Improving the green mechanical strength and thermal shock resistance of colloidal silica‐bonded castables using La2O3

Abstract Improving the green mechanical strength of colloidal silica‐bonded corundum castables is essential to their widespread utility. The effects of varying contents (0–2 wt%) of La 2 O 3 on the green mechanical strength of colloidal silica‐bonded corundum castables were investigated. The findings demonstrate that La 2 O 3 has a positive impact on the green mechanical strength of colloidal silica‐bonded castables. The colloidal silica‐bonded corundum castable containing 2 wt% La 2 O 3 exhibits higher green mechanical strength than the cement‐bonded corundum castable. Additionally, the castable shows excellent construction performance. The basic properties of La 2 O 3 and La(OH) 3 facilitate the absorption of H + from the surface of colloidal silica to form more siloxane bonds and speed up gelation. Fourier transform infrared spectroscopy and X‐ray fluorescence spectroscopy analyses indicate that La 3+ ions participate in the condensation of –Si–OH and bond the broken Si–O bonds to create Si–O–La chemical bonds. La 3+ ions bridge the colloidal silica particles, leading to stable three‐dimensional network structures that result in an increased green mechanical strength of the castables. The water consumption during the hydration reaction expedites gelation, further contributing to the enhancement of the green mechanical strength of the corundum castables. Given its wide sources and stable performance, La 2 O 3 can be considered an efficient setting agent with the potential for extensive industrial application.