Binary solvent mixture for tape casting of TiO2 sheets

Four azeotropic binary solvent mixtures based on ethanol/methyl ethyl ketone, ethanol/toluene, isopropanol/methyl ethyl ketone and isopropanol/toluene were studied for the dispersion of TiO2 powders. Two different polyvinyl butyral polymers (PVB79 and PVB98) were selected as dispersant and as binder and dibutyl phthalate (DBP) was used as plasticiser. The dispersability of TiO2 suspensions was characterised by rheological measurements and sedimentation tests. After tape casting, the properties of the green tapes were tested in terms of density, surface roughness and strength. Results showed that azeotropic EtOH/MEK mixture is the most effective solvent system for tape casting of TiO2 sheets. Multilayer laminates were formed with aluminium foils. After heat treatment, the laminates were converted into a Al2O3/TiAlx composite structure. 31 refs.