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|標題:||Effects of deposition parameters on characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition||作者:||Shiue, S.T.
|關鍵字:||Thermal chemical vapor deposition;Carbon coating;Optical fiber;Microstructure;induced stress voids;thin-films;amorphous-carbon;cvd carbon;diamond;films;pyrocarbon;temperature;chemistry;kinetics;methane||Project:||Surface & Coatings Technology||期刊/報告no：:||Surface & Coatings Technology, Volume 205, Issue 3, Page(s) 780-786.||摘要:||
The effects of deposition parameters on characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition are investigated. The deposition parameters are selected as follows. The CH(4)/(CH(4) + N(2)) ratio is in the range between 20% and 100%; the temperature is set from 1173 to 1248 K; the working pressure is arranged between 50 and 100 kPa, and the residence time is ranging from 1.47 to 7.37 s. The deposition rate, microstructure, and electrical resistivity of carbon coatings are measured. The low-temperature surface morphology of carbon-coated optical fibers is elucidated. Experimental results indicate that the deposition rate increases with increasing the CH(4)/(CH(4) + N(2)) ratio, deposition temperature, working pressure, and residence time. The activation energy (= 456 kJ/mol) of carbon deposition from methane was shown to correlate to the activation energy of methane dissociation. The deposition rate is proportional to about first-order of partial pressure of methane, and thus, the deposition process is mainly controlled by the process to create mono-carbon species in the carbon film. As the deposition rate increases, the size and number of particles on the carbon coating surface and electrical resistivity of carbon coatings increase, while the ordered degree, nano-crystallite size, and sp(2) carbon atoms of the carbon coatings decrease. Additionally, the low-temperature surface morphology of carbon coatings shows that as the carbon coating thickness is large enough to sustain the thermal loading, decreasing the deposition rate is good for producing hermetic optical fiber coatings. (C) 2010 Elsevier B.V. All rights reserved.
|Appears in Collections:||材料科學與工程學系|
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