Browsing by Author "Shi, Gia-Nan"

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A Single-Walled Carbon Nanotube Network Gas Sensing Device
(2011-08-01)
Wang, Li-Chun
;
Tang, Kea-Tiong
;
Teng, I-Ju
;
Kuo, Cheng-Tzu
;
Ho, Cheng-Long
The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT) networks. The SWCNT networks are synthesized on Al(2)O(3)-deposted SiO(2)/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD). The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO(2) and NH(3) vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO(2) and 24 ppm for NH(3).
The study of corrosion behavior of manganese-based conversion coating on LZ91 magnesium alloy: Effect of addition of pyrophosphate and cerium
(2020-07-01)
Jian, Shun-Yi
;
Tzeng, Yu-Chih
;
Ger, Ming-Der
;
Chang, Ko-Lun
;
Shi, Gia-Nan
A previous study by the authors reported that a Mn-Ce based conversion coating protects the surface of LZ91 magnesium alloy from corrosion. However, the acidic permanganate solution decomposes after several days of storage and this significantly affects the properties of the coating. To address this problem, this study presents a method to stabilize the acidic permanganate bath by adding pyrophosphate into the bath. The results show that all conversion coatings are amorphous and comprise two layers: a porous layer that contacts the substrate and a compact overlay. Coatings that are produced using a bath with Ce are more resistant to corrosion than those that are produced in a bath without Ce ions. Coatings that are stored in the Mn-Ce bath for 2 weeks are significantly less resistant to corrosion than coatings that are produced using an as-prepared Mn\\Ce bath. The salt spray test results of coatings that are produced using the as-prepared bath and stored for 2 weeks are found similar because the bath is rendered more stable by the addition of pyrophosphate. (C) 2020 The Authors. Published by Elsevier Ltd.