Preparation and characterization of dip-coated γ-alumina based ceramic materials on FeCrAl foils

Effects of metal surface pretreatment and slurry properties on coating γ-alumina based ceramic materials on metal surface were investigated. Surface of pre-oxidized FeCrAl foils and washcoat were characterized using XRD, SEM, ultrasonic vibration, thermal shock test and BET. It was found that oxidation layer on metal foil surface produced during pre-oxidation at 950 °C for 10 h exhibits an excellent compatibility with γ-alumina based washcoat. Experimental results show that adhesion of washcoat to FeCrAl foils depends on slurry particle sizes, pH and solid content. Wastcoat of desired properties were obtained with slurries having pH in the range 4.0–6.0, particle size distribution with 90% of particles (d90) less than 10.00 μm and a solid content about 35 wt.%. Addition of Ce0.68Zr0.32O2 solid solution powders into slurries improved γ-Al2O3-based washcoat adhesion to FeCrAl foils, and produced a more thermal stable washcoat which showed higher specific areas after thermal treatment in 10% steam-containing air at 1050 °C for 20 h.