scholarly journals Mirostructure and microhardness of aluminum-copper composite reinforced with multi-walled carbon nanotubes prepared by vacuum sintering and hot isostatic pressing techniques

2018 ◽  
Vol 50 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Van Trinh ◽  
Van Luan ◽  
Doan Phuong ◽  
Phan Minh
Keyword(s):  
Carbon Nanotubes ◽  
Hot Isostatic Pressing ◽  
High Energy ◽  
Strengthening Effect ◽  
Vacuum Sintering ◽  
Composite Powders ◽  
Isostatic Pressing ◽  
Uniform Dispersion ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this study, we report the processing, microstructure, and microhardness of aluminum-copper composites reinforced with multi-walled carbon nanotubes (CNTs). Composite powders were prepared by a high energy ball (HEB) milling process then consolidated by vacuum sintering and hot isostatic pressing (HIP) techniques. The specimens show a uniform dispersion of CNTs in the Al-Cu matrix with CNT content up to 1 wt.% and a cluster formation observed with higher CNT content of 1.5 wt.%. The specimens have a relative density of 92 % to 95 % for composites sintered by vacuum sintering and 93 % to 96 % for composites sintered by HIP. Microhardness of specimens increases with increasing CNT content up to 1_wt% and then decreases due to the formation of CNT clusters. Microhardness is enhanced both by the dispersion strengthening effect of CNTs and by precipitation hardening of Al-Cu matrix.

Multi-Walled Carbon Nanotubes Reinforced Titanium Composites via Powder Metallurgy Process

2012 ◽  
Vol 520 ◽  
pp. 261-268 ◽  
Author(s):  
Katsuyoshi Kondoh ◽  
Thotsaphon Threrujirapapong ◽  
Sun Bin ◽  
Hisashi Imai ◽  
Shu Feng Li ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Tensile Strength ◽  
Powder Metallurgy ◽  
Titanium Powder ◽  
Fine Particles ◽  
Pure Titanium ◽  
Strengthening Effect ◽  
Composite Powders ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Un-bundled multi-walled carbon nanotubes (MWCNTs) were coated on titanium powder surface by using zwitterionic surfactant solution and mixing process, and their CNT/Ti composite powders were consolidated into full-dense materials by spark plasma sintering and the following hot extrusion process in solid-state. Wrought titanium powder metallurgy (PM) composites containing CNTs revealed extreme increment of yield stress and tensile strength of 85% and 50%, respectively, compared to conventional PM titanium with no reinforcement, while they had enough high ductility. The mechanical improvement was mainly due to dispersion strengthening effect of CNTs and in-situ formed TiC fine particles and a small mount of carbon solid solution into Ti matrix. In addition, the control of grain growth was promoted by TiC dispersoids during SPS, and contributed to their strengthening behavior. Furthermore, high-temperature tensile strength less than 673K of PM pure titanium materials was also obviously improved by the pinning effect of TiC particles dispersed at grain boundaries. In this paper, microstructural and mechanical properties of powder metallurgy titanium composites would be introduced in detail.

Two-step synthesis of polyurethane/multi-walled carbon nanotubes polymer composite to achieve high percentage particle reinforcement for mechanical applications

2021 ◽  
pp. 002199832199945
Author(s):  
Dinesh Kumar ◽  
Suneev Anil Bansal ◽  
Navin Kumar ◽  
Prashant Jindal
Keyword(s):  
Carbon Nanotubes ◽  
Synthesis Method ◽  
Step Method ◽  
Molding Method ◽  
Uniform Dispersion ◽  
Noticeable Improvement ◽  
Multi Walled Carbon Nanotubes ◽  
Mixing Method ◽  
Compressive Testing ◽  
Walled Carbon Nanotubes

