The electrochemical behavior of thermally oxidized CrN coatings deposited on steel by cathodic arc plasma deposition

• Published in: Applied surface science 2004-09, Vol.236 (1-4), p.406-415
• Main Authors: Chang, Ku-Ling, Chung, Shih-Chun, Lai, Shih-Hsiang, Shih, Han-C.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Corrosion resistance; CrN; Cross-disciplinary physics: materials science; rheology; EIS; Exact sciences and technology; Physics; Thermal oxidation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2004.05.024

Cathodic arc plasma deposition of the CrN coating has been applied to an industrial scale to improve the corrosion resistance of the AISI 304 stainless steel. Thermal oxidation in air was carried out at the temperature of 500 and 800°C for 1h. The effect of the thermal oxidation on the aqueous corrosion behavior of the CrN/304s assembly was investigated in this study. The composition and structure of the CrN coatings were studied by the grazing X-ray diffraction (GXRD), electron probe X-ray microanalyzer (EPMA), and X-ray photoelectron spectroscopy (XPS). The polarization resistance (Rp) of all samples was measured and compared in terms of a polarization resistance resulting from electrochemical impedance spectroscopy (EIS) in a mixture of 0.5M H2SO4 + 1M NaCl solution. The results indicated that the corrosion resistance of the CrN coated steel oxidized at 500°C is significantly reduced. On the contrary, the electrochemical behavior of the CrN coated steel oxidized at 800°C shows better corrosion resistance than the one oxidized at 500°C and as-deposited steel. After thermal oxidation at 800°C, the oxide layer formed on top of CrN coating enhances the corrosion protection of the CrN coated steel.