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

Abstract 3Al2O3·B2O3·2SiO2 ceramic fibers containing 0.01–1.09 wt% Fe2O3 were successfully fabricated using a sol-gel method by adding Fe3+. All fibers possessed good strength and morphologies, and the effects of Fe3+ on the microstructure, crystallization kinetics, and tensile strength of fibers were investigated. Results showed that added Fe3+ promoted the crystallization of Al4B2O9 phase since crystallization temperature and activation energy both decreased as the amount of Fe2O3 increased. In addition, the morphology of Al4B2O9 grains changed from globular to rod-like. The lattice parameters of Al4B2O9 phase in fibers increased when Fe3+ was added. XPS results confirmed that Fe3+ broke down alumina network to create non-bridged oxygen bonds (NBO) that influenced lattice structure and shapes of Al4B2O9 crystals. The addition of Fe3+ is useful for regulating the microstructure and strength of 3Al2O3·B2O3·2SiO2 fibers, and the tensile strength reached a maximum value of 1.5 GPa at 0.27 wt% Fe2O3.