Browsing by Author "Kuo, Chin-Guo"

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A novel method of centrifugal processing for the synthesis of lead-bismuth eutectic alloy nanospheres and nanowires
(2007-03-01)
Kuo, Chin-Guo
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Chao, Chuen-Guang
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材料科學與工程學系
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Department of Materials Science and Engineering
In the present study, lead-bismuth (Pb-Bi) eutectic alloy nanospheres and nanowires were fabricated using a process based on centrifugal force. When various centrifugal forces were applied, nanospheres and nanowires were formed on/inside the highly ordered anodic aluminum oxide (AAO) templates. The X-ray diffraction spectrum showed that nanoscale wires were composed of Pb(7)Bi(3) and Bi phases. The scanning electron microscopy (SEM) images proved the formation of nanospheres and nanowires on/inside the alumna channel templates. During centrifugation, the repulsive force between the nanochannel and the alloy melt was calculated from the surface tension on the ultra-fine tube. The force applied to the melt of Pb-Bi inside the AAO was controlled by the centrifugal force.
Effect of ECAE on Microstructures and Mechanical Properties of Solution Heat Treated Mg-5(mass%) Sn Alloy
(2013-08-01)
Tsai, Hao-Jan
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Kuo, Chin-Guo
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Chao, Chuen-Guang
;
Liu, Tzeng-Feng
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材料科學與工程學系
The microstructures and mechanical properties of the Mg-5(mass%) Sn alloy subjected to a solution heat treatment (SHT) were investigated by using equal channel angular extrusion (ECAE). The average grain size was significantly refined from 147 mu m (as-cast) to 16 mu m by ECAE four passes. Further, the fine Mg2Sn particles were uniformly distributed in the matrix by dynamic precipitation after ECAE four passes. The yield strength (YS), ultimate tensile strength (UTS) and elongations also showed notable improvements at room temperature and high temperatures (100 and 200 degrees C) on account of the ECAE process. Further, the tensile strength and elongations were better than those of the ECAE without SHT alloy. Those results show that SHT is a useful way to enhance the effect of ECAE on the mechanical properties of Mg-5 (mass%) Sn alloy.
Fabrication of bismuth nanoballs using thermal oil reflow
(2008-11-01)
Kuo, Chin-Guo
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Chen, Chien-Chon
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Hsieh, Sheng-Jen
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Say, Wen C.
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應用化學系
Sub-micron-size bismuth (Bi) balls with diameters between 100 and 2000 nm were formed on an anodic aluminum oxide (AAO) template using thermal expansion and thermal oil reflow processes. After centrifugal force separation, 100 nm size Bi balls were obtained. In addition, the ball density was approximately 6 x 10(7)/cm(2) on an AAO surface. Because of their round shape, the contact angle of the Bi nanoballs on the AAO surface was large after hot oil reflow, making it easy to remove them using ultrasound and to separate different sizes of balls using centrifugal force. (C) 2008 The Ceramic society of Japan. All rights reserved.
Improved Performance for Dye-Sensitized Solar Cells Using a Compact TiO2 Layer Grown by Sputtering
(2014)
Chang, Hung-Chih
;
Twu, Ming-Jenq
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Hsu, Chun-Yao
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Hsu, Ray-Quen
;
Kuo, Chin-Guo
This work determines the effect of compact TiO2 layers that are deposited onto fluorine-doped tin oxide (FTO), to improve the performance of dye-sensitized solar cells (DSSC). A series of compact TiO2 layers are prepared using radio frequency (rf) reactive magnetron sputtering. The films are characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The results show that when the Ar/O-2/N-2 flow rates are 36 : 18 : 9, the photo-induced decomposition of methylene blue and photo-induced hydrophilicity are enhanced. After annealing at 450 degrees C in an atmosphere ambient for 30 min, the compact TiO2 layers exhibit higher optical transmittance. The XRD patterns for the TiO2 films for FTO/glass show a good crystalline structure and anatase (101) diffraction peaks, which demonstrate a higher crystallinity than the ITO/glass films. As a result of this increase in the short circuit photocurrent density, the open-circuit photovoltage, and the fill factor, the DSSC with the FTO/glass and Pt counter electrode demonstrates a solar conversion efficiency of 7.65%.
INVESTIGATING MICROSTRUCTURES AND HIGH TEMPERATURE SUPERPLASTICITY BEHAVIOR OF MG-5(MASS%) SN ALLOY BY USING EQUAL CHANNEL ANGULAR EXTRUSION
(2016-06)
Tsai, Hao-Jan
;
Kuo, Chin-Guo
;
Chao, Chuen-Guang
;
Liu, Tzeng-Feng
;
材料科學與工程學系
In this study, we investigated the microstructures and high temperature plasticity behaviour of an Mg-5(mass%) Sn alloy after equal channel angular extrusion (ECAE). These results show that the grain boundary of the as-cast Mg-5(mass%) Sn alloy contained continuous eutectic alpha-Mg + Mg2Sn precipitates. After an ECAE process, the average grain size decreased from 147 mu m to about 10 mu m and the continuous eutectic alpha-Mg + Mg2Sn particles were broken down, and those particles distributed uniformly. The maximum elongation was 550 % at high temperature 350 degrees C with strain rate of 1 x 10(-3) s(-1).
Method of manufacturing aluminum oxide film with arrayed nanometric pores
(2006-03-09)
Chao, Chuen-Guang
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Chen, Chien-Chon
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Chen, Jung-Hsuan
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Kuo, Chin-Guo
The present invention pertains to a method of manufacturing an aluminum oxide film with arrayed nanometric pores, wherein a commercial aluminum substrate is provided firstly; then the aluminum substrate is annealed and then electro-polished in order to have a mirror-like surface, and then anodized in order to form a aluminum oxide film with a plurality of nanometric pores, which are aligned in array, and then annealed in order that an oxidation reaction can happen thereon and generates oxide, which via self-diffusion, fills some of smaller pores with the pores size being uniformed; lastly a pore-widening is undertaken in order to increase the diameters of the pores. The present invention can accomplish the nanometric pores aligned in array and with an uniform pore diameter, and simultaneously have the advantages of simplified manufacturing process, easier operational control and reduced cost.