Addition Of Multi-walled Carbon Nanotubes Research Articles

Wear debris analysis of Al-Si/MWCNT nanocomposite during dry sliding wear tests

Abstract This study demonstrates the enhancement of wear resistance achieved by incorporating multi-walled carbon nanotubes (MWCNTs) in LM6 aluminum alloy to form nanocomposites. Experiments on wear resistance study were performed at different test parameters for various compositions of MWCNT in LM6 alloy. The size and nature of debris obtained post-experiments were significantly dependent on the MWCNT contents. Wear resistance was found to increase with increase in the MWCNT fraction in the nanocomposite. The worn surface and the shape as well as the size of the debris were studied under scanning electron microscopy (SEM). Energy-dispersive spectroscopy (EDS) analysis of the worn surfaces was used to detect and measure the constituents present in the debris. SEM micrographs of the nanocomposites show that the features of the wear debris are completely altered when MWCNT was added. Further, the wear mechanism underwent a change from oxidative in LM6 to that of ploughing in LM6 nanocomposite. The recorded surface roughness values also confirm the above findings and show significantly reduced surface roughness (~82%, 0.75 wt.% MWCNT). These results clearly demonstrate the advantage of the addition of MWCNT for enhancing resistance to wear in LM6 alloys.

Nerve tissue regeneration based on magnetic and conductive bifunctional hydrogel scaffold

The growth of neurons is often influenced by magnetic and electrical physical factors, and there is more and more research focused on designing a magnetic and conductive engineering scaffolds for nerve injury repair. In this study, electrospun poly lactic-co-glycolic acid (PLGA) fibers containing Fe3O4 magnetic nanoparticles were cryo-cut into magnetic short fibers (MSFs) and subsequently incorporated into sodium alginate (SA)/carboxymethyl chitosan (CMCS) hydrogel along with the addition of multi-wall carbon nanotubes (MWCNTs). MSFs can also achieve alignment by external magnetic fields within the hydrogel to construct magnetic and conductive bifunctional MSF/MWCNT/SA/CMCS hydrogel with anisotropic structure. The magnetic-conductive bifunctional hydrogel exhibited good magnetic responsiveness, electrically active and mechanical property, in which both conductivity and mechanical property increased with the enhancement of MWCNTs contents. Notably, appearing of aligned structure significantly promoted the mechanical property of MSF/SA/CMCS hydrogel. The MSF/SA/CMCS hydrogel with aligned structure also facilitated greater primary neuron cells proliferation than random ones. Compared with individual magnetic or conductive hydrogel, there was significant increase of cell viability in the primary cultured cortical neurons on MSF/MWCNT/SA/CMCS hydrogel with aligned structure. Simultaneously, electrical stimulation (ES) combined with magnetic stimulation (MS) delivered via magnetic and conductive bifunctional MSF/MWCNT/SA/CMCS hydrogel with aligned structure produced a better effect on promoting neuronal growth compared with individual ES or MS. Besides, hot plate measurement indicated that MSF/MWCNT/SA/CMCS hydrogel with aligned structure and MS significantly decreased the mice licking latency after sciatic nerve injury. Animal behavior studies confirmed the protective role of synergistic MS with magnetic hydrogel. Such hydrogel scaffolds have long term potential for nerve tissue regeneration.

Characterization and Evaluation of Mechanical Properties of Carbon Nanotube Filler Epoxy Composite

The outstanding mechanical properties of carbon nanotubes (CNT) have made them the focus of extensive investigation. To characterize and study the effects of the different volume fraction of multi walled carbon nanotubes (MWCNTs) on the mechanical properties of the nanocomposites attempted. The purpose of this work is to use experimental techniques to ascertain the mechanical characteristics of the nanocomposite. Tests on mechanical tensile strength were conducted to see how the MWCNT filler content affected the reinforced epoxy nanocomposite. The result of altered percentage of MWCNTs on the mechanical properties of the composites had been inspected. Results showed that 0.2 wt% MWCNT addition has the best effect on the mechanical properties of the matrix.

