PORE NARROWING AND FORMATION OF ULTRATHIN YTTRIA-STABILIZED ZIRCONIA LAYERS IN CERAMIC MEMBRANES BY CHEMICAL-VAPOR-DEPOSITION ELECTROCHEMICAL VAPOR-DEPOSITION

Chemical vapor deposition (CVD) and electrochemical vapor deposition ( EVD) have been applied to deposit yttria-stabilized-zirconia (YSZ) on porous ceramic media. The experimental results indicate that the locat ion of YSZ deposition can be varied from the surface of the substrates to the inside of the substrates by changing the CVD/EVD experimental conditions, i.e., the concentration ratio of the reactant vapors. The deposition width is strongly dependent on the deposition temperature u sed. The deposition of YSZ inside the pores resulted in pore narrowing and eventually pore closure, which was measured by using permporometr y. However, deposition of YSZ on top of porous ceramic substrates (out side the pores) did not result in a reduction of the average pore size . Ultrathin, dense YSZ layers on porous ceramic substrates can be obta ined by suppressing the EVD layer growth process after pore closure.