Structure and thermal expansion of multi-walled carbon nanotubes before and after high temperature treatment

2005 ◽  
Vol 38 (24) ◽  
pp. 4302-4307 ◽  
Author(s):  
F Y Wu ◽  
H M Cheng
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Expansion ◽  
High Temperature ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Before And After ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Purifying double-walled carbon nanotubes by vacuum high-temperature treatment

2007 ◽  
Vol 18 (17) ◽  
pp. 175704 ◽  
Author(s):  
Yanping Liu ◽  
Yao Wang ◽  
Yi Liu ◽  
Wenjun Li ◽  
Weiping Zhou ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Temperature ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

DESCRIPTION OF CHEMICALLY AND THERMALLY TREATED MULTI-WALLED CARBON NANOTUBES USING SEQUENTIAL DECOMPOSITION OF ADSORPTION ISOTHERMS

2016 ◽  
Vol 23 (04) ◽  
pp. 1650025
Author(s):  
ALBERTO G. ALBESA ◽  
MATÍAS RAFTI ◽  
JOSÉ LUIS VICENTE
Keyword(s):  
Carbon Nanotubes ◽  
Arc Discharge ◽  
Temperature Treatment ◽  
Theoretical Description ◽  
Multistep Method ◽  
High Temperature Treatment ◽  
Acid Oxidation ◽  
Adsorption Mechanisms ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The effect of wet acid oxidation by means of sulfuric/nitric acid mixtures, and high-temperature treatment of commercial arc-discharge synthesized multi-walled carbon nanotubes (MWCNTs) was studied. In order to analyze the adsorption capacities of differently treated MWCNTs, we employed a multistep method that considers separately different pressure ranges (zones) on the experimentally obtained isotherms. The method is based on simple gas isotherm measurements (N2, CO2, CH4, etc.). Low pressure ranges can be described using Dubinin’s model, while high pressure regimes can be fitted using different models such as BET multilayer and Freundlich equations. This analysis allows to elucidate how different substrate treatments (chemical and thermal) can affect the adsorbate–adsorbent interactions; moreover, theoretical description of adsorbate–adsorbate interactions can be improved if a combination of adsorption mechanisms are used instead of a unique model. The results hereby presented also show that, while MWCNTs are a promising material for storage applications, gas separation applications should carefully consider the effect of wide nanotube size distribution present on samples after activation procedures.

Effect of Expanded Temperature on Microstructure of Carbon Nanotubes/Expanded Graphite Composites

2013 ◽  
Vol 716 ◽  
pp. 373-378
Author(s):  
Qian Zhang ◽  
Xin Bao Gao ◽  
Tian Peng Li
Keyword(s):  
Carbon Nanotubes ◽  
Composite Material ◽  
High Temperature ◽  
Carbon Nanotube ◽  
Physical Adsorption ◽  
Expanded Graphite ◽  
Graphite Flake ◽  
Graphite Composite ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Carbon nanotube/expanded graphite composite material was prepared by expanding the mixture of multi-walled carbon nanotubes and expansible graphite under the condition of high temperature. The microstructure and composition was studied by using SEM and XRD. The study shows that the tubular structure of carbon nanotubes in the composite material is changed by high temperature expanding process, and the microstructure is different with different expanding temperature. When the expanding temperature was 900°C, carbon nanotubes transformed, then attached to the surface of expanded graphite flake, so carbon nanotubes and expanding graphite combined strongly; globular carbon nanotubes attached to the surface of expanded graphite flake at the temperature of 700°C, both were combined much more strongly; carbon nanotubes retained the tube structure at the temperature of 500°C, combination was looser due to the simple physical adsorption. The result shows that the choice of expanding temperature has an important effect on microstructure of carbon nanotube/expanded graphite composite material.

scholarly journals High-temperature axial stress evolution mechanism of polyacrylonitrile-based carbon fiber

2020 ◽  
Vol 15 ◽  
pp. 155892502094885
Author(s):  
Yu Wang ◽  
Lian-Wei Ye ◽  
Ru-yu Ruan ◽  
Ai-Jun Gao ◽  
Yuan-Jian Tong
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Carbon Fiber ◽  
Graphite Furnace ◽  
Axial Stress ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Stress Evolution ◽  
Carbon Structure ◽  
The Difference

