Aqueous Tape Casting of Barium Titanate Powders

Abstract

As more effort has focused on improving and miniaturizing electronic components, the demands for fabrication of thinner barium titanate (BaTiO3) films has accelerated within the ceramics industry. A key to successful in a fabrication of thinner films is dependent on the control of interparticle forces between colloidal ceramic particles dispersed in aqueous suspending media. In this presentation, various processing parameters affecting aqueous BaTiO3 tape casting were investigated in order to fabricate homogeneous green tapes by controlling interparticle forces between colloidal BaTiO3 particles. In particular, the physicochemical effects of individual slurry additives on the dispersion of BaTiO3 particles were examined in terms of mutual interactions between slurry additives. The dispersion properties of aqueous BaTiO3 suspensions were characterized by electrokinetic sonic amplitude(ESA), acoustosizer, polymer adsorption and rheological measurements. The role of electroacoustic analysis in tape casting will be given both for a characterization and process control applications. Some issues which will be considered include measurements in solids loading concentrations, background electrolyte contributions, and particle shape and size distribution effects. The adsorption characteristics and electrokinetic behavior of BaTiO3 suspensions were correlated with the dispersion stability of BaTiO3 particles suspended in aqueous media. The aging kinetics of BaTiO3 particles in aqueous systems was monitored by in-situ electroacoustic spectrometry by measuring simultaneously both electric potential and agglomerate size of BaTiO3 particles. Green tapes produced by aqueous tape casting were evaluated in terms of particle packing characteristics, lamination performance, and binder burnout. Attempts were made to draw a correlation between green tape characteristics and the slurry characteristics.