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.

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.

Fabrication of Al5083 surface hybrid nanocomposite reinforced by CNTs and Al2O3 nanoparticles using friction stir processing

2019 ◽  
Vol 54 (8) ◽  
pp. 1107-1117 ◽  
Author(s):  
Farhad Ostovan ◽  
Sattar Amanollah ◽  
Meysam Toozandehjani ◽  
Ehsan Shafiei
Keyword(s):  
Wear Resistance ◽  
Grain Boundary ◽  
Friction Stir Processing ◽  
Weight Fraction ◽  
Point Of View ◽  
Al2o3 Nanoparticles ◽  
Hybrid Nanocomposite ◽  
Friction Stir ◽  
Mechanical And Tribological Properties ◽  
Uniform Dispersion

In the present study, friction stir processing was adopted for surface treatment of Al5083 by incorporation of CNT and Al2O3 nanoparticles. Microstructural, mechanical and tribological properties of the surface of Al5083/CNT, Al5083/Al2O3 and hybrid Al5083/CNT/Al2O3 nanocomposite were investigated and compared. The friction stir processing yielded a nearly uniform dispersion of CNTs and Al2O3 nanoparticles, irrespective of nanoparticle reinforcements and their weight fraction. Microstructural observations revealed that Al2O3 nanoparticles have dispersed in different zones including intra-grain and grain boundary zones while, CNTs are pinned into grain boundaries during friction stir processing. From mechanical point of view, hybridization of CNT/Al2O3 enhances the hardness (126 HV at stirred zone), strength (UTS of ∼487 MPa) and also wear resistance of Al5083/CNT/Al2O3 nanocomposites. The enhancement is attributed to the presence and combination of features of both CNT and Al2O3 nanoparticles which are different in nature; one spherical oxide and one nanotube.

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 Influence of tool pin and shoulder geometries on microstructure of friction stir processed AA6063/SiC composites

2018 ◽  
Vol 19 (2) ◽  
pp. 211 ◽  
Author(s):  
Namrata Gangil ◽  
Sachin Maheshwari ◽  
Arshad Noor Siddiquee
Keyword(s):  
Friction Stir Processing ◽  
Particle Distribution ◽  
Combined Effect ◽  
Stir Zone ◽  
Friction Stir ◽  
Single Pass ◽  
Microstructure Examination ◽  
Sic Composites ◽  
Tool Pin

The present study investigated the combined effect of friction stir processing (FSP) tool pin and shoulder profiles on particle distribution and microstructure of AA6063/SiC composites. Two strategies were used, in first strategy, plain cylindrical, tapered cylindrical, square and triangular tool pin profiles were used with flat shoulder design. In second strategy square and cylindrical pin profiles were used along with clock-wise (CW) and anti clock-wise (ACW) scrolled shoulder design. Single pass processing was performed to fabricate the composites. Microstructure examination of sample processed with various pin profiles and flat shoulder design reveals that tool with square pin profile was most effective. Among other shoulder profiles, ACW scrolled shoulder resulted in pancake shaped stir zone (SZ) and exhibited significant improvement in SZ size, out of which ACW scrolled shoulder with cylindrical pin profile produced uniform particle distribution without any defects.

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.

Effect of microstructure and precipitate formation on mechanical and corrosion behavior of friction stir processed AA6061 alloy using different cooling media

2021 ◽  
pp. 146442072110057
Author(s):  
Marukurti VNV Satyanarayana ◽  
Adepu Kumar ◽  
Shivraman Thapliyal
Keyword(s):  
Corrosion Resistance ◽  
Friction Stir Processing ◽  
Base Alloy ◽  
Base Material ◽  
Stir Zone ◽  
Grain Structure ◽  
Precipitate Formation ◽  
Friction Stir ◽  
Aa6061 Alloy ◽  
Effect Of Microstructure

The present work studies the effect of microstructure and precipitate formation on mechanical and corrosion characteristics of friction stir processed AA6061 alloy using different cooling technologies (cryogenic and water cooling). The results revealed that recrystallized fine grains formed in all friction stir processing samples (grain size within a range of 2–6 µm) as a result of dynamic recovery and recrystallization, while samples processed in cooling-assisted friction stir processing resulted in better grain refinement in the stir zone than in air-cooled friction stir processing. Three kinds of precipitates (Fe-based needle-shaped precipitates, Si-based round-shaped precipitates, and chain of small round-shaped Si-based precipitates) were identified in base material and friction stir processing samples. Compared to air-cooled friction stir processing, in cooling-assisted friction stir processing, the hardness and tensile strength increased but remained lower than for the base alloy due to the presence of high density Fe-based needle-shaped precipitates. The ductility after friction stir processing greatly improved due to thermal softening and dissolution of precipitates. The corrosion results demonstrated that the corrosion resistance greatly enhanced after friction stir processing due to uniform distribution of grain structure and discontinuous chain of small round-shaped Si-based precipitates in stir zone. Moreover, cooling-assisted friction stir processing resulted in improved corrosion resistance compared to air-cooled friction stir processing due to the formation of fine precipitates.

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