Measurements of Thermoelectric Behavior and Microstructure of Carbon Nanotubes/Carbon Fiber-Cement Based Composite

2011 ◽  
Vol 492 ◽  
pp. 242-245 ◽  
Author(s):  
Jun Qing Zuo ◽  
Wu Yao ◽  
Jun Jie Qin ◽  
Hai Yong Cao
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Fiber ◽  
Thermoelectric Power ◽  
Interfacial Adhesion ◽  
Calcium Silicate Hydrate ◽  
Sem Analysis ◽  
Cement Matrix ◽  
Experimental Setup ◽  
Porous Microstructure ◽  
The Absolute

Thermoelectric behavior and microstructure of carbon nanotubes/carbon fiber(CNTs/CF)- cement based composite have been measured in this study. An self-made experimental setup was applied to test the thermoelectric power (TEP) of the composites. The results show that the higher the CNTs content, the less positive the absolute thermoelectric power is. When CNTs addition incresed to 1.0% by weight of cement, the absolute thermoelectric power changed sign from positive to negative. Scanning electron microscopy (SEM) was used to characterize the morphology of CNTs, CF and the structure of Portland cement-CNTs-CF systems. SEM analysis of the results show that good interfacial adhesion between CNTs and cement matrix is seen with CNTs tightly wrapped by Calcium-Silicate-Hydrate (C-S-H). With the incorporation of CNTs/CF in cement based composite, the cement-CNTs-CF system exhibits a porous microstructure.

Cement as a thermoelectric material

2000 ◽  
Vol 15 (12) ◽  
pp. 2844-2848 ◽  
Author(s):  
Sihai Wen ◽  
D. D. L. Chung
Keyword(s):  
Thermoelectric Power ◽  
Cement Paste ◽  
Carbon Fibers ◽  
Cement Matrix ◽  
Electron Conduction ◽  
Cement Pastes ◽  
Hole Conduction ◽  
Reinforced Cement ◽  
The Absolute ◽  
Short Carbon

Cement pastes containing short steel fibers, which contribute to electron conduction, exhibit positive values (up to 68 μV/°C) of the absolute thermoelectric power. Cement pastes containing short carbon fibers, which contribute to hole conduction while the cement matrix contributes to electron conduction, exhibit negative or slightly positive values of the absolute thermoelectric power. The hole and electron contributions in carbon fiber reinforced cement paste are equal at the percolation threshold. Addition of either steel or carbon fibers to cement paste yields more reversibility and linearity in the variation of the Seebeck voltage with temperature difference (up to 65 °C).

Assessment on the Electrical Conductivity of Additive Fillers into Carbon Fiber-Cement Based Composites

2011 ◽  
Vol 492 ◽  
pp. 185-188 ◽  
Author(s):  
Jun Jie Qin ◽  
Wu Yao ◽  
Jun Qing Zuo ◽  
Hai Yong Cao
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Carbon Fiber ◽  
Percolation Threshold ◽  
Electrical Conduction ◽  
Cement Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

This paper gives an assessment on the electrical conductivity of different additive fillers (graphite, multi-walled carbon nanotubes) into carbon fiber-cement based composites (CFRC). Results show that cement matrix containing 0.4% carbon fiber (CF) and 0.5% multi-walled carbon nanotubes (MWCNTs) exhibits an excellent electrical conductivity of 33.65Ω·cm. When the content of CF is below the percolation threshold (0.4% CF), adding graphite is beneficial to the electrical conduction of CFRC, which has a tremendous drift from 3991.44Ω·cm to 524.33Ω·cm as the content of graphite varies from 0% to 30%. However, when the content of CF is above the percolation threshold, adding graphite makes no advantages in the electrical conductivity of CFRC because of leading to a porosity rising. MWCNTs are useful conductive constituents for CFRC and can increase electrical conductivity by two orders of magnitude. However, excessive adding MWCNTs into CFRC will have a rapid increase of electrical resistivity on the contrary.

