Influence of surface roughness on the corrosion behaviour of magnesium alloy

Walter, R., and Kannan, M. Bobby (2011) Influence of surface roughness on the corrosion behaviour of magnesium alloy. Materials & Design, 32 (4). pp. 2350-2354.

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Abstract

In this study, the influence of surface roughness on the passivation and pitting corrosion behaviour of AZ91 magnesium alloy in chloride-containing environment was examined using electrochemical techniques. Potentiodynamic polarisation and electrochemical impedance spectroscopy tests suggested that the passivation behaviour of the alloy was affected by increasing the surface roughness. Consequently, the corrosion current and the pitting tendency of the alloy also increased with increase in the surface roughness. Scanning electron micrographs of 24 h immersion test samples clearly revealed pitting corrosion in the highest surface roughness (Sa 430) alloy, whereas in the lowest surface roughness (Sa 80) alloy no evidence of pitting corrosion was observed. Interestingly, when the passivity of the alloy was disturbed by galvanostatically holding the sample at anodic current for 1 h, the alloy underwent high pitting corrosion irrespective of their surface roughness. Thus the study suggests that the surface roughness plays a critical role in the passivation behaviour of the alloy and hence the pitting tendency.

Item ID: 15919
Item Type: Article (Refereed Research - C1)
ISSN: 1873-4197
Date Deposited: 08 Jun 2011 23:49
FoR Codes: 09 ENGINEERING > 0912 Materials Engineering > 091207 Metals and Alloy Materials @ 100%
SEO Codes: 86 MANUFACTURING > 8611 Basic Metal Products (incl. Smelting, Rolling, Drawing and Extruding) > 861101 Basic Aluminium Products @ 100%
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