Improvement in crystallization and tensile strength of 3Al2O3·B2O3·2SiO2 ceramic fibers by Fe3+ addition

3Al 2 O 3 ·B 2 O 3 ·2SiO 2 ceramic fibers containing 0.01–1.09 wt% Fe 2 O 3 were successfully fabricated using a sol-gel method by adding Fe 3+ . All fibers possessed good strength and morphologies, and the effects of Fe 3+ on the microstructure, crystallization kinetics , and tensile strength of fibers were investigated. Results showed that added Fe 3+ promoted the crystallization of Al 4 B 2 O 9 phase since crystallization temperature and activation energy both decreased as the amount of Fe 2 O 3 increased. In addition, the morphology of Al 4 B 2 O 9 grains changed from globular to rod-like. The lattice parameters of Al 4 B 2 O 9 phase in fibers increased when Fe 3+ was added. XPS results confirmed that Fe 3+ broke down alumina network to create non-bridged oxygen bonds (NBO) that influenced lattice structure and shapes of Al 4 B 2 O 9 crystals. The addition of Fe 3+ is useful for regulating the microstructure and strength of 3Al 2 O 3 ·B 2 O 3 ·2SiO 2 fibers, and the tensile strength reached a maximum value of 1.5 GPa at 0.27 wt% Fe 2 O 3 .