Structural and quantitative analysis of nitrided stainless steel coatings deposited by dc-magnetron sputtering

Stainless steel coatings were deposited at a low temperature on low-carbon steel and mono-crystalline silicon substrates by dc-magnetron sputtering in a reactive atmosphere of nitrogen at room temperature. The total mass flow of argon and nitrogen was kept constant (20 sccm) for all depositions and the nitrogen mass flow varied between 0 and 10 seem with increments of 1 se em, while the argon mass flow was decreased by the same amount. The element al composition of the coatings and their deposition rate were studied by Ru therford backscattering spectroscopy (RBS), by X-ray emission induced by ch arge particles (PIXE), and by nuclear reaction analysis (NRA). The nitrogen content was found to increase with increasing mass flow up to a saturation value of 40 at.%. A structural analysis by means of conversion electron Mo ssbauer spectroscopy (CEMS) and grazing incidence X-ray diffraction (GXRD) was also performed. The results indicated the presence of the so-called S-p hase, probably due to nitrogen in solid solution at interstitial sites in t he austenite lattice. The lattice expanded as the nitrogen mass flow increa sed. This phase is particularly interesting for industrial applications bec ause it increased the resistance to wear without compromising the corrosion resistance of the steel. (C) 2000 Elsevier Science B.V. All rights reserve d.