Structure and properties of PVD coatings deposited on aluminium alloys

Abstract

Investigation results concerning microstructure and mechanical properties of the bilayer coatings are presented in this work. Gradient/monolithic coatings [Ti/Ti(C,N)-gradient/CrN, Cr/CrN-gradient/CrN] were deposited onto the aluminium alloy (Al–Si–Cu) substrate by cathodic arc evaporation method. The microstructure of the achieved layers was examined using TEM and SEM. Change of the chemical composition was measured using a glow discharge optical emission spectrometer. The physical vapour deposition coating structure is composed of small crystallites with an average size between 15 and 20 nm, depending on the coating type. Images (SEM) showed that the deposited coatings are characterised by compact structure without delamination or defects and that they closely adhere to each other. The Ti(C,N)/CrN coatings demonstrate the highest hardness and abrasive wear resistance.