Synthesis and surface characterization of boehmite and activated alumina coatings on FeCrAl sintered fibers

This study investigates the development of high-surface-area boehmite (γ-AlO(OH)) and activated alumina (γ-Al2O3) coatings on FeCrAl sintered fibers. The coatings were synthesized using colloidal aluminum oxide hydroxide (AlO(OH)) nanoparticles to increase the fibers' active surface area and enhance their performance as filtering media and catalyst substrates. Detailed methodologies for sample preparation, coating deposition, and material characterization are presented. The specific surface areas of the powders and coated fibers were determined using the Brunauer–Emmett–Teller (BET) method. In powder form, boehmite and activated alumina exhibited surface areas of 263 m2/g and 176 m2/g, respectively, after heat treatments at 300 °C and 500 °C for 2 h. Following deposition onto FeCrAl fibers, the coatings achieved surface areas of 134 m2/g for boehmite and 145 m2/g for activated alumina. Although the coated layers exhibited reduced surface areas compared to their powder forms, they significantly improved the surface characteristics of the FeCrAl substrates. This work introduces a novel coating approach, involving a thin layer of boehmite and activated alumina, on FeCrAl sintered fibers, achieving substantial surface area enhancement through controlled thermal processing. Comprehensive structural and surface characterization (TGA, XRD, XRF, BET, SEM, and EDS) established strong correlations among phase composition, morphology, and coating adhesion, revealing superior bonding for activated alumina. These innovations highlight the potential of the developed coatings to advance next-generation FeCrAl-based materials for applications in adsorption, filtration, and catalysis.