Investigations of CrN/TiO₂ coatings obtained in a hybrid PVD/ALD method on Al–Si–Cu alloy substrate

The paper addresses an important scientific topic from the utilitarian point of view concerning the surface treatment of Al–Si–Cu aluminum alloys with PVD/ALD hybrid coating deposition. The influence of the conditions of titanium oxide deposition in CrN/TiO₂ coatings on their structure and properties, in particular corrosion resistance, were investigated. The TiO₂ layer was produced by means of the atomic layer deposition (ALD) method with a variable number of cycles. Structural investigations were performed using scanning and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), and Raman spectroscopy methods. Electrochemical properties were analyzed using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. The CrN/TiO₂ hybrid coating with titanium oxide deposited at 500 ALD cycles showed the best corrosion properties. It was also found that the prerequisite for obtaining the best electrochemical properties was the amorphous structure of titanium oxide in the hybrid coatings tested. The high tribological properties of the tested coatings were also confirmed.