Franco Geotti-Bianchini

Preparation and characterization of Fe, Cr and Co oxide films on flat glass from gels

Abstract Iron, chromium and cobalt oxide films deposited on flat glass by pyrolysis of suitable compounds have been on the market for a long time. The purpose of the present investigation was to produce them by the gel method and to verify if a similar optical behaviour could be attained. One-component and multi-component coatings were obtained on a soda-lime glass; their oxide content was determined and their transmittance and reflectance were measured in the solar range. The sun-shielding performances obtained were generally lower than those provided by commercial sun-shielding glasses. A comparative analysis of the spectral behaviour in the visible range showed that the lower daylight-reflectances obtained for the dip coated plates can be explained mainly by the lower thicknesses obtained. However, the complex refractive indexes are also lower, possibly due to a less compact structure.

Infrared reflectance spectra of semi-transparent SiO2 rich films on silicate glasses: influence of the substrate and film thickness

The influence of the substrate and film thickness on the IR reflectance spectra of silicate glasses with silica rich surface films is demonstrated experimentally and with mathematical simulations. SiO2 films, both 0.3 and 0.6 μm thick, are sol–gel coated onto one metal and three glasses. The measured IRRS curves are definitely different, in agreement with predictions based on a Fresnel-type equation considering the optical constants of both the substrate and the surface layer, the film thickness and the wavelength. Mathematical simulations show that the IRRS curves are insensitive to the substrate only for SiO2 coatings with a thickness of several micrometers. These results show that the traditional interpretation of the IRRS spectra of leached and surface coated glasses, assuming that the incident beam is fully absorbed before reaching the film/substrate interface and therefore attributing all the observed bands to some species in the surface film, can be grossly approximated.

SAXS study of the micro-inhomogeneity of industrial soda lime silica glass.

Abstract The microstructure of a variety of industrial multicomponent soda lime glasses for container and glazing and of a lead alkali silicate glass for pressed tableware articles was analyzed using small angle X-ray scattering (SAXS). No inhomogeneity with size >0.5 nm was found in the industrial samples, while ternary soda lime glass samples with a suitable composition when heat treated developed a phase separation which SAXS detected without difficulty. The results obtained disprove earlier reports which attributed problems of rheology and strength affecting container production (‘bad workability’) to microstructure formation.