The effect of sulfur dioxide on iron, copper and brass

Purpose – The purpose of this paper is to study, under laboratory conditions, the corrosive effect of sulfur dioxide (SO2) present in the atmosphere of urban and industrial areas on various construction materials. Design/methodology/approach – Iron, copper and brass metals were exposed to SO2 gas at different relative humidities that were obtained using analytical grade glycerol and water mixtures. The corrosion rates (mdd) of the samples were determined over 120?h using the weight?loss method under fixed relative humidity (rH) conditions. The change of galvanic current was measured as a function of exposure time over 196?h. Nyquist diagrams were obtained in 10-3?M Na2SO4 solutions with a pH value of 7.2, which was assumed to correspond to 100 percent rH conditions. Findings – The obtained data showed that the corrosion rate of the studied metals increased with increasing rH. The corrosion rate of the metals decreased with exposure time, due to accumulation of corrosion products over the surface of the metals. However, the surface films of corrosion products on the metal surfaces were not stable and the corrosion rate increased again with time when the surface film disappeared. Research limitations/implications – The atmospheric corrosion of the industrial materials is dependent upon the rH and SO2 concentration. The corrosive effect of SO2 present in the atmosphere of urban and industrial areas on various construction materials can be tested under laboratory conditions. Originality/value – The effects of SO2 and NH3 on the atmospheric corrosion of galvanized iron and the effect of rH on the atmospheric corrosion of defective organic coating materials were reported in literature. In this study, the corrosive effect of SO2 present in the atmosphere of urban and industrial areas on various construction materials (iron, copper and brass) under laboratory conditions was studied. © 2011, Emerald Group Publishing Limite