Corrosion behavior and mechanism of refractory linings in high-hydrogen zone of hydrogen-based shaft furnace

To evaluate the service stability of refractory linings in the high-hydrogen zone of hydrogen-based shaft furnace under strong reducing atmosphere, and clarify the response laws of phase, microstructure and properties of different materials under high H₂ partial pressure, Fluent simulation was first used to calculate the furnace-wall temperature, pressure, and gas-composition distributions. The middle-lower part of the reduction section and the region near reducing-gas inlet were identified as key locations with high temperature and high H₂ partial pressure, and were taken as the basis for the 930 ℃ H₂ reduction experiment. Grade I high-alumina brick, Grade Ⅱ high-alumina brick, corundum-SiC microporous brick, Sialon-corundum brick, and Si₃N₄-SiC brick were selected as the research objects. The samples were held in H₂ at 930 ℃ for 5, 10, 15, 20, 25 h. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, mass change, bulk density, apparent porosity, and cold compressive strength tests were used to investigate the evolution of phase structure and macroscopic properties. The results show that the Al₂O₃ skeleton phase remains stable under the experimental conditions, whereas sensitive components such as SiO₂, Fe₂O₃, and TiO₂ are more likely to participate in reduction reactions or structural rearrangement. After 25 h, the mass change rates of the five materials are -0.318%, -0.477%, +0.063%, -0.044%, and -0.262%, respectively. Among them, Grade II high-alumina brick exhibits the largest mass loss, indicating that higher contents of SiO₂ and Fe₂O₃ weaken its stability in a high-H₂ atmosphere. The corundum-SiC microporous brick shows the smallest mass change, together with increased bulk density and decreased apparent porosity, indicating good structural retention and resistance to H₂ penetration. Comprehensive analysis indicates that corrosion of lining materials in the high-H₂ zone can be described as a coupled process involving H₂ penetration into the material through open pores and microcracks, reduction or reconstruction of active components, pore-network evolution, and mechanical-property response. The corrosion resistance is mainly controlled by the thermodynamic stability of components, pore connectivity, and bonding-phase evolution. This study provides a reference for the selection and optimized design of refractory linings in the high-H₂ zone of hydrogen-based shaft furnaces.