Synthesis of Zirconia Balloons from Metal Alkoxide (Part 2)

--Size Reduction of Balloon and Balloon Structure--

Abstract

Zirconia balloons were molded from a formamide/benzene/formamide (F/B/F) emulsion. Balloons of several tens μm in size could be fabricated by dispersing 1.5mol·l^-1Zr(OC₄H₉ ⁿ)₄ benzene solution into formamide at 8000rpm. The size of the obtained zirconia balloon precursors ranged from 1μm to 50μm and its mean diameter was 20μm. Upon heat-treating at 1300°C zirconia balloon precursors transformed to zirconia balloons. The size distribution of heat-treated balloons was in the range between 1 and 45μm with a mean value of 10μm in diameter. The percentage of unflawed balloons was 91% after heat-treatment. The crust microstructure of the zirconia balloon changed with crust thickness. For thicknesses >1.5μm, the crust was constructed of about 0.3μm grains in diameter and had dense inner and outer surface layers. Pores were observed between these surface layers. For thicknesses between 0.3 and 0.9μm, the balloon crust was constructed by one to three 0.3μm grains in diameter. Decreasing crust thickness to less than 0.3μm, a single plate like grain was observed.