Influence of Carbon Nanotubes on Mechanical Properties of High Performance Concrete (HPC)

2016 ◽  
Vol 714 ◽  
pp. 107-110
Author(s):  
Tomáš Vlach ◽  
Lenka Laiblová ◽  
Anuj Kumar ◽  
Alexandru Chira
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
High Performance ◽  
High Performance Concrete ◽  
Experimental Tests ◽  
Negative Influence ◽  
Sem Analysis ◽  
Cement Matrix ◽  
Dispersion Of Nanoparticles ◽  
Scanning Electron

The aim of this work is to study the influence of carbon nanotubes in the cement matrix of high performance concrete (HPC) on flexural and compressive strength. This paper describes the samples preparation for the flexural and compression experimental tests. In order to understand the effect of carbon nanotubes in the cement matrix, a scanning electron microscope (SEM) analysis was carried out. It was reported after experimental tests that an improper dispersion of nanoparticles can have a negative influence on the mechanical properties. The dispersion of carbon nanotubes in the cement matrix is the most important aspect in order to attain the predicated influence on the mechanical properties.

scholarly journals Improving flexural and dielectric properties of carbon fiber epoxy composite laminates reinforced with carbon nanotubes interlayer using electrospray deposition

2020 ◽  
Vol 9 (1) ◽  
pp. 1170-1182
Author(s):  
Muhammad Razlan Zakaria ◽  
Hazizan Md Akil ◽  
Mohd Firdaus Omar ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Aslina Anjang Ab Rahman ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Properties ◽  
Carbon Fiber ◽  
Composite Laminates ◽  
Epoxy Composite ◽  
Flexural Modulus ◽  
X Ray Diffraction ◽  
Electrospray Deposition ◽  
Ft Ir ◽  
Carbon Fiber Epoxy

AbstractThe electrospray deposition method was used to deposit carbon nanotubes (CNT) onto the surfaces of woven carbon fiber (CF) to produce woven hybrid carbon fiber–carbon nanotubes (CF–CNT). Extreme high-resolution field emission scanning electron microscopy (XHR-FESEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the woven hybrid CF–CNT. The results demonstrated that CNT was successfully and homogenously distributed on the woven CF surface. Woven hybrid CF–CNT epoxy composite laminates were then prepared and compared with woven CF epoxy composite laminates in terms of their flexural and dielectric properties. The results indicated that the flexural strength, flexural modulus and dielectric constant of the woven hybrid CF–CNT epoxy composite laminates were improved up to 19, 27 and 25%, respectively, compared with the woven CF epoxy composite laminates.

scholarly journals Macroscopic weavable fibers of carbon nanotubes with giant thermoelectric power factor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Natsumi Komatsu ◽  
Yota Ichinose ◽  
Oliver S. Dewey ◽  
Lauren W. Taylor ◽  
Mitchell A. Trafford ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Fermi Energy ◽  
Performance Enhancement ◽  
Thermoelectric Performance ◽  
Thermoelectric Power Factor ◽  
Large Power ◽  
Energy Tuning

AbstractLow-dimensional materials have recently attracted much interest as thermoelectric materials because of their charge carrier confinement leading to thermoelectric performance enhancement. Carbon nanotubes are promising candidates because of their one-dimensionality in addition to their unique advantages such as flexibility and light weight. However, preserving the large power factor of individual carbon nanotubes in macroscopic assemblies has been challenging, primarily due to poor sample morphology and a lack of proper Fermi energy tuning. Here, we report an ultrahigh value of power factor (14 ± 5 mW m−1 K−2) for macroscopic weavable fibers of aligned carbon nanotubes with ultrahigh electrical and thermal conductivity. The observed giant power factor originates from the ultrahigh electrical conductivity achieved through excellent sample morphology, combined with an enhanced Seebeck coefficient through Fermi energy tuning. We fabricate a textile thermoelectric generator based on these carbon nanotube fibers, which demonstrates high thermoelectric performance, weavability, and scalability. The giant power factor we observe make these fibers strong candidates for the emerging field of thermoelectric active cooling, which requires a large thermoelectric power factor and a large thermal conductivity at the same time.

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