The present work has been aimed to synthesize Polyurethane (PU)/Multi-Walled Carbon Nanotubes (MWCNTs) composite using a two-step method to enhance mechanical properties. In the first step, films (0.2 mm thickness) have been synthesized using a solution mixing method to disperse MWCNTs in the PU matrix. In the second step, thin films of uniformly dispersed MWCNTs in the PU matrix have been compression molded to synthesize PU/MWCNTs composite required for real mechanical applications. The two-step method has the advantages of solution mixing as well as compression molding method. The results of quasi-static nanoindentation tests indicated that in comparison to pure PU, elastic modulus and hardness have been enhanced by 124% and 53% respectively for 10 wt% PU/MWCNTs composite. Fracture resistance of PU/MWCNTs composites, with 7 wt% of MWCNTs, has been enhanced by 52% as compared to pure PU. To understand bulk behavior, nanoindentation results have been cross-verified with compression testing. Results of compressive testing shown that the modulus of composite material has been significantly improved under the influence of the increasing composition of MWCNTs. A noticeable improvement of 52% has been observed in compressive modulus of 10 wt% composite in equivalence to pure PU. The overall improvement in mechanical behavior has been attributed to the uniform dispersion of MWCNTs in the PU matrix by the two-step synthesis method.

Dispersion of Multi-Walled Carbon Nanotubes in Portland Cement Concrete Using Ultra-Sonication and Polycarboxylic Based Superplasticizer

2015 ◽  
Vol 802 ◽  
pp. 112-117 ◽  
Author(s):  
Ali Yousefi ◽  
Norazura Muhamad Bunnori ◽  
Mehrnoush Khavarian ◽  
Taksiah A. Majid
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Portland Cement ◽  
Cement Matrix ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Uniform Dispersion ◽  
Multi Walled Carbon Nanotubes ◽  
Sonication Technique ◽  
Walled Carbon Nanotubes

The potential properties of carbon nanotube-cement based materials strongly depend on the dispersion of carbon nanotubes (CNTs) within the cement matrix and the bonding between CNTs and the hydrated cement. The homogeneous dispersion of CNTs in the cement matrix yet is one of the main challenges due to strong van der Waals forces between nanotubes. In this study, a polycarboxylic ether based superplasticizer and ultra-sonication technique was used for dispersion of multi-walled carbon nanotubes (MWCNTs). Portland cement concrete specimens with different concentrations of MWCNTs (0.04 and 0.1 % by the weight of cement), with and without the presence of superplasticizer were investigated. Compressive strength test results revealed a significant improvement in mechanical properties of sample containing 0.1 % MWCNTs and 0.2 % superplasticizer. Moreover, field emission scanning electron microscopy (FESEM) images of fractured surfaces of hardened specimens showed a good dispersion of MWCNTs within the cement matrix. This method was developed to facilitate the uniform dispersion of MWCNTs in the cementitious concrete for better reinforcement in nanoscale and mechanical properties enhancement by transfer of load between the nanotubes and matrix.

scholarly journals Uniform Dispersion and Exfoliation of Multi-Walled Carbon Nanotubes in CNT-MgB2 Superconductor Composites Using Surfactants

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3044
Author(s):  
Mohammed Shahabuddin ◽  
Niyaz Ahamad Madhar ◽  
Nasser S. Alzayed ◽  
Mohammad Asif
Keyword(s):  
Carbon Nanotubes ◽  
Colloidal Suspension ◽  
Direct Synthesis ◽  
Cost Effective ◽  
Heat Processing ◽  
Synthesis Route ◽  
Uniform Dispersion ◽  
Multi Walled Carbon Nanotubes ◽  
Magnetic Resonance Imaging Mri ◽  
Walled Carbon Nanotubes

We developed a novel yet commercially viable strategy of synthesizing superior high-TC superconducting composites by dispersing fully exfoliated carbon nanotubes (CNTs) uniformly throughout the grain of CNT-MgB2 composites. First, we optimized the amount of the surfactant required to produce a highly stable and homogeneous colloidal suspension of CNTs. This amount was found to be 1/8th of the amount of CNTs. Second, we prepared a homogeneous CNT-B mixture by adding amorphous nano-boron (B) to the colloidal CNT suspension. Next, two different MgB2 synthesis routes were explored. In one case, we mixed an appropriate amount of Mg in the CNT-B mixture and carried out sintering. In the second case, the CNT-B mixture was heat treated at 500 °C, prior to mixing with Mg and sintering to form CNT-MgB2. Both kinds of samples were rigorously characterized to obtain an insight into their properties. The direct synthesis route shows a clear exfoliation and uniform dispersion of CNTs with a critical current density (JC) of 104 A/cm2 at 3.5 T and 20 K, which is useful for the application in magnetic resonance imaging MRI magnet operating with a cryogen free cooler. Our JC(H) result is 10 times higher than that of the pure sample. By contrast, the performance of the sample subjected to heat processing before sintering was severely compromised given the formation of MgO. Despite its simplicity, the direct synthesis route can be used for the cost-effective fabrication of CNT–MgB2 superconducting composites.

