A comparative study on microstructure evolution and mechanical properties of two ceramic fiber fabrics: Effects of thermal treatment

Abstract Owing to their superior mechanical properties and low thermal conductivity, oxide ceramic fabrics (OCFs) containing an amorphous phase exhibit significant potential as thermal insulation material. However, the amorphous component is metastable, necessitating an investigation into the thermal stability of OCFs. Here, we comparatively investigated the microstructure and mechanical properties of two OCFs after thermal treatments. One OCF was composed of a ternary Al 2 O 3 ‐SiO 2 ‐B 2 O 3 glass, while the other binary OCF comprised Al 2 O 3 nanocrystallites embedded within a SiO 2 glass matrix. Results demonstrated that the crystallization of Al 4 B 2 O 9 occurred during the thermal treatment of the ternary OCFs, subsequently transforming into Al 18 B 4 O 33 . The SiO 2 persisted as a glass matrix up to 1300°C. In contrast, the binary OCF retained its microstructure up to 1100°C. After being treated at 1300°C, the binary OCF predominantly consisted of mullite micrograins, without the presence of amorphous phase. The flexural strength of the two OCFs decreased as the treatment temperature increased, and they lost their bendability due to the formation of a substantial number of crystallites. This study underscores the significant impacts of thermal treatment on the microstructure and mechanical properties of OCFs with amorphous component.