Previous work from this laboratory the Instituto de QuõÂmica de SaÄo Carlos has shown the effectiveness of sol±gel-derived ceramic coatings for the protection of stainless steel against corrosion in H2SO4 [1±5] and NaCl solutions [6, 7]. The coatings used were ZrO2, SiO2, TiO2±SiO2 and Al2O3±SiO2. In all the cases, a large degree of protection was achieved with corrosion rates in H2SO4 diminishing by a factor of almost 6 for tests at room temperature [1±3] and 8.5 at 50 8C [4, 5]. Among the coatings, ZrO2 was most efficient and
