Particularities of indoor atmospheric corrosion of steel inside electric boxes in the tropical climate of Tabasco, Mexico

摘要

Indoor corrosion inside electric boxes is important for the reliability of electric and electronic instruments. A parallel evaluation of indoor/outdoor atmospheric corrosion of steel, pollutants and meteorological parameters was made at two sites, i.e. a rural site and a coastal site of the Tabasco State, Mexico. Two exposure conditions were evaluated: outdoors and inside electric boxes. Very low levels of sulphur compounds have been observed at the two exposure sites and two exposure conditions. As expected, corrosion of steel in an open atmosphere is higher than indoors (electric boxes). The difference between corrosion outdoors and inside electric boxes is higher at the coastal site due to the influence of chloride deposition. Significant differences have been observed in the morphology of corrosion products formed on steel. The influence of sun radiation, rain, dew and fog causes the formation of more compact corrosion products. The influence of Time of Wetness outdoors is in some extent equivalent to the influence of relative humidity inside electric boxes. Commonly, chloride deposition is very low indoors, showing low influence on corrosion. However, in particular conditions of Tabasco coastal tropical climate, its role is significant indoors. Reliability of electric and electronic instruments could be affected.