Papers by Author: Sung Goon Kang

Abstract: Lanthanum hydroxide and oxide were prepared by the precipitation method in an aqueous medium at room temperature. The precipitate was examined using thermal analysis, X-ray diffraction and Scanning Electron Microscopy to investigate the phase evaluation and the thermal transformation by decomposition. The as-precipitated powder from the precipitation method was hexagonal La(OH)3. The lanthanum hydroxide was decomposed to oxide in two-steps as La(OH)3 → LaOOH + H2O and 2LaOOH → La2O3 + H2O.

Abstract: Mechanical processing of nanocrystalline Y2O3 and transition alumina (AlOOH) was performed, using a Spex mixer mill under atmospheric conditions, to synthesize yttrium aluminum garnet (YAG, Y3Al5O12) powder at lower temperature. The reaction of nanocrystalline Y2O3 with AlOOH was activated by mechanical energy and use of fine instead of heat energy, leading to the direct formation of pure YAG without second phases at a lower temperature, 800°C, which is significantly lower than that required by the conventional solid-state reaction process.

Abstract: An optimum route to synthesize Al2O3-based composite powders with a homogeneous dispersion of carbon nanotubes (CNTs) was investigated. CNT/Metal/Al2O3 nanocomposite powders were fabricated by thermal chemical vapor deposition (CVD) over a metal catalyst homogeneously dispersed into an Al2O3 matrix by the means of chemical and selective reduction processes. The nanocomposite powders were densified by Pulse Electric Current Sintering (PECS). The experimental results show that the CNT/Metal/Al2O3 nanocomposites have unique electrical properties.