Surface and Corrosion Evaluation of RF Magnetron Sputtering SiN Coatings Deposited on SS 316L Exposed to Chloride Media

Abstract

Silicon nitride (SiN) is a ceramic material with high hardness and good chemical stability. This particular material has promising properties for its potential use in biomedical materials. In this study, SiN coatings were deposited on 316L stainless steel using radio frequency (RF) magnetron sputtering to improve the corrosion resistance of the substrate. The samples were characterized using scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. The results show that the morphology, roughness, and porosity of the coating depend on the substrate temperature and the RF power applied. These characteristics strongly influence the corrosion behavior of the samples. The coatings were composed of Si, N, O, and Fe. The absorption bands of α-SiN and Si-O were also determined. The coatings applied at 300°C allow and increase the low-frequency impedance modulus in two orders of magnitude, notably increasing the corrosion resistance.