scholarly journals High-temperature ferromagnetism of helical carbon nanotubes

AIP Advances ◽  
2013 ◽  
Vol 3 (5) ◽  
pp. 052112 ◽  
Author(s):  
Ye Zhuang ◽  
Jianfeng Wen ◽  
Nujiang Tang ◽  
Ming Li ◽  
Liya Lv ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Temperature ◽  
Helical Carbon Nanotubes

Structural and surface modifications of carbon nanotubes when submitted to high temperature annealing treatments

2012 ◽  
Vol 536 ◽  
pp. S460-S463 ◽  
Author(s):  
E. Castillejos ◽  
B. Bachiller-Baeza ◽  
M. Pérez-Cadenas ◽  
E. Gallegos-Suarez ◽  
I. Rodríguez-Ramos ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Temperature ◽  
Surface Modifications ◽  
High Temperature Annealing

New Generation of SiC Based Biodevices Implemented on 4” Wafers

2010 ◽  
Vol 645-648 ◽  
pp. 1097-1100 ◽  
Author(s):  
Phillippe Godignon ◽  
Iñigo Martin ◽  
Gemma Gabriel ◽  
Rodrigo Gomez ◽  
Marcel Placidi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Silicon Carbide ◽  
High Temperature ◽  
Temperature Sensors ◽  
Biomedical Devices ◽  
Power Semiconductor ◽  
Power Semiconductor Devices ◽  
New Generation ◽  
Growth Technology ◽  
Biosensor Applications

Silicon Carbide is mainly used for power semiconductor devices fabrication. However, SiC material also offers attractive properties for other types of applications, such as high temperature sensors and biomedical devices. Micro-electrodes arrays are one of the leading biosensor applications. Semi-insulating SiC can be used to implement these devices, offering higher performances than Silicon. In addition, it can be combined with Carbon Nanotubes growth technology to improve the devices sensing performances. Other biosensors were SiC could be used are microfluidic based devices. However, improvement of SiCOI starting material is necessary to fulfill the typical requirements of such applications.

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.

Zaczyny cementowe z dodatkiem nanorurek węglowych do uszczelniania otworów wiertniczych o wysokiej temperaturze i ciśnieniu złożowym (150°C, 90 MPa)

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (5) ◽  
pp. 323-331
Author(s):  
Miłosz Kędzierski ◽  
◽  
Marcin Rzepka ◽  
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
High Temperature ◽  
Rheological Parameters ◽  
External Diameter ◽  
Mechanical Parameters ◽  
Cement Slurry ◽  
Significant Information ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

The article presents the results of the influence of carbon nanotubes on the mechanical parameters of cement stones under high temperature and pressure conditions (150°C, 90 MPa). The tests used multi-walled carbon nanotubes (MWCNTs) with an external diameter of 10–20 nm and a length of 10–30 μm. Cement slurries contained 0.1% of CNTs bwoc (by the weight of cement). Laboratory tests of cement slurries were carried out at the Oil and Gas Institute – National Research Institute. The tests were carried out under conditions of increased pressure and temperature at 150°C, 90 MPa. Cement slurries were prepared on the basis of class G drilling cement. Developing recipes were guided by the requirements to be met by cement slurry for the cementing of casing in the conditions of high temperature and reservoir pressures. The densities of tested slurries ranged from 1900 kg/m3 to 2250 kg/m3 (slurries with the addition of hematite). The cement slurries were tested for density, fluidity, rheological parameters, filtration and thickening time. Compressive strength tests and measuring adhesion were carried out after 2, 7, 14 and 28 days. Cement slurry recipes with very good technological parameters were developed and after curing (after 28 days of hydration) had very high values of compressive strength, reaching up to 45 MPa. Cements were characterized by high values of adhesion to pipes reaching up 7 MPa after 28 days. The research showed significant information about possible applications of carbon nanotubes to modify the cement slurry under conditions of high temperature and pressure. The conducted tests confirmed that the addition of even small amounts of CNTs improves the mechanical parameters of the cement stone compared to the base sample without such addition, and also reduces the thickening time of cement slurries and reduces filtration. It is investigated that CNTs addition increases the viscosity and yield point of cement slurry. As a result, slurries with the addition of MWCNTs will more effectively displace the mud from the borehole and significantly affect the quality of cementation.

scholarly journals Fracture toughness of one- and two-dimensional nanoreinforced cement via scratch testing

2021 ◽  
Vol 379 (2203) ◽  
pp. 20200288 ◽  
Author(s):  
Ange-Therese Akono
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Cement Industry ◽  
Vertical Force ◽  
Two Dimensional ◽  
Scratch Testing ◽  
Helical Carbon Nanotubes ◽  
Reinforced Cement ◽  
Carbon Based Nanomaterials ◽  
Carbon Based

Cement is the most widely consumed material globally, with the cement industry accounting for 8% of human-caused greenhouse gas emissions. Aiming for cement composites with a reduced carbon footprint, this study investigates the potential of nanomaterials to improve mechanical characteristics. An important question is to increase the fraction of carbon-based nanomaterials within cement matrices while controlling the microstructure and enhancing the mechanical performance. Specifically, this study investigates the fracture response of Portland cement reinforced with one- and two-dimensional carbon-based nanomaterials, such as carbon nanofibres, multiwalled carbon nanotubes, helical carbon nanotubes and graphene oxide nanoplatelets. Novel processing routes are shown to incorporate 0.1–0.5 wt% of nanomaterials into cement using a quadratic distribution of ultrasonic energy. Scratch testing is used to probe the fracture response by pushing a sphero-conical probe against the surface of the material under a linearly increasing vertical force. Fracture toughness is then computed using a nonlinear fracture mechanics model. Nanomaterials are shown to bridge nanoscale air voids, leading to pore refinement, and a decrease in the porosity and the water absorption. An improvement in fracture toughness is observed in cement nanocomposites, with a positive correlation between the fracture toughness and the mass fraction of nanofiller for graphene-reinforced cement. Moreover, for graphene-reinforced cement, the fracture toughness values are in the range of 0.701 to 0.717 MPa m . Thus, this study illustrates the potential of nanomaterials to toughen cement while improving the microstructure and water resistance properties. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

scholarly journals Molecular dynamics simulation of the evaporation of the surface wall of multi-wall carbon nanotubes at high temperature

2010 ◽  
Vol 59 (4) ◽  
pp. 2672
Author(s):  
Wang Wei ◽  
Zhang Kai-Wang ◽  
Meng Li-Jun ◽  
Li Zhong-Qiu ◽  
Zuo Xue-Yun ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
High Temperature ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Multi Wall Carbon Nanotubes
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