新型炭材料
Chemical vapor deposition (CVD) is an effective way for the preparation of graphene with large area and high quality. In this review, the mechanism and characteristics of the four main preparation methods of graphene are briefly introduced, including micromechanical cleavage, chemical exfoliation, SiC epitaxial growth and CVD. The recent advances in the CVD growth of graphene and the related transfer techniques in terms of structure control, quality improvement and large area graphene synthesis were discussed. Other possible methods for the CVD growth of graphene were analyzed including the synthesis and nondestructive transfer of large area single crystalline graphene, graphene nanoribbons and graphene macrostructures.
关键词:
Graphene;Preparation;Chemical vapor deposition;Transfer;few-layer graphene;epitaxial graphene;large-area;carbon;films;surfaces;nickel;phase
Applied Physics Letters
We developed an ambient pressure chemical vapor deposition (CVD) for rapid growth of high-quality graphene films on Cu foils. The quality and growth rate of graphene films are dramatically increased with decreasing H(2) concentration. Without the presence of H(2), continuous graphene films are obtained with a mean sheet resistance of < 350 Omega/sq and light transmittance of 96.3% at 550 nm. Because of the ambient pressure, rapid growth rate, absence of H(2) and readily available Cu foils, this CVD process enables inexpensive and high-throughput growth of high-quality graphene films. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3512865]
关键词:
J.Koh
,
B.Kim
材料科学技术（英文）
We present a brief review about recent results regarding carbon nanotube (CNT)-based chemical and biomole-cular sensors. For the fabrication of CNT-based sensors, devices containing CNT channels between two metal electrodes are first fabricated usually via chemical vapor deposition (CVD) or “surface programmed assembly” method. Then, the CNT surfaces are often functionalized to enhance the selectivity of the sensors. Using this process, highly-sensitive CNT-based sensors can be fabricated for the selective detection of various chemical and biological molecules such as hydrogen, ammonia, carbon monoxide, chlorine gas, DNA, glucose, alcohol, and proteins.
关键词:
Chemical vapour deposition
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vapour
,
deposition
,
carbon
,
nanotu
Y. Chen
,
X. Chen
,
Q.F. Wang
金属学报(英文版)
The systematic chemical compositions including common C, Si, Mn, Al, and micro- alloying elements of Ti and Nb were designed for high volume fraction of retained austenite as much as possible. The thermo-cycle experiments were conducted by using Gleeble 2000 thermo-dynamic test machine for finding the appropriate composition. The experimental results showed that chemical composition had a significant effect on retained austenite, and the appropriate compositions were determined for commercial production of TRIP steels.
关键词:
carbon content
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null
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null
,
null
,
null
Anti-Corrosion Methods and Materials
Purpose - The objective of the present work was to study the influence of chemical compositions of five naphthenic acids (NAs) extracted from Liaohe crude oil on their corrosivity. Design/methodology/approach - Fourier-transform infrared spectrometry and electron impact mass spectrometry were used to characterize the chemical structures and compositions if five NAs. The corrosivities of the NAs were assessed by stagnant NA corrosion (NAC) tests. An attempt was made to identify any correlation between the chemical composition of the NAs and their corrosiveness. Findings - The acidic species in all five NA samples were saturated aliphatic and naphthenic acids and the amount of aromatic and unsaturated acids was negligible. A relationship between the carboxylic acid distribution and the molecular weight was obtained. Most of the carboxylic acids in five NAs contained 0-3 ring structures. NAs with lower molecular weight and fewer ring structures usually were more corrosive. Originality/value - The findings have important implications for assessing the corrosivity of acidic crude oils from various resources.
关键词:
acids;corrosion;mass spectrometry;oils;chromatography-mass spectrometry;erosion-corrosion;high-temperature;crude-oil;steels;q235
Dongping TAO
金属学报(英文版)
A novel molecular interaction chemical model (MICM) for silicate melts has been suggested based on statistical thermodynamics. It can simultaneously predict activities of all components in the CaO-FeO-SiO2 and CaO-Al2O3-SiO2 melts using only four binary parameters for each binary melt which can be determined by fitting activities of its two components. The results indicate that the predicted values of activity of FeO and SiO2 are in good agreement with the experimental data at 1823 K and 1873 K, and those of CaO, SiO2 and Al2O3 are in reasonable agreement with the graphical integration data of the Gibbs-Duhem equation. This shows that the model is effective in which the physical interaction plays a main role and the chemical one does the auxiliary function.
关键词:
Activity
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Prediction
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Oxide melts
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Silicates
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A novel model
SUN Shoujin WEI Yongliang LIU Min LI Minjun Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
China research associate
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The secondary reinforcement,crbon whiskers,may grow on the surface of parent rein- forcement,carbon fibres,by chemical vapour growth from acetylene using Fe salt as catalyzer.The optimal growing temperature is about 1000℃,and while the concentra- tion of catalytic solution is appropriate,the carbon whiskers may deposite uniformly and link each other on the parent carbon fibre surface.If the temperature or concentration is too high,the coarse clusters of carbon may deposite on the fibre surface.The mechanism of carbon whisker growth is believed that the carbon atoms in vapour phase dissolve in the Fe salt drops over fibres,then the solid carbon grains precipitate on the fibre surface.
关键词:
carbon whisker
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null
,
null
,
null
Construction and Building Materials
The corrosion resistance performance of the rebar quenched by a new chemical reagent FM in concrete containing chloride ions was evaluated comparing with bare rebar, water-cooled rebar and air-cooled rebar using electrochemical methods. Two different accelerated corrosion tests (14 cycles of dry/wet alternated corrosion tests and long-term immersion tests) were carried out to accelerate the corrosion process. EIS results of both accelerated corrosion tests showed the corrosion resistance performance of different rebar specimens could be sequenced from high to low as FM-cooled rebar, bare rebar, air-cooled rebar, and water-cooled rebar. It was observed that, after 14 cycles of accelerated corrosion tests, the corrosion degree of FM-cooled rebar is the slightest and most of the initial scale remains undamaged. This result proves that the corrosion resistance of the FM-cooled rebar is much better than the other three kinds of rebar. By using FM-cooling process, the corrosion resistance performance of rebar in concrete has been improved by optimizing the quality of the scale. (C) 2010 Elsevier Ltd. All rights reserved.
关键词:
Rebar;Surface state;EIS;Corrosion resistance;Concrete;reinforcing steel;passive film;neutral solution;iron;spectroscopy;bars
