Abstract
Some problems in cleaning corroded cast iron and aluminium alloys for the quantitative removal of corrosion products are described. A number of cleaning methods have been investigated with particular reference to their effect on attack of the metal. Losses in weight of the metal often continued to increase as the period of immersion in the cleaning solution increased and these losses depended on the nature of the cleaning solution and on the surface condition of the metal. Hence the use of uncorroded specimens as ‘blanks’ can lead to misplaced confidence in the suitability of a particular method of cleaning. For cast iron, cathodic cleaning is recommended with particular attention given to the effects of graphitised surfaces. For aluminium alloys, repeated cleaning at room temperature in concentrated nitric acid saturated with chromium trioxide is recommended as a standard procedure, the true weight loss being determined by extrapolation to zero cleaning time.
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