hybrid method on austenitic 316L steel substrate

The study investigated hybrid coatings CrN + Cr₂O₃/TiO₂ type obtained using the hybrid PVD/ALD technology on a substrate made of Cr-Ni-Mo (316L) stainless steel. Coating of CrN + Cr₂O₃ was obtained by the Arc-PVD method. TiO₂ using atomic layers deposition was investigated. It were deposited at a variable number of cycles from 200 to 1000 cycles at a constant temperature of 200 °C. Structural studies using scanning and transmission electron microscopy and atomic force microscopy were performed. The chemical composition analysis in the micro-regions was performed using EDS. The study of electrochemical properties was performed using potentiodynamic method and electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution. As a result of the study, it was found that the best electrochemical properties were shown by hybrid coatings for which the TiO₂ layer was obtained in 500 ALD cycles. Based on microscopic studies with diffraction and spectroscopic analysis, the structure of the tested coatings was related to electrochemical properties, and the influence of deposition conditions on corrosion resistance was explained. In addition, the tests were supplemented with tests of tribological properties and adhesion of coatings to the substrate.