Stress, porosity measurements and corrosion behaviour of AlN films deposited on steel substrates

Aluminium nitride films have been deposited on steel substrates (304L and m ild steel), in the: aim of realising anti-corrosion coatings. The adhesion of the films can be notably improved, by the presence of thin AIN(x) underl ayer, (unfortunately the galvanic coupling between aluminium and steel lead s to a fast degradation of the coatings) or by increasing the substrate tem perature. Stress measurements showed that the role of temperature in the im provement of the coatings adhesion can not be explained by a decrease of th e stress in the film. Electrochemical tests pointed to the fact that the pr otection of the 304L stainless-steel and mild-steel substrates by AIN coati ngs is due to its insulating nature. However, this protection is, to a grea t extent affected by the open porosity of the films that remains quite high . (C) 2000 Elsevier Science S.A. All rights reserved.