Corrosion in smoke, hydrocarbon and SO 2 polluted atmospheres—I. General behaviour of iron

Abstract

Iron foil specimens have been exposed for up to 145 h in a modified industrial atmosphere test chamber, to a control air-based environment at 298 K with a relative humidity of 85% and a CO 2 concentration of 5500 ppm. Additions of SO 2 (3.5 ppm), ethane, ethylene or acetylene (8 ppm) and smoke produced by burning kerosene (up to 560 μg m −3 average concentration) have been made singly and in appropriate combinations, so the separate and combined effects could be examined subsequently by weight change, metallography, SEM/EDX etc. The smoke aerosol was characterized by size and shape using TEM, and its influence on the conductivity and pH of water assessed by appropriate methods. The many results are analysed in terms of considerations such as sorption, catalytic activity at active complexes on smoke platelet surfaces and the interaction with moisture and free radical chain oxidation mechanisms, in an attempt to bridge the gap between simple observation and the clearly subtle chemical reactions which can control such atmospheric corrosion.