ALUMINUM AND TI AL MULTILAYER PVD COATINGS FOR ENHANCED CORROSION-RESISTANCE/

Aluminium-based coatings are potential candidates for a sacrificial pr otection of steel. Such coatings, elaborated by magnetron sputtering, offer a good corrosion protection but often present poor tribological properties [1,2]. Cathodic are evaporation PVD process has outstanding potential to deposit corrosion-resistant coatings with relatively den se structure. Moreover, adherent coatings and large scale production c an be obtained. Aluminium, titanium and multilayer titanium/aluminium coatings have been deposited on steel substrates. The coating uniformi ty and homogeneity analysis were performed by optical and scanning ele ctron microscopy while energy dispersive X-ray microanalyses were carr ied out to check the coating composition. The corrosion behaviours of smooth and threaded coated samples were analysed from 5% salt spray ex posures and electrochemically characterized with voltamperometric meas urements. Titanium/aluminium multilayers on low carbon steel lead to b etter corrosion resistance than monolayer coatings. Vacuum coating tes ts, carried out on small parts by means of a barrel coater, led us to consider the process to be a possible alternative to the actual anti-c orrosion treatments of steel substrates, especially as a substitute fo r cadmium coatings.