Improvement of the adhesion of diamond-like carbon coatings induced by ion treatments

Diamond-like carbon (DLC) films, with and without nitrogen, were deposited using ion beam technique. Their film structural characterizations were analyzed by Raman spectroscopy and measurement of refractive index. The analysis results indicate that nitrogen-containing diamond-like film shows a higher I(D) to I(G) ratio and a lower refractive index than the film without nitrogen. The nitrogen incorporated into the film combined with ions’ bombarding the surface of the substrate prior to coating promotes film adhesion strength, nanohardness and wear resistance. N2 ion treatment also results in the better adhesion than both Ar and O2 ion treatments. Our results further demonstrate that nitrogen-containing DLC films were firmly deposited on the stainless steel without an intermediate layer. Such a layer is commonly used for other coating processes as a buffer layer to improve adhesion strength.