Duplex TiN coatings deposited by arc plating for increased corrosion resistance of stainless steel substrates

• Published in: Surface & coatings technology Vol. 114; no. 2; pp. 129 - 136
• Main Authors: Rudenja, S., Leygraf, C., Pan, J., Kulu, P., Talimets, E., Mikli, V.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 12.05.1999; Elsevier
• Subjects: AISI 304; Applied sciences; Arc plating; Corrosion resistance; Duplex coatings; EIS; Exact sciences and technology; Metals. Metallurgy; Mott–Schottky plot; Nonmetallic coatings; Production techniques; Stainless steel; Surface treatment; Corrosion resistance; Arc plating; Duplex coatings; Stainless steel; Mott–Schottky plot; AISI 304; EIS; Austenitic stainless steel; Stainless steel-304; Titanium nitride; Steel; Experimental study; Corrosion protection; Protective coatings; Vacuum deposition; Surface treatment; Thin film
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/S0257-8972(99)00033-X

The corrosion performance of coatings depends on both the substrate and coating properties. In this work, duplex TiN coatings were deposited on AISI 304 stainless steel with arc-ion plating. Before deposition, nitriding of the substrate was done with a N + 2 ion energy of 500 eV or 700 eV in the same physical vapor deposition plant. The corrosion performance of the duplex TiN coatings was evaluated in an acidic chloride solution by using electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The measurements were also performed on the uncoated substrates for comparison. It was observed that the nitriding pretreatment leads to a high corrosion resistance of the substrate due to the formation of a highly protective passive film on the surface. For the coated system, the electrochemical behavior seemed to be dominated by the TiN coating. However, the formation of a thin oxide film on the surface of the TiN coating was also evident from Mott–Schottky plot measurements that indicate a n-type semiconducting behavior. The high donor density obtained suggests that the oxide film is very thin and probably amorphous. The oxide film formed on the TiN coating may be an important factor influencing the corrosion performance of the coated substrate. A model was proposed for the interaction between the duplex coating and aqueous solution which leads to the formation of a passive oxide film on the surface.