Investigation of microstructure evolution and electromagnetic shielding mechanism of absorbed MWCNTs-FeCo composites by one-step in situ deposition using high-speed laser cladding

Electromagnetic shielding materials can inhibit or reduce the harm of electromagnetic radiation and have become an important means to protect against electromagnetic pollution. In order to overcome the inconveniences of in situ or conformal manufacturing on the specific equipment, and the resulting assembly errors lead to the reduction of electromagnetic interference shielding effectiveness (EMI SE). As a new technology, high-speed laser cladding can directly design multi-walled carbon nanotubes (MWCNTs)-FeCo alloy composites as absorbents, and it is the first time to realize the rapid manufacturing of electromagnetic shielding materials by one-step in-situ deposition without adding auxiliary materials. According to the temperature field and stress field, it is found that the through-crack defects of electromagnetic shielding coating mainly resulted from the residual stress concentration of microcracks near the bottom fusion line. When the cladding strategy is 1600 W power deposition after preheating at 400 °C, a high-quality cladding layer can be obtained. When the addition of MWCNTs is 1.5 wt%, the material exhibits good electromagnetic shielding performance under the synergistic effect of dielectric loss, conductivity loss, and magnetic loss. And the average EMI SE is 23 dB in the range of 2-18GH. The research shows that high-speed laser cladding can simultaneously meet the requirements of flexible material design and efficient preparation, which realizes the integration of electromagnetic shielding material design and manufacturing.

Effect of nano-Ag addition on the superconducting properties of MWCNT doped magnesium diboride superconductor

Bulk MgB2 superconductor added with nano silver (Ag), multiwalled carbon nanotube (MWCNT) and both the added (i.e., nano-Ag and MWCNT) samples were synthesized. The influence of nano-Ag and MWCNT addition on the structural and superconducting properties were studied. The XRD analysis confirms the formation of hexagonal MgB2 superconductor. Microstructural studies of all the synthesized samples are carried out by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The superconducting properties such as critical temperature (Tc), magnetic critical current density (Jc), irreversibility field (Birr) and flux pinning properties of all the synthesized samples were investigated at 10 K and field up to 7 T. Nano Ag added MWCNT doped MgB2 shows maximum enhancement in the critical current density i.e., 5.83 × 104 A/cm2 at 5 T and 10 K.

Muti-Filler Composites Reinforced with Multiwalled Carbon Nanotubes and Chopped Carbon Fibers for the Bipolar Plate of Fuel Cells

To improve the conductivity and flexural strength of bipolar plates for proton-exchange membrane fuel cells, multi-filler-reinforced composites were prepared using graphite, multiwalled carbon nanotubes (MWCNTs), chopped carbon fibers (CCFs), and phenolic resin (PF). The effects of CCF content (0–6 wt.%) and MWCNT content (0–8 wt.%) on the flexural strength, electrical conductivity, interfacial contact resistance (ICR), density, hydrophobicity, and corrosion behavior of the composites were investigated. Results showed that the addition of a small number of CCFs (≤4 wt.%) effectively improved the flexural strength but slightly reduced the electrical conductivity and increased the ICR of the graphite/PF/CCF composites. Further addition of MWCNTs (≤6 wt.%) significantly improved the electrical conductivity and ICR of the graphite/PF/CCF/MWCNT composites, while maintaining high flexural strength. When the composites were filled with 4 wt.% CCFs and 2 wt.% MWCNTs, their electrical conductivity, flexural strength, ICR under 1.38 MPa, and contact angle were 272.8 S/cm, 43.1 MPa, 1.19 mΩ·cm2, and 101.5°, respectively. Compared to unreinforced composites, the electrical conductivity was reduced by 27.2%, the flexural strength was increased by 65.1%, and the composite possessed favorable hydrophobicity as well as corrosion behavior. This work reveals that CCFs and MWCNTs can effectively cooperate to improve composites’ electrical and flexural strength properties.

