Sandblasting: the only way to eliminate rust?

摘要

The aim of the present work was to compare the performance of two coating systems applied on steel specimens. The first of them demands sandblasting pretreatment of the metal surface while the second one, which does not need it, leads to rusttransformation. These systems were examined in three corrosive environments i.e. a geothermal fluid of low enthalpy, a 3.5 wt per cent NaCl solution and a 5wt per cent NaCl in a salt spray cabinet. The anticorrosive capability of the two coating systemswas evaluated at predetermined exposure times by mass loss measurements of the steel substrate, by potentiodynamic polarization curves and by the half-cell potential time evolution. Visual examination of the degree of rusting and blistering was alsocarried out. The results indicate that both coating systems exhibit almost similar protective behavior under the same conditions of pretreatment. In all cases, the corrosion rate increases with the increase of the surface roughness.