SYNERGISTIC EFFECT OF CHLORIDE AND SULPHUR-BEARING POLLUTANT IN ATMOSPHERIC CORSOSION OF MILD STEEL

Immersion-wet-dry combined cyclic test was applied to study the synergistic effect of chloride and sulphur-bearing pollutant in atmospheric corrosion of mild steel. The experimental data were analysed and could be formulated by W = K. tn. Morphology of rust was observed by SEM and elemental distribution in rust was analysed by XPS. Results showed that the interaction between Cl- and HSO3 was rather complicated. At the beginning of corrosion, round blisters appeared on the rust and elemental contents inside and outside the blister were different. Synergistic effect of Cl- and HSO3 was significant. As corrosion went cn, the blisters dissapeared, the rust became compact, and the synergistic effect diminished.A mechanism for the synergistic effect was suggested.