INFLUENCE OF ION BOMBARDMENT ON CRITICAL LOAD OF CrN FILM DEPOSITED ONTO ALUMINUM ALLOY BY ARC ION PLATING METHOD

Abstract

To improve the adhesive strength between the film and substrate, ion bombardment is frequently performed before the deposition of thin film coatings. In this study scratch tests were carried out on aluminum alloy protected with CrN film coated by arc ion plating method. In order to investigate the influence of ion bombardment conditions on the adhesive strength between the aluminum alloy substrate and the CrN coating, the ion bombardment process was performed before CrN coating under several different bias voltages. The properties near the interface were analyzed using SIMS. As a result, the ion bombardment process had an optimum condition and excessive bias voltage reduced the critical load. A Cr rich layer forms near the substrate surface by implantation of Cr ions due to the high incident energy ions. The Cr rich layer is shallow for the high critical load sample, while the low critical load sample has a deep Cr rich layer. It appears that the adhesion strength between the substrate and the film will depend on the depth or intensity of this Cr rich layer.