Reduction resistance of Al2O3–SiO2 refractories for hydrogen-based shaft furnaces

Abstract

Hydrogen-based shaft furnace direct reduction technology is a critical pathway for low-carbon metallurgy. However, there is a scarcity of research on reduction resistance and corrosion mechanisms of Al₂O₃–SiO₂ refractories for hydrogen-based shaft furnaces. This study integrated thermodynamic simulation with reduction testing under conditions mimicking industrial hydrogen-based shaft furnace parameters. The evolutions in mass, mechanical strength, phase composition, and microstructure of four representative Al₂O₃–SiO₂ refractories were systematically analyzed before and after exposure to H₂/CO reducing environments, and their corrosion mechanisms were investigated. The corrosion process involves gas penetration, diffusion, and chemical reactions. SiO₂ and Fe₂O₃ were identified as the primary reactive phases in these refractories. SiO₂ reacts with H₂ to produce gaseous SiO and water vapor, whereas Fe oxides catalyze CO decomposition, leading to carbon deposition. Progressive detachment of deposits and gaseous product escape causes structural damage, resulting in specimen mass loss and strength reduction. Elevated reduction pressure and CO presence in the atmosphere exacerbate refractory corrosion.