CRACK-FREE POROUS YSZ MEMBRANE VIA CONTROLLED SYNTHESIS OF ZIRCONIA SOL

Sol-gel processing is one of the most powerful tool to synthesize inor ganic thin membranes, Several membranes, such as alumina, silica, tita nia, etc., have been prepared so far. The key in the sol-gel process i s how to conquer cracking in the drying stage. We approach this proble m in view of the control of sol-gel chemistry. The particulate zirconi a sol is a useful precursor to synthesize nanostructured yttria stabil ized zirconia (YSZ) at low temperature, but we could not prepare a cra ck-free film on a porous support due to its mechanical fragileness. Po lymeric sol containing linear chains of zirconium and oxygen was synth esized via controlled hydrolysis and condensation of zirconium n-butox ide using triethanolamine (TEA, 2,2',2 ''-nitrilotriethanol) as a chel ating agent. Polymeric sol is useful to remove cracking, but the film formation property on a porous support is so poor since most of the so l is sucked into the support and no gel layer is formed on the top. By mixing two sols, we successfully balance the film formation property and the mechanical strength to cracking. Thus, crack-free porous YSZ t hin membrane with a few-tens of nanometers pores are successfully prep ared. The nanostructure is still stable after the post-calcination at 1173 K.