Fabrication and characterization of mullite whiskers reinforced Al2O3-SiC-C castables

• Published in: Journal of alloys and compounds Vol. 1005; p. 175931
• Main Authors: Li, Wenhao, Xu, Zhiyuan, Tang, Hongting, Li, Rong, Li, Jing, Ren, Baodong, Liu, Bangbang, Luo, Jingxuan, Mao, Xiaodong, Zhang, Shaowei, Zhen, Qiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2024
• Subjects: Al2O3-SiC-C castables; First-principles calculations; Mullite whiskers; Thermal shock resistance and oxidation resistance; First-principles calculations; Al2O3-SiC-C castables; Thermal shock resistance and oxidation resistance; Mullite whiskers
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.175931

As a refractory material used in the iron runner of blast furnaces, the thermal shock resistance and oxidation resistance of Al2O3-SiC-C (ASC) castables are important factors affecting their service performance and service life. In this study, mullite whiskers were introduced in to ASC castables by in-situ growth using AlF3 as catalysts to improving its performance. The catalyst addition amount and heat treatment time affect the phase composition, microstructure, and performance of castables were investigated. Combined with characterization and first-principles calculation, it is suggested that the mullite whiskers grow along the c-axis direction, and their growth mode conforms to a vapor-solid (V-S) mechanism. As expected, the in-situ growth mullite whiskers significantly improved performance of ASC castables, especially when 1.2 wt% AlF3 was added as catalyst. Compared to the samples without AlF3 additives, the thermal shock resistance (RSR = 82.26 %) and oxidation resistance (I = 27.75 %) increased by 50.04 % and 49.21 %, respectively. Mullite whiskers were dispersed in the material, improved the thermal shock resistance of the castables through whisker bridging. Meanwhile, the intertwining of the whiskers forms an interlocking structure that hinders the oxidation process of the castables. Mullite whiskers not only serves as a bridging role but also prevents the diffusion of oxygen into the interior, which provide a novel approach for strengthening castables. [Display omitted] •In situ growth of mullite whiskers in Al2O3-SiC-C castables by a simple one-step solid-state sintering method.•The diameter and length of whiskers are regulated by both heat treatment time and catalyst addition amount.•The whiskers interlace with each other to form an interlocking structure.•The formation of mullite whiskers significantly enhances the thermal shock resistance and oxidation resistance of material.