Thick titania films were prepared by the modified electrophoretic sol-gel deposition method. The titania par ticles prepared by the sol-gel method were hydrothermally treated at 250 under 5MPa and then calcined at 600 in air. The particles crystallized by the hydrothermal treatment showed no aggregation during the calcination and were easily re-dispersed in a mixture of ethanol and water to form stable titania sol. Thick titania films of ca. 20m in thickness were obtained on stainless steel sheets by electrophoretic deposition of the sol.

Abstract. Monodispersed silica particles up to ca. 1.2/zm in diameter were prepared by hydrolysis of tetraethoxysilane in the presence of sodium dodecyl sulfate (SDS). The particle size was increased with an increase of SDS added. The geometrical standard deviation of the particles was decreased with an increase of SDS. In the earlier reaction stage, double spherical particles by the coalescence of the particles were frequently observed when large amounts of SDS were added. Particle size was gradually increased after the coalescence occurred and spherical particles were finally obtained. The results ofNielsen's chronomal analysis suggest that the polynuclear layer growth took place after the coalescence of the particles in the presence of larger amount of SDS.

Thick silica films were prepared on a stainless steel sheet by the electrophoretic sod; gel deposition method in the presence of sodium dodecyl sulfate (SDS). Elec trophoretic deposition was carried out for the silica sols prepared from tetraethoxysilane under the basic conditions. SDS was added as a dispersant in sol prepa ration. While deposited films were peeled off during drying process in the absence of SDS, thick films were prepared in the presence of SDS; the maximum thick ness of the films was about 20pm at an applied voltage of 30V and an SDS content of 0.05 mass%.