Effect Of Carbon Nanotubes Content Research Articles

Effect of carbon nanotubes on mechanical properties of aluminum matrix composites: A review

Abstract Carbon nanotubes (CNTs) are renowned for their low density, high elastic modulus, and exceptional electrical and thermal properties. The continuously developing applications of CNTs provide higher specific stiffness and strength for composite materials. The unique characteristics of CNTs make them ideal reinforcing particles in aluminum matrix composites (AMMCs), which generally exhibit excellent mechanical properties. CNTs/AMMCs are usually prepared using methods such as powder metallurgy, casting, spray deposition, and reactive melting. The uniform diffusion of CNTs in composites is crucial for enhancing the properties of CNTs/AMMCs. The properties of CNTs/AMMCs largely depend on the content, morphology, and distribution of reinforcements in the matrix and the interaction between reinforcements and the matrix. By adding an appropriate volume fraction of CNTs, the hardness, tensile strength, compressive strength, and electrical properties of CNTs/AMMCs were significantly improved. The effects of CNT content on the mechanical properties of CNTs/AMMCs, including the tensile strength, yield strength, compressive strength, stress–strain curve behavior, elastic modulus, hardness, creep, and fatigue behavior, were revealed. The design of microstructure, optimization of the preparation process, and optimization of composition can further improve the mechanical properties of CNTs/AMMCs and expand their application in engineering. The design concept of integrating material homogenization and functional unit structure through biomimetic design of novel gradient structures, layered structures, and multi-level twin structures further optimizes the composition and microstructure of CNTs/AMMCs, which is the key to further obtaining high-performance CNTs/AMMCs. As a multifunctional composite material, CNTs/AMMCs have broad application prospects in fields such as air force, military, aerospace, automation, and electronics. Moreover, CNTs/AMMCs have potential applications in cell therapy, tissue engineering, and other areas.

Electrospun thermoplastic polyurethane membrane decorated with carbon nanotubes: A platform of flexible strain sensors for human motion monitoring

A piezoresistive flexible strain sensor was developed using thermoplastic polyurethane elastomers (TPU) as the matrix and carbon nanotubes (CNTs) as conductive fillers. Sensitivity, strain range, and tensile cycling stability were concurrently considered during its design. Electrospun TPU fiber membranes were prepared via electrospinning in this experiment, with controllable fiber diameter achieved by adjusting the rotational speed of the electrospinning receiving drum. CNTs were incorporated into a flexible polymer substrate through suction filtration to create the strain sensor. The support structure of the electrospun film served as a carrier for uniformly adhering conductive particles. Well-dispersed conductive CNTs could more easily achieve uniform loading through the pore size of the electrospun fiber film, thereby forming a conductive layer. This study initially determined the influence of TPU content in the spinning solution on the morphology of the electrospun membrane. Subsequently, the effects of CNT content and electrospinning receiving drum rotational speed on the microstructure of TPU electrospun membranes were investigated, along with their impact on the microstructure, mechanical properties, and sensing performance of CNTs/TPU (CT) flexible strain sensors. The results indicate that the electrospun fiber membrane prepared under the conditions of TPU mass fraction of 20 wt% and rotational speed of 100 r/min has a larger average fiber diameter and a more stable scaffold structure. The CNTs/TPU (CT) sensor, prepared by filtering 10 mL of CNTs with a concentration of 2 mg/mL, exhibited the best mechanical properties, with a tensile strength and elongation at break of 6.22 MPa and 575 %, respectively. Additionally, it demonstrated high sensitivity (GF = 420.17 at 200 % strain) and excellent durability stability (300 cycle tests), enabling quick and accurate responses to movements of various parts of the human body, thereby meeting the basic usage requirements of flexible strain sensors.

