scholarly journals The Effect of Carbon Nanotubes on the Strength of Sand Seeped by Colloidal Silica in Triaxial Testing

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6119
Author(s):  
Weifeng Jin ◽  
Ying Tao ◽  
Xin Wang ◽  
Zheng Gao
Keyword(s):  
Carbon Nanotubes ◽  
Shear Strength ◽  
Carbon Nanotube ◽  
Colloidal Silica ◽  
Ground Improvement ◽  
Silica Gels ◽  
Triaxial Tests ◽  
Sem Images ◽  
Maximum Increase ◽  
Concentration Threshold

Colloidal silica can quickly seep through sand and then form silica gels to cement sand particles. To improve the strength of sand seeped by colloidal silica, carbon nanotubes were dispersed in the colloidal silica to form carbon-nanotube-reinforced sand-gel composites. Then triaxial tests were performed to explore how carbon nanotube content affects shear strength. The test results showed that:(1) with the increase of colloidal silica concentration, the shear strength significantly increased with the same carbon nanotube content (especially the low concentration of 10 wt% colloidal silica, which showed almost no reinforcing effect with carbon nanotubes) while 40 wt% colloidal silica plus 0.01 wt% carbon nanotube caused the maximum increase of shear strength by up to 93.65%; (2) there was a concentration threshold of colloidal silica, above which the shear strength first increased to the peak value and then decreased with increasing carbon nanotube content (and we also established a formula to predict such phenomenon); and (3) SEM images showed that carbon nanotubes were connected as several ropes in the micro-cracks of the silica gel, resulting in greater macroscopic shear strength. Our new method of mixing carbon nanotubes and colloidal silica to seep through sand can contribute to sandy ground improvement.

scholarly journals Advanced Models for Modulus and Strength of Carbon-Nanotube-Filled Polymer Systems Assuming the Networks of Carbon Nanotubes and Interphase Section

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 990
Author(s):  
Yasser Zare ◽  
Kyongyop Rhee
Keyword(s):  
Carbon Nanotubes ◽  
Shear Strength ◽  
Carbon Nanotube ◽  
Interfacial Shear Strength ◽  
Tensile Modulus ◽  
Interfacial Shear ◽  
Filled Polymer ◽  
Polymer Systems

This study focuses on the simultaneous stiffening and percolating characteristics of the interphase section in polymer carbon nanotubes (CNTs) systems (PCNTs) using two advanced models of tensile modulus and strength. The interphase, as a third part around the nanoparticles, influences the mechanical features of such systems. The forecasts agree well with the tentative results, thus validating the advanced models. A CNT radius of >40 nm and CNT length of <5 μm marginally improve the modulus by 70%, while the highest modulus development of 350% is achieved with the thinnest nanoparticles. Furthermore, the highest improvement in nanocomposite’s strength (350%) is achieved with the CNT length of 12 μm and interfacial shear strength of 8 MPa. Generally, the highest ranges of the CNT length, interphase thickness, interphase modulus and interfacial shear strength lead to the most desirable mechanical features.

Carbon Nanotube Reinforced Fused Deposition Modeling Using Microwave Irradiation

2016 ◽  
Author(s):  
Meng Zhang ◽  
Xiaoxu Song ◽  
Weston Grove ◽  
Emmett Hull ◽  
Z. J. Pei ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Additive Manufacturing ◽  
Microwave Irradiation ◽  
Computer Aided Design ◽  
Fused Deposition Modeling ◽  
Layer By Layer ◽  
Sem Images ◽  
Fused Deposition ◽  
Deposition Modeling

Additive manufacturing (AM) is a class of manufacturing processes where material is deposited in a layer-by-layer fashion to fabricate a three-dimensional part directly from a computer-aided design model. With a current market share of 44%, thermoplastic-based additive manufacturing such as fused deposition modeling (FDM) is a prevailing technology. A key challenge for AM parts (especially for parts made by FDM) in engineering applications is the weak inter-layer adhesion. The lack of bonding between filaments usually results in delamination and mechanical failure. To address this challenge, this study embedded carbon nanotubes into acrylonitrile butadiene styrene (ABS) thermoplastics via a filament extrusion process. The vigorous response of carbon nanotubes to microwave irradiation, leading to the release of a large amount of heat, is used to melt the ABS thermoplastic matrix adjacent to carbon nanotubes within a very short time period. This treatment is found to enhance the inter-layer adhesion without bulk heating to deform the 3D printed parts. Tensile and flexural tests were performed to evaluation the effects of microwave irradiation on mechanical properties of the specimens made by FDM. Scanning electron microscopic (SEM) images were taken to characterize the fracture surfaces of tensile test specimens. The actual carbon nanotube contents in the filaments were measured by conducting thermogravimetric analysis (TGA). The effects of microwave irradiation on the electrical resistivity of the filament were also reported.

