MnO-mediated turing pattern corrosion of alumina refractory ceramic based on radical reactions: Transition mechanism from accelerator to inhibitor

• The dual functionality of MnO in influencing both the structural evolution of the slag and the generation of O 2 ·- was revealed. • Optimal MnO converts [AlO 6 ] and [SiO 4 ] to to Q n (Al), Q 0 (Si), and Q 1 (Si), thereby accelerating the corrosion. • The quenching effect of Mn 2+ /Mn 3+ on the O 2 ·- and the inhibition of Turing pattern corrosion were revealed. • This work offers a framework to optimize refractory design in steel refining. Alumina refractory ceramics are fundamental in refining Fe-Mn-Al-C low-density high-strength steel. In CaO-Al 2 O 3 -SiO 2 -based refining slags, severe interfacial free radical reactions produce Turing pattern corrosion that damages refractories. Given the crucial role of slag structure, the influence of MnO remains unclear. This study investigates the CaO-Al 2 O 3 -SiO 2 -MnO slag system to elucidate how MnO affects structural units (Al-O and Si-O networks) and the superoxide radicals (O 2 ·- ) involved in the process of Turing pattern corrosion. Results indicate that the effect of MnO on the conversion of [AlO 6 ] and [SiO 4 ] to reactive Q n (Al), Q 0 (Si), and Q 1 (Si) configurations, elevating non-bridging oxygen content, accelerating refractory dissolution, and intensifying corrosion. Conversely, with sufficient slag penetration, multivalent manganese (Mn 2+ /Mn 3+ ) in the penetration layer quenches O 2 ·- , mitigating interfacial reactions. This work reveals dual effect of MnO-mediated Turing pattern corrosion of alumina refractories based on radical reactions, and providing directions for optimizing refractory design in high-aluminum steel refining processes.