Browsing by Author "Tung, Kuo-Lun"

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Growth of zirconia and yttria-stabilized zirconia nanorod arrays assisted by phase transition
(2010)
Chen, Chih-Chiang
;
Cheng, Wei-Yun
;
Lu, Shih-Yuan
;
Lin, Yi-Feng
;
Hsu, Yung-Jung
Well-aligned, densely distributed ZrO(2) nanorod arrays were fabricated using a non-catalytic, template-free metal-organic chemical vapour deposition process at a reaction temperature of 1000 degrees C. The reaction temperature was found to play a key role in product morphology, with particle thin films obtained at 550 degrees C and nanorod arrays produced at 1000 degrees C. Increasing the reaction temperature led to the emergence of the medium-temperature tetragonal phase from the dominant low-temperature monoclinic phase, which is advantageous for anisotropic growth necessary for the nanorod formation. With the same deposition process, yttria-stabilized zirconia nanorod arrays of polycrystalline cubic phase were fabricated by co-feeding the dopant precursor, YCl(3), with the zirconia precursor, Zr(C(5)H(7)O(2))(4). The present work demonstrated the first example of monoclinic to tetragonal phase-transition assisted one-dimensional (1D) growth, and the concept can be extended to the formation of 1D nanostructures of materials possessing the monoclinic-tetragonal polymorphism.
Thermophoretic particle deposition efficiency in turbulent tube flow
(2008-05-01)
Lin, Jyh-Shyan
;
Tsai, Chuen-Jinn
;
Tung, Kuo-Lun
;
Chiang, Hann-Chyuan
;
環境工程研究所
This study investigated the thermophoretic particle deposition efficiency numerically. The critical trajectory was used to calculate thermophoretic particle deposition in turbulent tube flow. The numerical results obtained in turbulent flow regime in this study were validated by particle deposition efficiency measurements with monodisperse particles (particle diameter ranges from 0.038 to 0.498 mu m) in a tube (I. 18 m long, 0.43 cm i.d., stainless-steel tube). The theoretical predictions are found to fit the experimental data of Tsai et al. [Tsai, C. J., J. S. Lin, S. G. Aggarwal, and D. R. Chen, "Thermophoretic Deposition of Particles in Laminar and Turbulent Tube Flows," Aerosol Sci. Technol., 38, 131 (2004)] very well in turbulent flows. In addition, an empirical expression has been developed to predict the thermophoretic deposition efficiency in turbulent tube flow. (c) 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.