G. Faghani - Department of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, Iran
S. M. Rabiee - Department of Materials Engineering, Babol Noshirvani University of Technology, Babol, Iran
S. Nourouzi - Department of Materials Engineering, Babol Noshirvani University of Technology, Babol, Iran
H. Elmkhah - Department of Materials Engineering, Bu-Ali Sina University, Hamedan, Iran

In this article, corrosion behavior of the single-layered TiN, single-layered CrN and multi-layered TiN/CrN coatings have been fabricated on 420C stainless steel (SS) by Cathodic Arc Evaporation (CAE) method in Ringer s solution was studied. The electrochemical appraisal was done by the Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) tests. Results of PDP test revealed that all coated specimens have an increment in the polarization resistance (Rp) values (ranges from 438.2 to 593.6Ω.cm2) compared to bare SS (268.1Ω.cm2). Corrosion rate values for bare 420C SS and CrN, TiN and multi-layered TiN/CrN coatings were measured 0.086, 0.042, 0.050 and 0.068mpy, respectively. Furthermore, EIS results were showed that the single-layer CrN coating well depicted by an equivalent circuit with three time constants and has larger impedance and maximum logarithmic variation of C2. Finally, the corrosion performance results confirmed that single-layered CrN coating is an appropriate choice for deposition on 420C SS with the aim of application in general surgical instruments.

420C stainless steel, corrosion, Multi-layer, Ringer s Solution, TiN/CrN