The physiological corrosion resistance of plasma nanocoated 316L stainless steel was studied in protein-containing electrolytes using electrochemical methods. Plasma nanocoatings with thicknesses of 20-30 nm were deposited onto 316L stainless steel coupons in a glow discharge of trimethylsilane (TMS) or its mixture with oxygen gas under various gas ratios. The surface chemistries of the plasma nanocoatings were characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Corrosion properties of the plasma nanocoated 316L stainless steel coupons were assessed using potentiodynamic polarization, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) in phosphate-buffered saline (PBS) electrolytes that contain bovine serum albumin (BSA) or lysozyme. It was found that BSA adsorption on the plasma nanocoated 316L coupons was heavily favored. BSA adsorption on the plasma nanocoating surfaces could block charge-transfer reactions between the electrolyte and 316L substrate, and thus stabilize the 316L substrates from further corrosion. In contrast, lysozyme adsorption on the plasma nanocoated specimens was not as pronounced and mildly influenced the corrosion properties of the plasma nanocoated 316L stainless steel.
Keywords: 316L stainless steel; cyclic voltammetry; electrochemical impedance spectroscopy; plasma nanocoating; potentiodynamic polarization.