SURFACE-ANALYSIS OF SOL-GEL COATINGS ON GLASS BY SECONDARY NEUTRAL MASS-SPECTROMETRY

Secondary neutral mass spectrometry (SNMS) has been used to profile co atings of the systems SiO2 and 65SiO(2) . 20TiO(2) . 15ZrO(2) (STZ). T he coatings have been deposited on float glass and heat insulating gla ss by dip coating from alkoxide solutions. The microporous gel coating s have been densified by heat treatment. The SBM method (separate bomb ardment mode) has been applied to characterize the systems and the HFM method (high frequency mode) to check for matrix effects in the SBM d epth profiles. Both methods show sodium diffusion from the float glass substrate into the STZ coating and no significant sodium diffusion in to the SiO2 coating. Measurements of the coatings on the heat insulati ng glass indicate that the SnO2 interlayer acts as a diffusion barrier . The diffusion of sodium from the float glass substrate into the STZ coating during consolidation has been analyzed by SBM-SNMS. The sputte ring rate decreases with increasing consolidation. Due to large differ ences between sputtering rates of the substrate and of the microporous coatings, the calibration of sodium intensities from time to depth at the interface has not been possible. However, a correlation between t he final temperature of heal treatment and the depth of the Na2O deple tion in the substrate surface under the coating can be obtained.