The coupling effect of fiber diameter and La2O3 addition in the thermal stability of alumina nanofibers

Alumina nanofibers have garnered significant attention in high-temperature applications due to their excellent mechanical properties and chemical stability. However, under high-temperature conditions, grain coarsening in alumina nanofibers can lead to structural degradation, resulting in a rapid decline in mechanical performance. To obtain alumina nanofibers with enhanced thermal stability, samples were fabricated via electrospinning combined with the sol-gel method. The combined effects of fiber diameter and La 2 O 3 content on the microstructure and its evolution under high-temperature conditions were systematically investigated. The study revealed that the incorporation of 1-10 wt.% La 2 O 3 influenced the phase transformation and high-temperature grain growth behavior of alumina nanofibers. An appropriate amount of La 2 O 3 significantly enhanced the thermal stability of the fibers. For nanofibers with identical composition, a size effect on thermal stability was observed: smaller fiber diameters corresponded to higher stability. At elevated temperatures, fibers with diameters below 100 nm effectively inhibited abnormal grain growth. After being held at 1200 °C for 1 h, the nanofibers with 5 wt.% La 2 O 3 maintained a fine-grained microstructure without noticeable degradation.