Hollow biomorphic Al2O3 fibers produced from sisal

Al2O3 fibers with a hollow morphology were produced by Al-vapor infiltration-reaction and subsequent oxidation from pyrolysed fibers of natural sisal. Following pyrolysis, the bio-fiber template was reacted with gaseous Al at 1,400 °C–1,600 °C in vacuum to form Al4C3. After an oxidation/sintering process at 1,550 °C, the biomorphic Al4C3 fibers were fully converted into Al2O3, maintaining the microstructural features of the native sisal. Phase and microstructural characterization during processing were evaluated by high temperature X-ray diffractometry and scanning electron microscopy, respectively. Thermo-analyses were performed in the Al4C3 samples in order to estimate the reactions and the weight change during the oxidation step.