Fabrication of Al2O3 Microtubes Using Carbon Fibers and Al/ Al2O3 Mixed Powder in Solid-Vapor Reaction (SVR) Process
In this work, we report on the fabrication process of alumina (Al2O3) microtubes using carbon fibers and aluminum/alumina (Al/Al2O3) mixed powder via a solid-vapor (SV) reaction. Al and Al2O3 (α-Al2O3) were mixed in a 1:1 molar ratio, and heated to generate an AlO vapor. The carbon fibers were heat-treated in the pre-carburized Al2O3 crucible at 1400°C for 9h with a heating rate of 5°C/min in flowing argon (Ar) gas at 200 ml/min. Any carbon residues remaining in the core after the heat treatment at 1400°C were burned off by subsequent calcination at 700°C for 3 h in air. A post-heat treatment was conducted to convert the product to Al2O3. As a result, Al2O3 microtubes are successfully synthesized via the SV reaction between carbon fibers and Al/Al2O3 mixed powder. The TGA study shows that the AlO vapor is generated at temperatures above 750°C. As the calcination temperature increases, carbon residues and Al4C3 peaks disappear in XRD patterns. Al2O3 microtubes are synthesized at 1200°C, and show thinner wall thickness and undulating outer and inner surfaces arising from the partial decomposition of Al2O3 microtubes.
Hyungsun Kim, Junichi Hojo and Soo Wohn Lee
S. W. Myoung et al., "Fabrication of Al2O3 Microtubes Using Carbon Fibers and Al/ Al2O3 Mixed Powder in Solid-Vapor Reaction (SVR) Process", Materials Science Forum, Vols. 544-545, pp. 749-752, 2007