Al, Al–N alloy, and AlN-coated steel corrosion behavior in O2-free KCl solutions

Abstract

Al, Al–N alloy cermet, and AlN films were grown on 1008 steel substrates using reactive sputter deposition. Corrosion rates of the steel+coating composite in an O2-free 0.2M KCl electrolyte were measured under conditions of cathodic polarization. The results show that an AlN coating lowered the corrosion rate of steel by over an order of magnitude. However, the corrosion rate was enhanced and under certain conditions exceeded that of steel when Al–N alloy cermet and Al coatings were used. This phenomenon was explained in terms of a reactive porous electrode model.