Influence of preoxidation on Fecralloy efficacy as a catalyst support

Abstract

The physiochemical transformations caused by thermal pre-oxidation of the surface of Fecralloy® foil, an integral component of metallic monolith catalysts, have been studied to assess their influence on coating adherence. The foil coupons were pre-oxidised at 950 oC for 0, 5, 10 and 30 h and the mass gain was found to fit a hyperbolic model. Measurements were made of surface topography and microstructure using laser profiling interferometry (LPI) and scanning electron microscopy (SEM), with chemical analysis being obtained from X-ray diffraction (XRD). The optimal surface roughness was obtained after 10 h of pre-oxidation, when the surface contained significant amounts of -alumina arranged as randomly oriented whiskers. Upon coating of the treated foil coupons with a γ-alumina slurry, the sample pre-oxidised for 10 hours gave the best performance in terms of coating loading (7.94 mass %) and adherence (< 10 mass % loss) based on a ultrasonic vibration test.

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