scholarly journals Load Sensing Capability of Cementitious Matrixes—Nanomodified Cement Versus Carbon Nanotube Dispersion

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 19
Author(s):  
Buasiri ◽  
Habermehl-Cwirzen ◽  
Krzeminski ◽  
Cwirzen
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Properties ◽  
Carbon Nanomaterials ◽  
Compressive Load ◽  
Weight Changes ◽  
Load Sensing ◽  
Carbon Nanotube Dispersion ◽  
Uniform Dispersion ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

A cement-based matrix incorporating conductive materials such as carbon nanotubes and carbon nanofibers can have self-sensing capability. Both nanomaterials are characterized by excellent physical, mechanical and electrical properties. A disadvantage is that due to their hydrophobic nature it is very difficult to ensure uniform dispersion throughout the cementitious matrix. To overcome this problem a new nanomodified cement containing in-situ attached CNFs was developed leading to a very homogenous and conductive binder matrix. This study aimed to compare the piezoresistive responses of two types of matrixes, one based on the nanomodified cement and the second containing multi-walled carbon nanotubes. Several mortars were prepared containing either MWCNTs or the nanomodified cement, which partially replaced the untreated cement. The effective amount of the carbon nanomaterials was the same for both types of mixes and ranged from 0 wt.% to 0.271 wt.%, calculated by the all binder weight. Changes in the electrical properties were determined while applying compressive load. The results showed that the binders based on the nanomodified cement have significantly better load sensing capabilities and are suitable for applications in monitoring systems.

Simulation and experimental investigation of multi-walled carbon nanotubes/aluminum composite fabrication using friction stir processing

2021 ◽  
pp. 095440892110340
Author(s):  
Mostafa Akbari ◽  
Parviz Asadi
Keyword(s):  
Carbon Nanotubes ◽  
Wear Resistance ◽  
Friction Stir Processing ◽  
Particle Distribution ◽  
Base Alloy ◽  
Stir Zone ◽  
Friction Stir ◽  
Uniform Dispersion ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotube/aluminum composites are fabricated on Al–Si cast alloy employing friction stir processing. First, the microstructure of the stir zone, as well as the effect of process parameters on the size of silicon particles, is investigated. Then, the process is numerically simulated using a thermo-mechanically coupled three-dimensional finite element method model. Material flow, as the primary reason for the dispersion of reinforcing particles, is considered in the numerical model, and proper conditions to obtain a uniform dispersion of multi-walled carbon nanotubes are determined. Scanning electron microscope analysis is carried out to consider the particle distribution in the texture of the stir zone. The results show that the particle distribution improves significantly by changing the tool rotation direction between the friction stir processing passes. The hardness test is accomplished on the cross-section of the friction stir processed specimens, and finally, the wear test is performed to compare the wear resistance of the composites with the base alloy. The results show that the wear resistance and hardness of the produced composites are considerably enhanced compared to the base alloy.

The Microstructure, Mechanical and Dielectric Properties of CNTs/Mullite Ceramics Composites

2006 ◽  
Vol 313 ◽  
pp. 145-150 ◽  
Author(s):  
Jing Wang ◽  
Hua Min Kou ◽  
Yu Bai Pan ◽  
Jing Kun Guo
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Bending Strength ◽  
Composite Powders ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Mullite Ceramics ◽  
Dissipative Factor

Carbon nanotube-mullite (Al2O3/SiO2=3/2) composites have been prepared by hot-pressing the corresponding composite powders, in which the multi-walled carbon nanotubes(1~10 vol%) are homogeneously dispersed between the mullite grains. The microstructure of the specimens has been studied and discussed in relation to the properties of the matrix, the bending strength and the fracture toughness, the dielectric constant and the dissipative factor. Carbon nanotube-mullite composites are potential electromagnetic wave absorbers owing to the percolation of the carbon nanotubes.

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