Influence of PLA/HDPE Ratio and CNT content on the morphology, electrical, and EMI shielding of CNT-filled PLA/HDPE blends

The influence of polylactic acid/high-density polyethylene (PLA/HDPE) volume ratio on the microstructure, electrical resistivity, and electromagnetic interference (EMI) shielding effectiveness (SE) of 1.0 vol% carbon nanotube (CNT) filled PLA/HDPE composites were investigated. Also, the effect of CNT content on the electrical resistivity and EMI SE of 90/10, 50/50, and 10/90 PLA/HDPE blends were studied. The CNT/PLA composite showed superior electrical and EMI SE performance compared with the CNT/HDPE composite. In the PLA/HDPE blends, the nanotubes were selectively localized in the HDPE domain. The EMI SE and electrical conductivity increased with the decrease of HDPE volume fraction in the blend. The 90/10 PLA/HDPE blend exhibited electrical percolation at 0.25 vol% CNT compared to 1.0 vol% for the 10/90 PLA/HDPE blend. At 7.0 vol% CNT and higher, the EMI SE of the 50/50 PLA/HDPE blend showed marginally higher SE than the 90/10 PLA/HDPE blend. The EMI SE was found to be a function of the composite’s electrical resistivity and microstructure.

Effect of carbon nanotubes content on compressive properties and deformation behaviors of aluminum matrix composite foams

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams.

Effects of PVA fibers and multi-walled carbon nanotubes reinforcement on uniaxial compression fatigue properties of Engineered geopolymer composites

As a new type of green and environmentally friendly cementing material, engineered geopolymer composites (EGC) have broad application prospects. In this study, uniaxial compression fatigue tests were conducted to investigate the fatigue properties of geopolymer material. A total of 137 samples were tested to investigate the effects of carbon nanotubes content, polyvinyl alcohol (PVA) fibers volume content, and maximum stress level on the fatigue life and deformation of geopolymers. The results showed that the fatigue life of geopolymers obeys Weibull distribution, and PVA fibers and multi-walled carbon nanotubes (MWCNTs) achieved multiscale enhancement of the fatigue life by up to 16.34 times. The total strain accumulation, residual strain, and fatigue stiffness of the geopolymers under fatigue loading exhibited a three-stage evolution rule, with stability within the secondary creep branch. In the process of EGC production, the innovative adoption of optimized MWCNTs surface modification and dispersion strategies improved the uniformity of MWCNTs distribution in the matrix. Scanning electron microscopy (SEM) confirmed the hybridization of MWCNTs and PVA fibers at the microscopic level, which can achieve multi-scale enhancement of geopolymers. This study successfully optimized the content of MWCNTs and PVA fibers, further expanding the application range of composite materials.

Fabrication and electromagnetic absorbing properties of CNTs modified PDCs-SiOC

To enhance dielectric properties and electromagnetic (EM) absorption performances of polysiloxane (PSO) derived SiOC ceramics, carbon nanotubes (CNTs) as modifiers were introduced by the pyrolysis of CNTs/PSO mixtures. Effects of CNTs content and heat treatment temperature on the microstructure evolution and dielectric properties of CNTs/SiOC composites are studied. Results show that CNTs can accelerate the crystallization of SiOC and such a role becomes more significant with CNTs content and heat treatment temperature increasing, inducing the formation of large-sized SiC nanocrystals and SiC nanowires. Foreign CNTs, crystalline SiC phases, and amorphous SiOC matrix construct a typical A/B/C EM absorption structure, which endows CNTs/SiOC with greatly improved reflection losses. When the CNTs content is 2 wt%, CNTs/SiOC with a thickness of 2.9 mm treated at 1400 °C reaches a minimum reflection coefficient of −59 dB at 9.6 GHz and has an effective EM absorption bandwidth of 3.5 GHz in the X-band.

Extrusion foaming of multiphasic polyethylene/ethylene-vinyl acetate copolymer/carbon nanotube mixtures: Tailoring foam properties by selective localization of nanoparticles

Semi-conductive foams based on low-density polyethylene/ethylene-vinyl acetate copolymer (LDPE/EVA) blends in the presence of carbon nanotubes (CNTs) were prepared using a twin-screw extrusion process. The effects of CNTs content and localization state in the binary mixture on the physical and structural properties of LDPE/EVA/CNT foams were investigated. The results confirmed that the void fraction, cell density, bubble size and cell size distribution of foams are optimal against CNT loading. The lightest LDPE/EVA/CNT foam was obtained by the CNT localization in the LDPE matrix. This foam containing 2.5 phr of CNT had smaller cells and more uniform cell size comparing to the pure blend foam. The cell density of this foam was 1.598 × 106 cells/cm3, which is much larger than that for the blend foam, 8.64 × 105 cells/cm3. However, the CNT localization state in the dispersed EVA domains resulted in lower void fractions and cell densities comparing with the LDPE/EVA blend foam. The findings clarify the profound impact of the nanofiller localization state on the foam properties of the binary polymeric systems. Light semiconductive LDPE/EVA foams with small cells, uniform cell size and high cell densities were achieved by localizing and dispersing the CNT nanoparticles in the LDPE matrix phase.

