%0 Journal Article
%T Growth of Hierarchically Structured High-Surface Area Alumina on FeCrAl Alloy Wires
%A Chandni Rallan
%A Aaron Akah
%A Patrick Hill
%A Arthur Garforth
%J Indian Journal of Materials Science
%D 2013
%R 10.1155/2013/251495
%X The formation of metastable alumina phases due to the oxidation of commercial FeCrAl alloy wires (0.5£¿mm thickness) at various temperatures and time periods has been examined. Samples were isothermally oxidised in air using a thermogravimetric analyzer (TGA). The morphology of the oxidised samples was analyzed using an Electronic Scanning Electron Microscope (ESEM) and X-ray on the surface analysis was done using an Energy Dispersive X-Ray (EDX) analyzer. The technique of X-Ray Diffraction (XRD) was used to characterize the phase of the oxide growth. The entire study showed that it was possible to grow high-surface area gamma alumina on the FeCrAl alloy wire surfaces when isothermally oxidised above 800¡ãC over several hours. 1. Introduction Modern day car-exhaust systems use catalysts supported on ceramic monoliths. The last decade has seen a move towards metallic monoliths affording improved conversion and selectivity [1]. The use of catalysts supported on metal for packed bed catalytic reactions has been limited [2]. A structured catalyst with an alumina wash coat deposited on a highly conductive support, such as a FeCr alloy, has the potential to eliminate the heat transfer limitations in catalytic processes [1, 3¨C5]. An adherent alumina wash coat on metal supports remains a challenge both to ensure that the support is anchored when thermal cycling is inherent in the operation of fixed bed reactors and to ensure that sufficient active catalyst is available to maintain required conversions. The growth of transient metastable aluminas (¦È-, ¦Ã-) on foils when oxidised at temperatures of 800¡ãC¨C1000¡ãC for varied time periods has been reported [6¨C8]. During the phase transformation of the transient aluminas, there are particular oxidation parameters which result in the growth of a ¦Ã-Al2O3 layer which has properties of high-surface area and porosity. The structured morphology helps improve the adherence of a coating layer and also forms a base for synthesis of other supporting catalysts [9]. This paper aims to give a better understanding of the growth of the ¦Ã-Al2O3 layer by the controlled oxidation of FeCrAl alloy wires on a small scale (TGA) and laboratory scale (muffle furnace). Conditions are optimised for wires of 0.5£¿mm thickness with characterisation using ESEM and EDX. Further characterisation of the alumina phase by XRD was attempted. 2. Experimental 2.1. Material FeCrAl alloy wires of thickness 0.5£¿mm with a chemical composition of 72.8% Fe, 22% Cr, 5% Al, 0.1% Y, and 0.1% Si were used. The wires were commercially manufactured and supplied by
%U http://www.hindawi.com/journals/ijms/2013/251495/