Effectiveness of multi‐walled carbon nanotube on the improvement of tensile, flexural, and low‐velocity impact properties of hybrid Kevlar/carbon fiber reinforced epoxy‐based composites

AbstractIn this study, the effects of hybridizing carbon fibers with Kevlar fibers and incorporating multiwalled carbon nanotube (MWCNT) particles on low‐velocity impact, tensile, and flexural performance were evaluated experimentally. A manual lay‐up procedure followed by vacuum bag molding was used to construct hybrid composites (carbon and Kevlar) with and without MWCNTs, as well as hybrid composites with varying MWCNT weight ratios of carbon and Kevlar fiber reinforcements. When 0.1 wt% of MWCNT was added to the epoxy to enhance absorbed energy and peak load, the maximum improvements observed were 31% and 28%, respectively. The addition of MWCNTs by 0.5 wt% to the epoxy enhanced the flexural strength and flexural modulus by 66% and 41%, and by 5% with 0.1 wt% and 12.3% with 0.5 wt% MWCNT for tensile strength and tensile modulus, respectively. These improvements were observed in both tensile strength and tensile modulus. As for (C5K10C5), the maximum improvements in absorbed energy and peak load were observed to be 11.2% and 31%, respectively, corresponding to a 0.1 wt% MWCNT addition, whereas the maximum improvement in flexural strength and flexural modulus was 12.28% and 44%, respectively, with a 0.1 wt% MWCNT. These improvements in mechanical properties are primarily attributed to the enhanced stress transfer properties from fibers and nanoparticles to the matrix. This enhancement is a result of the strong interfacial interactions between epoxy and MWCNT nanoparticles.Highlights MWCNT inclusion effects on mechanical properties of carbon/Kevlar hybrid composites. MWCNT inclusion effects on low‐velocity impact properties of Carbon/Kevlar hybrid composites. The effects of Kevlar and carbon stacking sequence with MWCNT incorporation were investigated.

Experimental investigation of thermal energy storage in shell-and-multi-tube unit with nano-enhanced phase change material

This paper deals with thermal energy storage with use of nanoparticle enhanced phase change material in shell-and-multitube unit. The experiments are conducted under atmospheric pressure. Paraffin wax and two different fatty acids are used as base phase change material. Graphite and multi-walled carbon nanotubes serve as nanoparticles. Graphite nanoparticles are tested at the concentrations of 0.1 %, 1 % and 5 % by weight, while multi-walled carbon nanotubes only at 0.1 %wt. Ultrasonic vibration and homogenizer are used in order to stabilize the dispersion of the nanoparticles. Polyvinylpyrrolidone surfactant is used to stabilize the suspension and the tested nano-enhanced phase change material exhibit satisfactory stability. Experimental measurements are performed for a bundle of 7 tubes with outside diameter of 6 mm in a staggered arrangement and a pitch ratio of 4.5. It is found that, regardless of the tested base phase change material, the addition of graphite nanoparticles with mass concentration of 0.1 % does not significantly affect the charging and discharging times compared to base phase change material. The differences in charging and discharging times did not exceed 11 %. For a graphite nanoparticles mass concentration of 5 %, an increase in the charging time by up to 21 % and a reduction in the discharging time by 24 % was observed, depending on the type of base phase change material. An addition of multi-walled carbon nanotubes with mass concentration of 0.1 % shows an increase in charging time regardless of the type base phase change material up to 144 % with negligible influence on the discharging time. It was also observed that adding a surfactant to the produced nano-enhanced phase change material results in a reduction in charging time by up to 83 % depending on the type of base phase change material.

Influence of carbon nanotubes on the morphology of Cu6Sn5 in Cu/(Sn–Ag–Cu) solder joints

This study delves into the intricate interaction between multi-walled carbon nanotubes (MWCNTs) and the Sn–Ag–Cu solder system, highlighting its relevance in lead-free soldering applications. Reflow and isothermal aging induce the formation of intermetallic layers at the joint interface, including Cu6Sn5, Cu3Sn, and irregularly shaped Ag3Sn particles. The addition of MWCNTs leads to the flattening of Cu6Sn5 grains, restraining their growth and potentially improving mechanical strength. Notably, MWCNTs exhibit a relatively high affinity with Ag3Sn. Grain size distribution analysis indicates that MWCNTs reduce particle size, effectively suppressing intermetallic compound growth. Over time, grain size increases due to simultaneous coarsening and growth during isothermal aging. In the growth kinetics analysis of intermetallic compounds in SAC305-MWCNTs solder joints, stable behavior is observed for Cu3Sn growth, driven by solid-state diffusion between Cu6Sn5 and Cu. In contrast, Cu6Sn5 exhibits significant variations in growth behavior with temperature changes. Furthermore, the evaluation of activation enthalpy for Cu3Sn growth in the Cu/(SAC305-MWCNTs) and Cu/SAC305 diffusion couples reveals similar n and k values of the power function for the layer growth, indicating a comparable rate-controlling process for Cu3Sn growth. The presence of MWCNTs in the solder does not significantly influence the rate-controlling process or activation enthalpy for Cu3Sn growth, contrasting with the observed effects on Cu6Sn5 growth. This study provides valuable insights into the interactions within the SAC305-MWCNTs solder system, offering significant implications for lead-free soldering applications.

