Corrosion Performance of Coating Thickness in Marine Environment

H. M. Hajar1, M.J. Suriani1, M.G.M. Sabri2, M.J. Ghazali3 and W. B. Wan Nik1*

1School of Ocean Engineering, 2School of Basic Sciences, Universiti Malaysia Terengganu, Malaysia, 21030 Kuala Terengganu, Malaysia. 3Faculty of Engineering and Built Environment, UniversitiKebangsaan Malaysia, Malaysia.

ABSTRACT: Traditionally, zinc has been used as metallic material to protect steel against atmospheric corrosion. The coatings are used for corrosion protection in a variety of industrial applications. This is due to its ability to provide cathodic protection to steel in all types of natural atmospheres. In the effort of determining the optimum coating thickness, a comparative study of the corrosion on mild steel coated by different thickness of zinc in marine environment was carried out. This paper presents the corrosion study of two marine environment which are immersion in seawater and also in salt spray splash environment. The aim of this study is to compare by experiment the corrosion rate of mild steel coated by different thickness of zinc under salt spray and also immersion. The corrosion measurement test was performed by weight loss measurement, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The morphological study on the surface degradation of the coated steel was performed by using scanning electron microscopy (SEM). The investigation on corrosion rate for the salt spray test shows higher loss percentage compared to seawater immersion. The bare mild steel recorded the highest corrosion rate compared to the other coated mild steel in both environments.

KEYWORDS: Marine environment; Mild steel; Potentiodynamic polarization; SEM, zinc coating

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