Exploring the mechanical response of low-carbon soil improvement mixtures

2021 ◽  
Author(s):  
Alessandro Fraccica ◽  
Giovanni Spagnoli ◽  
Enrique E. Romero Morales ◽  
Marcos Arroyo ◽  
Rodrigo Gómez
Keyword(s):  
Colloidal Silica ◽  
Mechanical Response ◽  
Ground Improvement ◽  
Soil Improvement ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Granular Soils ◽  
Low Carbon ◽  
Cyclic Triaxial Tests ◽  
Curing Conditions

As society moves towards decarbonisation it is important to assess the hydro-mechanical behaviour of binders that could offer a low-carbon alternative to Portland cement in ground improvement technologies. This work considers two such alterna-tives: one still largely unexplored (metakaolin-based geopolymers) and a better known one (colloidal silica). Results from unconfined compressive strength, permeability tests, undrained monotonic and cyclic triaxial tests on granular soils (sand and silty sand) treated with those two binders are presented and discussed, emphasizing simili-tudes and differences with the response of similar soils treated with other conventional and unconventional binders. Effects of silt content, curing conditions and soil/binder ratios are examined. Both colloidal silica and metakaolin-based geopolymer signifi-cantly improve the mechanical properties of the treated soils, although the geopolymer results in a stronger and stiffer material. Both treatments reduce much the permeabil-ity of the treated soil, but the reduction achieved with CS is larger.

Molecular Dynamics Study of Carbon Nanotubes in Bundles

2006 ◽  
Author(s):  
Lars R. Jensen ◽  
Ryszard Pyrz
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Shear Strength ◽  
Carbon Nanotube ◽  
Cross Section ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Tube Diameter ◽  
Nanotube Bundles ◽  
Geometrical Transformation

Molecular mechanics and dynamics have applied to study the behavior of single wall carbon nanotube bundles. A geometrical transformation of the nanotube cross section was observed when the tube diameter exceeded 1,4 nm where the cross section changed from circular to hexagonal. The elastic properties of the bundles were examined and shown to depend on the tube diameter but not on the geometrical transition. The interfacial shear strength between the adjacent tubes was estimated and shown to depend both on the diameter and on the geometrical transition.

scholarly journals Effects of critical interfacial shear strength between a polymer matrix and carbon nanotubes on the interphase strength and Pukanszky's “B” interphase parameter

RSC Advances ◽  
2020 ◽  
Vol 10 (23) ◽  
pp. 13573-13582
Author(s):  
Yasser Zare ◽  
Kyong Yop Rhee
Keyword(s):  
Carbon Nanotubes ◽  
Shear Strength ◽  
Carbon Nanotube ◽  
Polymer Matrix ◽  
Interfacial Shear Strength ◽  
Interfacial Shear

In this paper, the “B” interphase parameter in the Pukanszky model and interphase strength for polymer carbon nanotube (CNT) nanocomposites are expressed by the critical interfacial shear strength (τc) and interfacial shear strength (τ) between a polymer matrix and CNTs.

scholarly journals The Mechanical Response of a Silty Sand Stabilized with Colloidal Silica

Geotechnics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 243-259
Author(s):  
Antigoni Vranna ◽  
Theodora Tika
Keyword(s):  
Shear Strength ◽  
Colloidal Silica ◽  
Mechanical Response ◽  
Axial Strain ◽  
Undrained Shear Strength ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Cyclic Straining ◽  
Sand Stabilized ◽  
Undrained Shear

This paper presents a laboratory investigation into the mechanical response of a silty sand, with a fines content of 10%, stabilized with colloidal silica (CS). To this end, a series of unconfined compression tests as well as monotonic and cyclic triaxial tests was performed on a silty sand, comprising a mixture of a clean sand and a silty sand, stabilized with two concentrations of CS. The effect of various parameters on the behaviour of the stabilized silty sand was studied, such as CS concentration, soil density, and the presence of fines. The test results were compared with the corresponding of the untreated silty sand as well as the parent clean sand. It is shown that stabilization, even at the lowest CS = 6% concentration studied, significantly improves the undrained shear strength as well as the liquefaction resistance of the stabilized silty sand. Both the monotonic and cyclic response of the stabilized soil are only slightly affected by density. Furthermore, cyclic straining up to at least 5% of double-amplitude axial strain does not influence the undrained shear strength of the stabilized silty sand.

