FUNDAMENTALS OF SOL-GEL DIP-COATING

During the process of dip-coating, the substrate is withdrawn from the sol at a constant rate. After several seconds, the process becomes st eady. The entrained film thins by evaporation of solvent and gravitati onal draining. Because the shape of the depositing film remains consta nt with respect to the reservoir surface, it is possible to use analyt ical methods such as ellipsometry and fluorescence spectroscopy to cha racterize the depositing film in situ. The microstructure and properti es of the film depend on the size and structure of the inorganic sol s pecies, the magnitude of the capillary pressure exerted during drying, and the relative rates of condensation and drying. By controlling the se parameters, it is possible to vary the porosity of the film over a wide range.