Browsing by Author "Chao, Cheun-Guang"

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Anti-corrosion characteristics of polyimide/h-boron nitride composite films with different polymer configurations
(2014-12-15)
Huang, Yi-Chia
;
Lo, Teng-Yuan
;
Chao, Cheun-Guang
;
Whang, Wha-Tzong
;
材料科學與工程學系
Anti-corrosive polyimide/hexagonal boron nitride (PI/h-EN) composite films were prepared with different monomers to offer different polymer configurations: rigid and soft. In PI/h-BN composite films, different configurations of polymers show different crystallinity trends of the polymer matrix. In our study, the degree of crystallinity in rigid polymer decreases with the EN content; in flexible polymers it is independent of the BN content. It is worth noting that BN in different PI matrices can effectively enhance the protection of steel from corrosion. With a flexible PI matrix, the PI/h-BN coating exhibited better resistance to water vapor and better anti-corrosion. Only 5 wt.% of h-BN in the composite is enough to offer high anti-corrosion, a positive corrosion voltage. (C) 2014 Elsevier B.V. All rights reserved.
Mechanism of Aluminum Induced Lateral Crystallization of Amorphous Silicon
(2010)
Huang, Shih-Yang
;
Wang, Chuan-Chi
;
Lin, Chih-Lung
;
Tsai, Yu-Lin
;
Chao, Cheun-Guang
The aluminium-induced lateral crystallization (AILC) of amorphous silicon (a-Si) on a glass substrate has been investigated. By means of a photoresist-based process, Al islands (100 nm) were thermally evaporated using 15 V, 3.5 A, and 25 V, 5.6A on the a-Si layer (100 nm), which was deposited on a glass substrate. SEM examinations indicated that the Al islands exhibited smooth and crystalline-grain morphology. Annealing processes were carried out at 748 and 823 K for various times. After annealing, AILC could be clearly observed in the crystalline-grain sample, but not in the smooth sample. TEM analyses showed that the mechanism of AILC resulted from two layer exchange processes. First, the Al islands exchanged with the underlying a-Si layer vertically during AIC, and then the generation of Al particles accompanying AIC caused a lateral layer exchange with the remaining a-Si layer with further annealing. (C) 2010 The Japan Society of Applied Physics
Sputter deposition of multi-element nanoparticles as electrocatalysts for methanol oxidation
(2008-07-01)
Tsai, Chih-Fang
;
Wu, Pu-Wei
;
Lin, Pang
;
Chao, Cheun-Guang
;
Yeh, Kung-Yu
Fabrication of multi-element nanoparticles on noncatalyzed gas diffusion electrodes (GDEs) by radio frequency sputter deposition was reported. X-ray diffraction analysis of the as-deposited films indicated crystalline fee phases while energy dispersive X-ray spectroscope confirmed their composition as Pt(50)Fe(11)Co(10)Ni(11)Cu(10)Ag(8). Scanning electron microscopy images revealed nanoparticulate nodules growing on the carbon particles. Cyclic voltammetry (CV) was employed to analyze their methanol oxidation abilities for direct methanol fuel cells. The CV responses improved upon cycling and became stabilized after 70 cycles. The areas under the CV curves were proportional to the amount of nanoparticles deposited. In mass activities the GDE with 5 nm nanoparticles demonstrated the highest values of 400-600 mA/mg. In comparing with Pt and Pt(43)Ru(57), the Pt(43)Ru(57) exhibited the lowest onset potential with the highest mass activities. Our work presents preliminary information on the catalytic behaviors of multi-element nanoparticles which is likely to bring new directions in catalyst design.