TiAlN coatings deposited by r.f. magnetron sputtering on previously treated ASTM A36 steel

TiAlN films were deposited on ASTM A36 steel by RF reactive sputtering using a TiAl alloy target Ti/Al — 60/40 at.% in an Ar + N2 atmosphere. The films were produced at two different pressures relation (PN2/PTotal), 0.05 and 0.1 with a constant argon pressure. The coatings were grown on ASTM A36 steel samples at a substrate temperature of 230 °C with different initial conditions: as delivered, hard and quenched, plasma nitriding, previously coated with Ti or TiN. The TiAlN films displayed mainly a Ti2Al3N composition with a (h00) preferential orientation, which increases by increasing the pressure ratio from 0.05 to 0.1. Samples with the higher homogeneity obtained with a pressure ratio of 0.1 also displayed the highest values of hardness (around 2500 HK), corrosion and wear resistance and the highest adherence was observed in samples coated at a pressure ratio of 0.05.