Sputtered silicon nitride coatings for wear protection

Abstract Silicon nitride films were deposited by r.f. sputtering on 304 stainless steel substrates in a planar r.f. sputtering apparatus. The sputtering was performed from an Si 3 N 4 target in a sputtering atmosphere of argon and nitrogen. The rate of deposition, the composition of the coatings, the surface microhardness and the adhesion of the coatings to the substrates have been investigated as functions of the process parameters, such as substrate-target distance, fraction of nitrogen in the sputtering atmosphere and sputtering pressure. Silicon-rich coatings have been obtained for nitrogen fractions below 0.2. The rate of deposition decreases continuously with increasing nitrogen fraction and decreasing sputtering pressure. It was found that the adherence of the coatings improves with decreasing sputtering pressure, almost independently of their composition.