Influence of Multiwall Carbon Nanotube on mechanical and wear properties of Copper – Iron composite

2020 ◽  
Vol 17 (1) ◽  
pp. 7570-7576 ◽  
Author(s):  
H. Sh. Hammood ◽  
S. S. Irhayyim ◽  
A. Y. Awad ◽  
H. A. Abdulhadi
Keyword(s):  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Hydraulic Press ◽  
Dry Sliding Wear ◽  
Multiwall Carbon Nanotube ◽  
Wear Properties ◽  
Sem Images ◽  
Wear Rates ◽  
Multiwall Carbon

Multiwall Carbon nanotubes (MWCNTs) are frequently attractive due to their novel physical and chemical characteristics, as well as their larger aspect ratio and higher conductivity. Therefore, MWCNTs can allow tremendous possibilities for the improvement of the necessarily unique composite materials system. The present work deals with the fabrication of Cu-Fe/CNTs hybrid composites manufactured by powder metallurgy techniques. Copper powder with 10 vol. % of iron powder and different volume fractions of Multi-Wall Carbon Nanotubes (MWCNTs) were mixed to get hybrid composites. The hybrid composites were fabricated by adding 0.3, 0.6, 0.9, and 1.2 vol.% of MWCNTs to Cu- 10% Fe mixture using a mechanical mixer. The samples were compressed under a load of 700 MPa using a hydraulic press to compact the samples. Sintering was done at 900°C for 2 h at 5ºC/min heating rate. The microscopic structure was studied using a Scanning Electron Microscope (SEM). The effect of CNTs on the mechanical and wear properties, such as micro-hardness, dry sliding wear, density, and porosity were studied in detail. The wear tests were carried out at a fixed time of 20 minutes while the applied loads were varied (5, 10, 15, and 20 N). SEM images revealed that CNTs were uniformly distributed with relative agglomeration within the Cu/Fe matrix. The results showed that the hardness, density, and wear rates decreased while the percentage of porosity increased with increasing the CNT volume fraction. Furthermore, the wear rate for all the CNTs contents increased with the applied load.

Fabrication of Carbon Nanotube Triode Using Helicon Plasma Cvd with Electroplated Nico Catalyst

2003 ◽  
Vol 772 ◽  
Author(s):  
Masakazu Muroyama ◽  
Kazuto Kimura ◽  
Takao Yagi ◽  
Ichiro Saito
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Metal Catalyst ◽  
Ni Catalyst ◽  
Plasma Cvd ◽  
Helicon Plasma ◽  
Plasma Enhanced Cvd ◽  
Turn On ◽  
Aligned Carbon Nanotubes ◽  
Vertically Aligned

AbstractA carbon nanotube triode using Helicon Plasma-enhanced CVD with electroplated NiCo catalyst has been successfully fabricated. Isolated NiCo based metal catalyst was deposited at the bottom of the cathode wells by electroplating methods to control the density of carbon nanotubes and also reduce the activation energy of its growth. Helicon Plasma-enhanced CVD (HPECVD) has been used to deposit nanotubes at 400°C. Vertically aligned carbon nanotubes were then grown selectively on the electroplated Ni catalyst. Field emission measurements were performed with a triode structure. At a cathode to anode gap of 1.1mm, the turn on voltage for the gate was 170V.

scholarly journals Explosive Molecule Sensing at Lattice Defect Sites in Metallic Carbon Nanotubes

2021 ◽  
Author(s):  
Manasi Doshi ◽  
Eric Paul Fahrenthold
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Experimental Research ◽  
Gas Sensing ◽  
Lattice Defect ◽  
Sensing Mechanism ◽  
Defect Sites ◽  
Chemiresistive Sensing ◽  
Hazardous Gas

Explosives and hazardous gas sensing using carbon nanotube (CNT) based sensors has been a focus of considerable experimental research. The simplest sensors have employed a chemiresistive sensing mechanism, and rely...

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