Some properties of protective sol–gel glass coatings on sintered stainless steels

Sol–gel SiO2 films are deposited onto sintered AISI 316 steel by dip-coating technique from TEOS (tetraethyl orthosilicate) precursor solution. Two different heating rates in the sintering step (800°C/2 h) were used, viz., 10 and 3°C/min. Analysis of the coatings were carried out by scanning electron microscopy and atomic force microscopy to determine the topographical features and the homogeneity of the films. Corrosion of coated and uncoated samples in H2SO4 was measured. Results indicate that the heating affects the homogeneity of a sintered film. A film prepared with a heating rate at 10°C/min is inhomogeneous when compared with a film prepared with a rate of 3°C/min; however the 3°C/min film had greater roughness (RMS) than the 10°C/min film (64.7 and 23.3 nm, respectively). For the corrosion data, a reduction in the passivation current, when compared with the non-coated steels is reported.