Enhanced Green Mechanical Strength and Thermal Shock Resistance of Corundum Castables via Potassium Methyl Silicate–Modified Silica Sols

It is imperative to enhance the green mechanical strength and thermal shock resistance of silica sol‐bonded corundum castables to facilitate their large‐scale application. This study investigates the effects of potassium methyl silicate (PMS)–modified silica sol with different addition levels on the microstructure and properties of corundum castables. The results demonstrate that the green mechanical strength of corundum castables bonded with 1.5 wt% PMS‐modified silica sol reaches 10.4 MPa, which is more than twice that of pure silica sol‐bonded castables and even higher than that of conventional cement‐bonded castables. FT‐IR and XPS analyses reveal that the ─Si─OH groups generated by PMS hydrolysis participate in the formation of Si─O─Si bonds via dehydration condensation, promoting the condensation reaction of silica sol and accelerating the formation of stable Si─O─Si networks. The formation of a stable three‐dimensional Si─O─Si network effectively improves the green mechanical strength of silica sol‐bonded castables. Furthermore, after heat treatment at 1400°C, castables with added PMS show an increased amount of mullite phase and a lower apparent porosity, which is beneficial to improving their high‐temperature strength and thermal shock resistance. Featuring chemical stability and environmental friendliness, PMS exhibits great potential for large‐scale application in refractory castables.