Effect of CNT content and size on the high-temperature particle-erosion resistance of ablative materials for thermal protection systems

Advanced spacecraft development requires high-performance thermal protection systems composed of materials with high particle-erosion resistance. In this study, a particle-erosion test motor was designed to produce a high-temperature particle jet. Subsequently, the effects of carbon nanotube (CNT) content and size on the particle-erosion resistance of ethylene propylene diene monomer (EPDM) composites were analyzed. Composites with an optimum CNT content exhibited the lowest ablation rates; extremely high or low CNT contents increased the ablation rate. Furthermore, the charring rate of the composites with long CNTs were 78.0% and 43.6% lower than those with the baseline-formula composition and those containing conventional CNTs, respectively. Here, the influence of CNT content and size on the particle-erosion resistance of EPDM composites was analyzed from the perspective of the thermal stability of the composites, as well as the char-layer characteristics and vapor deposition.

Additive manufacturing of carbon nanotube/polylactic acid films with efficient electromagnetic interference shielding and electrical heating performance via fused deposition modeling

In the wake of developments in 5th generation mobile communication technology and Internet of Things, traditional electromagnetic interference (EMI) shielding materials are not satisfied with the booming demand of suppressing electromagnetic pollution. In view of the characteristics of low-cost, easy-operating and functional materials applicability of fused deposition modeling (FDM), in this work, a multifunctional carbon nanotube (CNT)/ polylactic acid (PLA) film with electromagnetic shielding and electric heating properties was prepared by using FDM process. The effects of CNT content, FDM-printed film thickness, and FDM process parameters on electromagnetic shielding performance were studied. The results indicate that the additions of CNT increase the EMI shielding performance by forming the conductive paths in the CNT/PLA FDM-printed films. The EMI shielding value of the 4 wt% CNT/PLA film with a thickness of 4 mm is 68 dB at 12.3Ghz. In addition, the improved electrical conductivity provides the good electric heating performance of the CNT/PLA film. At a safe voltage (16 V), the heating temperature of the 4 wt% and 8 wt% CNT/PLA films reached 67.8 °C and 139 °C, respectively. The good repeatability and stability of CNT/PLA films for electric heating were verified. The obtained CNT/PLA FDM-printed films have excellent electromagnetic shielding and low-voltage electric heating properties by adjusting the CNT contents and the FDM process parameters, which expands the application potential of EMI shielding materials and FDM technology.

Effect of carbon nanotube content on the microstructure and mechanical properties of CNTs/TiAl alloys

TiAl alloys are ideal high-temperature structural materials for aerospace applications. However, their ductility, bending strength and machinability are poor at room temperature, thus severely limiting their practical application. In this study, carbon nanotubes (CNTs) were used as additives, and Ti–48Al–2Cr–8Nb was used as the original powder to prepare CNTs/TiAl alloys by employing spark plasma sintering. The effects of different CNT contents on the microstructure, hardness and bending strength of CNTs/TiAl alloys were investigated. The results indicated that CNTs reacted with the matrix to generate granular TiC and Ti2AlC reinforced phases stacked into bands at the grain boundaries, limiting grain growth. The Ti2AlC phase content increased with increasing CNT content. When the contents of the TiC and Ti2AlC phases were high, agglomeration occurred, leading to defects such as pits and cracks on the surface, which explains the weakened mechanical properties of the CNTs/TiAl alloys at room temperature. When the CNT content was 0.4 wt%, the average grain size was approximately 32 μm under the effects of fine grain strengthening and second phase strengthening. Moreover, the mechanical properties of the composite were the best at room temperature. The Vickers hardness and bending strength at room temperature were 377 HV and 879 MPa, respectively, and the compressive strength and strain were 2554 MPa and 31.86%, respectively. The fracture mode was mainly transgranular.

