Chemical corrosion in cast iron in soil-water medium

Grey cast iron metal strips were allowed to rust in varying compositions of soil-water media under the controlled environment. The process of corrosion was monitored by non-electrochemical method. Assessment of the extent of corrosion was carried out, both visually and by the method of weight loss coupons. It was found that a 80:20 weight:volume percent (w/v%) composition caused the most severe case of corrosion over a period of seven days. It was also observed that the corrosion in cast iron obeyed the relation, D = ktn [10]. The value of 'n' increased as corrosion became more severe. Gravimetric analysis and evidence from the Scanning Electron Microscopy (SEM) proved that gamma-FeOOH was one of the intermediates of corrosion in grey cast iron in soil-water media. An attempt has also been made to propose a mechanism for the corrosion in cast iron strips in soil-water media. It was found to be consistent with the one proposed by McEnaney and Smith [11].