Effect of La₂O₃-Y₂O₃ Additives on Stability of Alumina Coat Layer on FeCrAl-Alloy Substrate

Abstract

Effect of La₂O₃-Y₂O₃ additives on coating and thermal stability of alumina layer on FeCrAl-alloy substrate was investigated. The stable alumina catalytic coat layer is required and its processing parameters are important in practical technology to fabricate automotive honeycomb-type catalytic converters. The two-step modification in La₂O₃-Y₂O₃-modified Al₂O₃ induced better slurry regarding with surface charge as colloid dispersion and rheological properties with lower viscosity and low stress under moderate shear rate condition. Surface Y₂O₃ controls zeta potential to high pH region so that alkaline solution can be applied to metal and alloy substrates. The newly modified Al₂O₃ coat layer can react with alumina interlayer grown on FeCrAl alloy surface. In conclusion, the optimal coating stability was attained with present La₂O₃-Y₂O₃ co-doped Al₂O₃.