Deposition of corrosion-resistant chromium and nitrogen-doped chromium coatings by cathodic magnetron sputtering

This work deals with the realization of corrosion-resistant chromium-based thin films by cathodic magnetron sputtering. A systematic study of the deposition parameters (substrate temperature, pressure and gas mixture composition) has been carried out to determine the optimal conditions to obtain films with good corrosion resistance and also with good mechanical properties such as hardness, wear resistance and adhesion. The structure of the films has been determined by X-ray diffraction and their composition by X-ray photoelectron spectroscopy. The corrosion resistance of the samples has been characterized by an electrochemical method with a potentiostat and a synthetic sweat test. It is shown that the substrate temperature has a great effect on the film structure and texture. Appropriate doping with nitrogen makes it possible to increase the coating density and decrease the grain size, with a corresponding improvement in the corrosion resistance of the films. This doping also allows us to improve the microhardness up to 35 GPa.