Characterization of airborne dust emissions from three types of crushed multi-walled carbon nanotube-enhanced concretes

Dispersing Multi-Walled Carbon Nanotubes (MWCNTs) into concrete at low (<1 wt% in cement) concentrations may improve concrete performance and properties and provide enhanced functionalities. When MWCNT-enhanced concrete is fragmented during remodelling or demolition, the stiff, fibrous and carcinogenic MWCNTs will, however, also be part of the respirable particulate matter released in the process. Consequently, systematic aerosolizing of crushed MWCNT-enhanced concretes in a controlled environment and measuring the properties of this aerosol can give valuable insights into the characteristics of the emissions such as concentrations, size range and morphology. These properties impact to which extent the emissions can be inhaled as well as where they are expected to deposit in the lung, which is critical to assess whether these materials might constitute a future health risk for construction and demolition workers. In this work, the impact from MWCNTs on aerosol characteristics was assessed for samples of three concrete types with various amounts of MWCNT, using a novel methodology based on the continuous drop method. MWCNT-enhanced concretes were crushed, aerosolized and the emitted particles were characterized with online and offline techniques. For light-weight porous concrete, the addition of MWCNT significantly reduced the respirable mass fraction (RESP) and particle number concentrations (PNC) across all size ranges (7 nm – 20 μm), indicating that MWCNTs dampened the fragmentation process by possibly reinforcing the microstructure of brittle concrete. For normal concrete, the opposite could be seen, where MWCNTs resulted in drastic increases in RESP and PNC, suggesting that the MWCNTs may be acting as defects in the concrete matrix, thus enhancing the fragmentation process. For the high strength concrete, the fragmentation decreased at the lowest MWCNT concentration, but increased again for the highest MWCNT concentration. All tested concrete types emitted <100 nm particles, regardless of CNT content. SEM imaging displayed CNTs protruding from concrete fragments, but no free fibres were detected.

Physical and Chemical Characterization of Collagen/Alginate/Poly(Vinyl Alcohol) Scaffold with the Addition of Multi-Walled Carbon Nanotube, Reduced Graphene Oxide, Titanium Dioxide, and Zinc Oxide Materials

Physical and Chemical Characterization of Collagen/Alginate/Poly(Vinyl Alcohol) Scaffold with the Addition of Multi-Walled Carbon Nanotube, Reduced Graphene Oxide, Titanium Dioxide, and Zinc Oxide Materials

Effect of Multi-walled Carbon Nanotube and Polyethylene Glycol Addition in Nanofluid Quench Medium for Steel Heat Treatment Application

Effect of Multi-walled Carbon Nanotube and Polyethylene Glycol Addition in Nanofluid Quench Medium for Steel Heat Treatment Application

Investigation of thermoelectric properties of high concentration PEDOT: PSS inks doped with graphene and multi-walled carbon nanotubes

The use of wearable technologies in various aspects of life, particularly in health and entertainment, is experiencing a remarkable increase. This intensity of usage brings with it the energy needs of these devices. Polymer-based thermoelectric generator solutions are one of the most emphasized issues in energy harvesting applications and stand out as a solution method. In this study, we introduce a high-concentration poly(3,4-ethylenedioxy-thiophene): polystyrene sulfonate (PEDOT: PSS)-based conductive polymer ink, which has been doped with graphene and multi-walled carbon nanotubes (MWCNT) for thermoelectric applications. We also explore the film properties derived from this ink. The fabrication process involves cryogenic freezing, lyophilization, and re-dispersion of a mixture of water and dimethyl sulfoxide (DMSO) with a commercial PEDOT: PSS aqueous solution, followed by the addition of specific additives. These added compounds have led to a significant increase in electrical conductivity, resulting in materials with high electrical conductivity levels ranging from 100 to 200 S/cm. Remarkably, even after subjecting the material to 100 bending cycles, no significant change in electrical conductivity was observed. All the materials produced exhibited p-type semiconductor properties, and the high concentration of PEDOT: PSS, along with the addition of graphene and multi-walled carbon nanotubes, notably enhanced the Seebeck coefficient, reaching a maximum of 25 μV K⁻1.