CNTs boosting superior cycling stability of ZnFe2O4/C nanoparticles as high-capacity anode materials of Li-ion batteries

In recent years, bimetallic oxides have been widely researched as promising anode materials of Li-ion batteries due to their superior electrochemical capacities compared with single transition metal oxides. However, the low interior conductivity and volume change upon cycling result in poor cycling stability. Here, carbon nanotubes (CNTs) have been employed in a solvothermal method to successfully boost the high capacity and superior cycling stability of ZnFe2O4/C nanoparticles. The effect of CNTs content on the structure, morphology, and electrochemical property of the composite has been investigated. At 200 mA g–1, ZnFe2O4/C/CNTs composite shows a high first discharge specific capacity of 1375.7 mAh g–1. After 100 cycles, the specific capacity can be still maintained at 1430.4 mAh g–1. The excellent electrochemical performance of ZnFe2O4/C/CNTs is attributed to the protective shell of carbon coating layer and three-dimensional channel constructed by high-conductive CNTs, which can alleviate volume change upon cycling and accelerate the transfer of electrons and lithium ions. This work provides a feasible idea for improving the properties of carbon-modified bimetallic oxide anode materials of secondary rechargeable batteries.

Effect of Carbon Nanotube Content and Mechanical Milling Conditions on the Manufacture of AA7075/MWCNT Composites

Aluminium matrix composites (AlMCs) of AA7075 aluminium alloy reinforced with 0.5 and 1 wt.% multiwall carbon nanotubes (MWCNTs) were fabricated with powder metallurgy techniques using three different mechanical milling strategies, varying the milling energy and the stage in which the reinforcements were added to the pre-alloyed matrix powders. In this paper, we focus on the influence of these parameters on the dispersion of MWCNTs. Characterization of the obtained composite powders by X-ray diffraction and scanning electron microscopy showed that the evolution of the particle size and morphology of the composite powders is influenced by milling conditions and MWCNT content; however, under the conditions tested in this study, there were no significant differences in crystallite size and lattice strain. The best distribution of the reinforcements was obtained after milling 7075 powders and MWCNTs in a high-energy cycle (HEBM), varying the rotation speed between 1200 and 1300 rpm. Raman spectroscopy was used to assess the damage induced by the milling process in the nanotubes, and no reaction products were detected under any of the tested conditions. Nanoindentation tests were performed to measure the elastic modulus and hardness of the composite powders, revealing that the best mechanical behaviour was achieved by the 7075-0.5 wt.% MWCNT composites obtained by the HEBM route.

Effect of Carbon Nanotube Content in ZnO/Carbon Nanotube Based Photoanode for Dye Sensitized Solar Cells

ZnO/Carbon Nanotube (CNT) nanocomposite is explored as a ZnO based photoanode which helps in the performance enhancement of DSSC. The ultra-sonication followed by magnetic stirring of ZnO nanopowders with 0.01, 0.05, 0.1, 0.2, to 0.3 wt% of microwave irradiated functionalized CNTs are experimentally done to obtain ZnO/CNT nanocomposite. The effect of CNT loading on ZnO are analysed by the morphological and optical characterization studies. DSSCs are fabricated with ZnO/CNT nanocomposite with different weight ratios of CNT as photoanode material. It has been observed that the performance of DSSC is greatly influenced by the varying amount of CNTs in ZnO/CNT. An optimum content of 0.1 wt% of CNT exhibits maximum power conversion efficiency of 2.9%. The improvement in efficiency is mainly due to the increased dye adsorption and enhanced visible light absorption provided by the ZnO/CNT nanocomposite. The optimization studies on photoanode thickness are also conducted to analyse its effect on output performance. An optimum two layer coating of 0.1 wt% ZnO/CNT could improve the efficiency to about 3%. The increased number of layer coatings of ZnO/CNT hinders the light absorption due to the blocking effect of thicker CNT layers.

Correction to: Simultaneous Effects of Carbon Nanotube Content and Diameter Size on Microstructure and Mechanical Properties of Double Pressed Double Sintered Al/Carbon Nanotube Nanocomposites

Correction to: Simultaneous Effects of Carbon Nanotube Content and Diameter Size on Microstructure and Mechanical Properties of Double Pressed Double Sintered Al/Carbon Nanotube Nanocomposites

Simultaneous Effects of Carbon Nanotube Content and Diameter Size on Microstructure and Mechanical Properties of Double Pressed Double Sintered Al/Carbon Nanotube Nanocomposites

Simultaneous Effects of Carbon Nanotube Content and Diameter Size on Microstructure and Mechanical Properties of Double Pressed Double Sintered Al/Carbon Nanotube Nanocomposites

