The oriented growth behavior of α-Al2O3 grains in alumina-mullite biphasic fibers

• Published in: Journal of the European Ceramic Society Vol. 44; no. 1; pp. 319 - 327
• Main Authors: Wu, Chaozhong, Zhan, Lingjiao, Liu, Haotian, Wang, Juan, Liu, Wensheng, Yao, Shuwei, Ma, Yunzhu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2024
• Subjects: Alumina-mullite fibers; Grain boundary segregation; Lamellar α-Al2O3 grains; Microstructure; Oriented growth; Alumina-mullite fibers; Lamellar α-Al2O3 grains; Microstructure; Grain boundary segregation; Oriented growth
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2023.09.016

Understanding the mechanism of the oriented growth in multi-component alumina-based fibers and inhibiting its progression is crucial for enhancing their thermal stability. In this study, a novel diphasic fiber composed of lamellar α-Al2O3 and mosaic-like mullite grains was prepared. We discussed the oriented growth behavior of lamellar α-Al2O3 grains and the diffusion phenomenon of the Al element in SiO2 substrate under the combined addition of iron sol and La2O3, proposing a new mechanism for oriented growth in diphasic fibers. The diffusion of the Si element to the tips of alumina grains contributed to a significant increase in the mobility of non-basal planes, resulting in (0001) surface growth of α-Al2O3 grains. Furthermore, the La segregation at grain boundaries significantly impeded the oriented growth of α-Al2O3 grains, which was critical for improving the thermal stability of multiphase alumina-based fibers.