To the problems of the function and the spreading of sulphate nests in the layer of corrosion products on steel

Abstract

The formation and propagation of sulphate nests in the corrosion products formed during atmospheric corrosion of steel is controlled to a large extend by the osmotic pressure within these nests. The same importance can be attributed to the composition of the FeOOH containing film covering the nests; as the FeOOH content increases the elasticity of the film is increased, too, so that the membrane is able to remain intact, i.e. without cracking even at increasing osmotic pressures in the nest. This behaviour improves the resistance of steel to atmospheric corrosion. These conditions are very important in particular with periodic wetting regimes. This mechanism also explains the effect of silicon which is incorporated in amorphous form in the corrosion products and thus improves the elasticity of the corrosion product membrane.

Atmospheric corrosion of mild steel. Part I - Rural and urban atmospheres

“…Among the main conclusions of this part of the MICAT project, the following can be listed: ± S 0 P 0 rural atmospheres, with very low chloride and SO 2 pollution, showed significantly different times of wetness (TOW) and environmental characteristics, such as soil particulate pollution and background pollution. As a consequence of these differences, a relatively wide range of steel corrosion rates could be observed, from 1.4 to 28.2 lm Á y À1 , after 1 year of exposure; ± the corrosivity categories determined from meteorological data were relatively higher than those determined from steel corrosion rates, both evaluated according to ISO standards; ± the steel corrosion product layers which were formed, constituted by lepidocrocite or lepidocrocite and goethite, showed increasing protectiveness, as is demonstrated by the increase in the corrosion rate decay with exposure time.…”

2005 F.N. Speller Award Lecture:Atmospheric Corrosion—Research, Testing, and Standardization

“…The work of Czech scientists represented important progress in the understanding of atmospheric corrosion in the 1960s and 70s (Barton, Beranek, Knotkova-Cermakova). [1][2][3][4] Czech corrosion engineers are still members of the leading international groups working in this fi eld. The present publication offers selected results of international and national cooperation intended for engineering application.…”