Lars Weisensel

Deflocculants for tape casting of TiO2 slurries

Abstract Five dispersants, polycondensed fatty acid, castor oil, phosphate ester, polyvinyl butyral (B79), polyvinyl butyral (B98) are used as dispersant. The dispersability of TiO 2 slurries is studied through ESA measurement, rheological characterization and FTIR test. ESA measurement shows that the adsorption of PVB79 and phosphate ester is of physical and chemical type, respectively. Rheology, TG–DTA and sedimentation measurements show that in the absence of binder, PVB79 is the best dispersant; after the addition of binder, phosphate ester is the best one. The adsorption of dispersants on powder surface is also characterized by FTIR. The dispersion and stability mechanism is discussed.

Binary solvent mixture for tape casting of TiO2 sheets

Abstract 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 plasticizer. The dispersability of TiO2 suspensions was characterized by rheological measurements and sedimentation tests. After tape casting, the properties of Green tapes were tested in term of density, surface roughness and strength. Results showed that azeotropic EtOH/MEK mixture is the effective solvent system for tape casting of TiO2 sheets. The TiO2 tapes served for multilayer ceramic/metal composite manufacturing.