Improvement of thermal insulation and compressive performance of Al2O3–SiO2 aerogel by doping carbon nanotubes

Carbon nanotubes (CNTs) have attracted significant attention from researchers due to their high specific strength and good extinction properties. In this study, Al2O3–SiO2 aerogel composites doped with 0–1.0 wt% CNTs were prepared by sol-gel and supercritical drying technologies, and the effects of CNT content on their microstructure, mechanical properties, heat insulation properties, and theoretical thermal conductivity were examined. With an increase in the CNT amount, the specific surface area and pore diameter of the aerogel composites decreased, while their compressive properties were enhanced. The obtained results revealed that the 1.0 wt% CNT-doped Al2O3–SiO2 aerogel composite exhibited the best comprehensive properties, while its thermal conductivity of 0.178 W/mK at 1000 °C was 15% lower than that of pure aerogel. In addition, the theoretical thermal conductivities of all samples were calculated in the temperature range of 25–1000 °C. This study explained that the addition of CNTs can significantly improve the comprehensive properties of Al2O3–SiO2 aerogel composites.

Effect of Carbon Nanotubes Content on Microstructure and Properties of Laser Cladded Ni-Based Composite Coating

Effect of Carbon Nanotubes Content on Microstructure and Properties of Laser Cladded Ni-Based Composite Coating

Micromechanical technique based prediction of effective properties for hybrid smart nanocomposites

The domain of carbon nanotube (CNT) reinforced composites is a colossal and convoluted area of research. The modeling of composite materials under deformation plays a vital role in structural design. A new model that comprises CNT and piezoelectric fibers reinforced in a hybrid smart composite has been proposed, and its effective properties are determined. The resulting composite can be regarded as a cylindrical composite with continuous parallel PZT fiber embedded inside the CNT-reinforced hybrid nanocomposite. The strength of a material based on the micromechanics technique is used to evaluate the proposed hybrid smart nanocomposite's effective elastic and piezoelectric properties. The results illustrate that the introduction of CNTs as reinforcing fibers in the proposed composites has significantly improved the effective elastic and piezoelectric properties. The effects of CNT content and volume fractions were investigated in a hybrid smart nanocomposite.

Effect of carbon nanotubes content on microstructure and properties of WC/Ni laser cladding coatings

ABSTRACT To enhance the mechanical properties of Ni–WC coatings, the carbon nanotubes were used as reinforced materials by laser cladding. Optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to investigate the effect of CNTs content on the phase composition and microstructure. The microhardness and wear resistance were measured by Vickers hardness testing and friction wear testing. Experimental results showed that the new phases Cr2Fe14C are found in the coatings with CNTs, the grain size is finer than that of the coating without CNTs. The microhardness and wear resistance of the coatings with CNTs content ranging from 0 to 5 wt-% present increase initially and then decrease trend. The coatings with 3 wt-% CNTs have the highest microhardness and wear resistance, which proved that the appropriate amount of CNTs addition is 3 wt-%.

Hybrid Nanocomposites of Cellulose/Carbon-Nanotubes/Polyurethane with Rapidly Water Sensitive Shape Memory Effect and Strain Sensing Performance.

In this work, a fast water-responsive shape memory hybrid polymer based on thermoplastic polyurethane (TPU) was prepared by crosslinking with hydroxyethyl cotton cellulose nanofibers (CNF-C) and multi-walled carbon nanotubes (CNTs). The effect of CNTs content on the electrical conductivity of TPU/CNF-C/CNTs nanocomposite was investigated for the feasibility of being a strain sensor. In order to know its durability, the mechanical and water-responsive shape memory effects were studied comprehensively. The results indicated good mechanical properties and sensing performance for the TPU matrix fully crosslinked with CNF-C and CNTs. The water-induced shape fixity ratio (Rf) and shape recovery ratio (Rr) were 49.65% and 76.64%, respectively, indicating that the deformed composite was able to recover its original shape under a stimulus. The TPU/CNF-C/CNTs samples under their fixed and recovered shapes were tested to investigate their sensing properties, such as periodicity, frequency, and repeatability of the sensor spline under different loadings. Results indicated that the hybrid composite can sense large strains accurately for more than 103 times and water-induced shape recovery can to some extent maintain the sensing accuracy after material fatigue. With such good properties, we envisage that this kind of composite may play a significant role in developing new generations of water-responsive sensors or actuators.