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Journal of Analytical Methods in Chemistry
Volume 2014, Article ID 503618, 10 pages
http://dx.doi.org/10.1155/2014/503618
Research Article

Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

1Universidad Autonoma del Estado de Morelos, CIICAp, Avenida Universidad 1001, 62209 Cuernavaca, MOR, Mexico
2Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Fisicas, Avenida Universidad s/n, 62210 Cuernavaca, MOR, Mexico
3Instituto de Investigaciones Electricas, Avenida Reforma 113, Colonia Palmira, 62490 Cuernavaca, MOR, Mexico
4Corrosion y Proteccion (CyP), Buffon 46, 11590 Mexico City, DF, Mexico

Received 28 May 2014; Accepted 23 July 2014; Published 25 August 2014

Academic Editor: Krishna K. Verma

Copyright © 2014 J. Porcayo-Calderón et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel) process was evaluated in ZnCl2-KCl (1 : 1 mole ratio) molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR) measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used.