Washcoat Deposition of Ni- and Co-ZrO2 Low Surface Area Powders onto Ceramic Open-Cell Foams: Influence of Slurry Formulation and Rheology

摘要

Abstract: The effect of formulations and procedures to deposit thin active layers based onudlow surface area powders on complex geometry substrates (open-cell foams) wasudexperimentally assessed. An acid-free liquid medium based on water, glycerol, and polyvinyludalcohol was used for powder dispersion, while a dip-coating technique was chosen forudwashcoat deposition on 30 PPI ceramic open-cell foams. The rheological behavior wasudexplained on the bases of both porosity and actual powder density. It was proved that the useudof multiple dippings fulfills flexibility requirements for washcoat load management. Multipleuddepositions with intermediate flash drying steps at 350 °C were carried out. Washcoat loadsudin the 2.5 to 22 wt. % range were obtained. Pore clogging was seldom observed in a limitedudextent in samples with high loading (>20 wt. %). Adhesion, evaluated by means ofudaccelerated stress test in ultrasound bath, pointed out good results of all the deposited layers.