XPS-SIMS studies of boron nitride films on type 316 stainless steel

By means of the combined use of X-ray photoelectron spectroscopy (XPS)and secondary ion mass spectrometry (SIMS), the chemical composition and surface distribution of boron nitride (BN) thin films on stainless steels AISI 316 type, have been studied. The BN thin films have been grown by thermal treating in dissociated NH3 the austenitic steels that were characterized by a low content of nitrogen and doped with different amounts of boron. XPS depth profiles and SIMS high spatialres olution elemental images have evidenced that boron segregates and reacts with dissociated NH3 only at the grain boundaries in the low boron doped steel and forms essentially boron nitride. By contrast, in high boron doped steel, boron nitride layer almost uniformly covers the surface and extends into the bulk of the alloy. In this latter material, SIMS images have disclosed at the grain boundaries the presence of other nitrides such as AlN, CrN and SiN as well as the formation of complex carbide-nitride-boride species.