Effect of Nitrogen Flow Rate on Properties of CrN_x Coatings Prepared by Reactive Magnetron Sputtering

CrN_x coatings were prepared by reactive magnetron sputtering with controlled nitrogen flow rates (20-60 cm³·min^-1) on stainless steel and silicon chip substrate, respectively. The influence of nitrogen flow rate on the phase composition, microstructure, nanoindentation mechanical properties, tribological properties, and electrochemical corrosion resistance in 3.5wt% NaCl solution of the coatings was investigated. The results show that the CrN_x coatings all had columnar crystal structures at different nitrogen flow rates. With the increase of nitrogen flow rate, the phase composition of the coatings changed in order of Cr, Cr₂N and CrN; the nanoindentation hardness and elastic modulus increased first and then decreased; the average friction coefficient and the wear rate decreased first, then increased and then decreased; the corrosion resistance got better first and then got worse. When the nitrogen flow rate was 30 cm³·min^-1, the coating had a dense structure and the best mechanical properties, wear resistance and corrosion resistance.