Corrosion and wear behavior of ultra-hard Ni-Cr electrodeposits on CK45 steel substrate obtained from Cr(III) based baths

Articles in Press

Document Type : Research Paper

Authors

1 Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, 61357-83151, Iran

2 عضو هیات علمی گروه متالورژی دانشگاه شهید چمران اهواز

3 دانشجوی کارشناسی ارشد دانشگاه شهید چمران اهواز

10.22034/ijissi.2024.2016724.1273

Abstract

In recent years, attempts have been made to put aside the hard chromium coating due to environmental damage of its plating baths. The Cr, Ni-Cr and Cr-Ni coatings produced in the baths contained Cr 3+ ions due to their low toxicity, are very good substitutes for the hard chromium coatings. In this study, using electroplating, Ni-Cr coatings were created and the effect of formic acid concentration as complexing agents were investigated. The electrodeposition mechanism of coatings was studied by cyclic voltammetry tests. The SEM and XRD methods were used for investigation the microstructure of the coatings. The pinch-on-disk and potentio-dynamic polarization tests were used for studding wear and corrosion behavior of coatings. The results of the cyclic voltammetry test showed that increasing the concentration of formic acid resulted in increasing deposition of chromium ion during electrodeposition. Increasing concentration of formic acid in bath to 30 g/l dramatically increased micro hardness of coatings to a values similar to that obtained for the conventional hard chromium coating. It was due to formation of chromium carbides during electrodeposition process as revealed at XRD patterns of coatings. In addition, in this case, chromium content of coating increases to 86 weight percent and the grain size of coatings reduced to 40 nm. The best corrosion and wear resistance of coatings obtained at 30 g/l formic acid in bath. It was due to high hardness and crack-free microstructure of the coatings.

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International Journal of Iron & Steel Society of Iran

Articles in Press, Accepted Manuscript
Available Online from 09 March 2024

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