Mechanical and electromagnetic interference shielding properties of natural fiber reinforced polymer composite with carbon nanotubes addition

AbstractMechanical and electromagnetic interference (EMI) shielding properties are investigated for developed synthesized green composite. The varying content of kenaf fiber‐reinforced high‐density polyethylene (HDPE) composite has been fabricated using microwave‐assisted compression molding techniques with and without the addition of multi‐walled carbon nanotubes (MWCNTs). X band range has been used for EMI shielding characterization. Optimization for mechanical strength has been done using tensile test, impact test, and translaminar fracture toughness test. Fractography by scanning electron and optical microscopy concluded that interfacial adhesion between kenaf fiber and HDPE matrix and the degree of ductility of the matrix are primary governing factors for change in mechanical properties. The differential scanning calorimetry confirmed no change in the degree of crystallization of the matrix with the addition of MWCNTs. Composite with EMI shielding effect above 30 dB along with superior mechanical properties is obtained at 16% (v/v) kenaf fiber content with the addition of 5% (wt.) conductive MWCNTs for possible application in electronic equipment casing, overhead bin, or unmanned aerial vehicles.

Enhancing bond performance: Carbon fiber reinforced polymer bar interaction with multi-walled carbon nanotubes cementitious composites in chloride-exposed conditions

A number of studies have been conducted on strengthening structures using carbon fiber reinforced polymers (CFRP) and improving the performance of cement fillers using multi-walled carbon nanotubes (MWCNT). In this study, bond characteristics of CFRP bars to MWCNT cementitious composites is investigated in chloride environment. The bonding advantage of CFRP bars and MWCNT cement filler is due to the mechanical properties of MWCNT and the ability to utilize the corrosion resistance provided by CFRP. This enables highly durable composites that can resist corrosion in chloride-rich environments. A total of 36 pullout (PO) tests were performed on CFRP bars set into MWCNT cementitious composites. Mercury Intrusion Porosimetry (MIP) test and field-emission scanning electron microscopy (FE-SEM) confirmed a decrease in porosity upon addition of MWCNTs. MWCNTs filled the pores of cement with nanoscale particles and increased the bond area of the cement composite with CFRP bar. The reduction in porosity between cement and aggregate not only enhanced strength but also improved chloride resistance. However, agglomeration began at 1.0-wt% concentration owing to van der Waals forces. The results revealed that the 0.5-wt% MWCNT cementitious composite with CFRP bars had the highest bond strength in a chloride environment.

Análise da redução do consumo de cimento Portland por meio da utilização de nanotubos de carbono de paredes múltiplas funcionalizados em argamassa

Abstract The use of carbon nanotubes in cementitious materials improves the mechanical properties of these composites and increases their compressive and flexural strength. The main objective of this study was to evaluate the technical feasibility of reducing the Portland cement content by using functionalized multi-walled carbon nanotubes (MWCNT) in mortar samples, using mechanical properties as parameters (compressive strength, flexural strength and modulus of elasticity). Experimental results allowed us to conclude that the addition of MWCNT in 0.1% by weight of Portland cement, to the mortar samples allowed a reduction of the Portland cement content by up to 10%, while the water/cement ratio remained unchanged without affecting the mechanical behavior.

Molecularly imprinted polymer nanoparticle-carbon nanotube composite electrochemical gas sensor for highly selective and sensitive detection of methanol vapour.