Temperature and stretching are important factors in the high-temperature treatment of carbon fiber. The axial stress during carbon-fiber high-temperature treatment affects its ability to stretch. The high-temperature axial stress evolution mechanism of polyacrylonitrile-based carbon fiber was studied through in situ tension tests, Raman spectroscopy, X-ray diffractometry, elemental analysis, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, thermal expansion coefficient tests, and density methods. The high-temperature axial stress evolution of polyacrylonitrile-based carbon fiber involved three stages: rapid increase, rapid decrease, and relaxation. The highest stress and relaxation temperatures of the polyacrylonitrile-based carbon fiber were 1600°C and 1950°C, respectively. The main factors that affected the fiber axial stress included carbon-structure rearrangement and the effect of thermal expansion and cold shrinkage on fiber length. During the first stage ( T < 1600°C), carbon-structure rearrangement after nitrogen atom removal increased the fiber axial stress. In the second stage (1600 ⩽  T ⩽ 1950°C), the difference in the thermal expansion of fibers that entered the graphite furnace and the cold shrinkage of fibers that exited the graphite furnace increased gradually, which resulted in a decrease in fiber axial stress by up to 1950°C, where the fiber relaxed and the third stage ( T > 1950°C) began. The difference between expansion and shrinkage increased significantly, which increased fiber relaxation. Carbon fibers with fewer nitrogen atoms and more regular structures had a lower axial stress during high-temperature treatment, but the trend and characteristic temperature remained unchanged. The corresponding fiber high-temperature maximum stretching ratio and axial stress showed opposite trends below 1950°C. The ability to stretch the carbon fiber increased above 1950°C, which differed from the axial stress relaxation.

Purification of Multi-Walled Carbon Nanotubes Grown by Thermal CVD on Fe-Based Catalyst

2006 ◽  
Vol 48 ◽  
pp. 50-54 ◽  
Author(s):  
Th. Dikonimos Makris ◽  
L. Giorgi ◽  
R. Giorgi ◽  
Nicola Lisi ◽  
Elena Salernitano ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Catalyst Support ◽  
Secondary Phase ◽  
Metal Catalyst ◽  
Purification Method ◽  
Thermal Cvd ◽  
Aluminum Ions ◽  
Before And After ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Aiming at the purpose of using carbon nanotubes as secondary phase in composite materials, removal of metal catalyst, catalyst support and amorphous carbon is crucial to make the most of the required properties. A purification method was developed to remove the metal catalyst from multi-walled nanotubes grown by thermal CVD. A nanosized Fe-based catalyst, prepared by coprecipitation of iron and aluminum ions, followed by solid state reaction, was used to catalyze the growth. Carbon nanotubes were subjected to acid purification and a comparison between nitric acid and a mixture of nitric and hydrochloric acid for the removal of Fe and Fe oxides is provided. Morphological and spectroscopic analyses of the materials were performed, both before and after the purification processes.

Comparative study of electrochemical capacitance of multi-walled carbon nanotubes before and after chopping

2010 ◽  
Vol 257 (2) ◽  
pp. 440-445 ◽  
Author(s):  
Changzhou Yuan ◽  
Laifa Shen ◽  
Diankai Li ◽  
Fang Zhang ◽  
Xiangjun Lu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Comparative Study ◽  
Electrochemical Capacitance ◽  
Before And After ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Influences of High Temperature Treatment of C/C on the Mechanical Properties of C/C-SiC Composites

2015 ◽  
Vol 816 ◽  
pp. 78-83
Author(s):  
Dong Lin ◽  
Jing Wang ◽  
Chang Rui Zhang ◽  
Ying Bin Cao ◽  
Rong Jun Liu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
High Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Sic Composites

C/C-SiC composite as low expansion material for space opto-mechanical structures was prepared by gaseous silicon infiltration after high temperature treatment (HTT) on C/C. 2000°C and 2400°C were selected as the treatment temperatures for C/C to study the influences on the properties of C/C-SiC composite. The graphitization level of amorphous C in C/C was improved by HTT. The porosity of C/C increased from 32.88% to 34.25% (2000°C) and 41.06% (2400°C) respectively. In addition, a higher HTT temperature led to a higher density of C/C-SiC composite and a lower SiC content. Furthermore, the mechanical properties and coefficient of thermal expansion (CTE) of the composite decreased as the temperature increased. After 2000°C HTT, the CTE of C/C-SiC composite decreased to-0.055×10-6·K-1 and the mechanical properties (218 MPa) could meet the application demand at the same time.

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