Title: Multilayer Zn-Ni-Al₂O₃ coatings for corrosion protection

Authors: Yathish Ullal; A. Chitharanjan Hegde

Addresses: Department of Chemistry, Electrochemistry Research Laboratory, National Institute of Technology Karnataka, Surathkal, Srinivasnagar-575025, India ' Department of Chemistry, Electrochemistry Research Laboratory, National Institute of Technology Karnataka, Surathkal, Srinivasnagar-575025, India

Abstract: The paper reports the development of composite coatings of Zn-Ni-Al₂O₃ by composition modulated multilayer (CMM) technique using m-aminophenol and gelatin as additives. The bath constituents and deposition parameters were optimised by conventional method. The role of gelatin and m-aminophenol in the bath was analysed by cyclic voltammetry (CV) study. Corrosion performance of the monolayer coatings was enhanced further by multilayer technique. The modulation in composition was effected by pulsing the DC in square-wave patterns. The coatings configurations were optimised for peak performance of the coatings against corrosion. It was found that corrosion resistance of CMM coatings increased with number of layers up to certain optimal numbers, and then decreased. Incorporation of Al₂O₃ particles into metal matrix was confirmed by EDAX. Formation of layered coating and their phase structures were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) study. Reasons responsible for better corrosion resistance of CMM composite coatings are analysed and results are discussed.

Keywords: multilayer coatings; Zn-Ni-Al2O3; corrosion protection; EDS; X-ray diffraction; XRD; scanning electron microscopy; SEM; nanotechnology; nanoparticles; zinc; nickel; aluminium oxide; alumina.

DOI: 10.1504/IJMATEI.2014.064282

International Journal of Materials Engineering Innovation, 2014 Vol.5 No.3, pp.247 - 260

Received: 28 Jan 2013
Accepted: 21 Sep 2013
Published online: 30 Aug 2014 *

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