An electrochemical gas sensor has been fabricated using molecularly imprinted polymer nanoparticles (nanoMIPs) and multiwalled carbon nanotubes on screen-printed electrodes. Methanol vapour was chosen as the target due to its toxicity as its suitability as a model for more harmful pollutant gases. The sensor functions under ambient conditions and in the required concentration range, in contrast to all previous MIP-based gas sensors for methanol. The sensitivity of the sensor was greatly improved by the addition of multiwall carbon nanotubes, resulting in a limit of detection of approximately 10 ppm. The nanoMIPs provide an inherent selectivity for the target inherent in its design. Selectivity studies were performed with structurally analogous alcohols at various concentrations, demonstrating selectivity for methanol 12.1 times that for ethanol at 2 mmol dm-3 and 4.2 times that for ethanol at 1 mmol dm-3. Interactions with isopropanol and n-propanol were found to be non-specific, and the response to water was negligible. This demonstrates an improvement over previous methanol gas sensors based on molecularly imprinted polymers. No response was observed with carbon nanotubes alone, and no selectivity was observed with non-imprinted equivalents of the nanoMIP sensor. The resulting device is by far the most practical MIP-based instrument for methanol gas sensing thus far described in the literature, being the only example capable of functioning at the necessary methanol vapour concentrations and at the required temperature and humidity. With the selectivity and sensitivity described and the simple design, the developed device provides a substantial advance in the field of molecularly imprinted gas sensors.

Study of the Effect of Multi-Walled Carbon Nanotubes on the Mechanical Properties of Poly(Vinyl Alcohol)/Polyaniline Blend Film

In this research, poly(vinyl alcohol)/polyaniline blend films were fabricated using solution casting technique with different weight ratios of PANI (2, 4, 6, 8, and 10) wt.%. The results showed that the best ratio of the polymer blend was (92% PVA/8% PANI), based on the electrical conductivity of direct current. The results showed that 8 wt.% PANI possessed the highest conductivity. Then, the composite films were prepared by adding multi-walled carbon nanotubes (MWCNT) to the optimum ratio of the polymer blend as a base material and at different weight ratios (0, 1, 3, 5, 7 wt.%). A tension device was used to examine and characterize the prepared samples. It was found that the addition of MWCNT to PVA/PANI caused an obvious decrease in elongation while there was an increase in tension strength and “Young’s modulus”. Optical microscopy results showed a good picture of the distribution of MWCNT particles for composites up to 1 wt.% MWCNT. But, some aggregations can be observed in films with 3, 5, and 7 wt.% MWCNT content.

Mechanical strength enhancement of CaZr4P6O24 ceramics with multi-walled carbon nanotubes additions

Multi-walled carbon nanotubes/calcium zirconium phosphate composite (MWCNTs/CZP) ceramics were successfully synthesized by co-precipitation to improve the mechanical strength of CZP ceramics sintered at 1100 ℃ under an argon atmosphere. The impact of the different weight percentages of MWCNTs (ranging from 0.1 to 1.0 wt%) on the structure, morphological, and mechanical strength of CZP was investigated. Microstructural analysis revealed the grain size was reduced and the surface morphology and densification were improved by the addition of MWCNTs compared to pure CZP ceramics. The flexural strength and modulus of 0.5 MWCNTs/CZP composite were measured at 91.76 MPa and 21.98 GPa, respectively, further revealing that MWCNTs had significant effects on densification and mechanical strength of CZP ceramics.

Effect of nano hybrid additives on low velocity impact responses of aramid composite plates: example of CNT and ZrO2

Aramid reinforced composites are advanced materials that are widely used in many industrial applications thanks to their combination of high strength and lightness. Nano additives are of great importance for improving the mechanical properties of aramid reinforced composites and reducing costs. In this paper, multi-walled Carbon Nanotube (CNT) and Zirconia (ZrO2) nano hybrid additives were used to determine the effect on the mechanical characterization of aramid composite plates. Therefore, low velocity impact responses of aramid fiber reinforced composites were investigated by adding ZrO2 and CNT nano hybrid additives to the Polives 701 polymer vinylester resin matrix. Low velocity impact tests were carried out at 10 J and 15 J. As a result of the experiments, the effects of nano hybrid additives on the impact absorption properties of aramid composite plates were determined. By determining the maximum force, displacement and time values, the effect of CNT and ZrO2 nano hybrid additives on the impact resistance of the composite plates was analyzed. In addition, it contributed to the development of composite materials used in industrial applications by providing information on increasing the performance of composite materials by using nano additives. As a result of this study, it was determined that the strength of the composite material increased proportionally when the CNT additive was used, and the material became embrittled when the ZrO2 additive was used.