Carbon Nanotubes Content Research Articles

Compressive performance and analytical modeling of early strength seawater sea sand engineered cementitious composites

Early strength seawater and sea sand engineered cementitious composites (ESSECC) are novel fiber-reinforced cementitious composites that exhibit strain-hardening behavior and a high early strength. The compressive properties of ESSECC with different polyvinyl alcohol (PVA) fiber content, carbon nanotubes (CNTs) content, and water–binder ratios were investigated at different curing ages in this study. Experimental evaluations were conducted to assess compressive strength, elastic modulus, Poisson's ratio, peak strain, energy dissipation capacity, toughness index, and stress-strain curves. The experimental results showed that early strength of ESSECC reached 58.0 %, 81.6 %, and 86.7 % of its 28-day compressive strength after 2 h, 3 days, and 7 days of curing, respectively. An increase in the PVA fiber volume fraction from 0 to 2 % resulted in a 32.8 % increase in average peak strain. Incorporating 0.15 % CNTs into ESSECC led to an average enhancement of compressive strength by 7.2 %. Based on these experimental results, an analytical model considering the effects of curing age and the addition of PVA fibers and CNTs was developed to describe the compressive stress–strain behavior of ESSECC. This model showed strong consistency with the experimental results.

Development of polymer/carbon nanotubes incorporated sustainable materials for manufacturing of autobrake pad

AbstractAlthough asbestos fiber is used for autobrake pad production due to its heat resistance capacity, it is associated with a challenge of health risk (cancerogenic in nature). This health risk associated with asbestos-based autobrake pads has presented polymeric materials as a better candidate for the application due to their eco-friendliness, lightweight, chemical inertness, easy of processing, etc. However, polymers are associated with low wear and low mechanical properties, which are vital properties for autobrake pads. Therefore, this study developed EP nanocomposites reinforced with a low content of carbon nanotubes (CNTs) and eggshell (ES) attached cow bone (CB) particles denoted as (ES@CB) as agro-waste/sustainable materials for the manufacturing of autobrake pads. The hybrid ternary nanocomposites were developed via solution mixing and casting. Scanning electron microscope (SEM) revealed the 1-D structure of the CNTs, and relatively spherical shapes of ES and CB particles, and microstructures of the developed nanocomposites. The nanocomposite showed a low coefficient of friction and a reduction in wear rate in the range of 1.14 × 10−4 mm3/Nm for pure EP to 5.45 × 10−6 mm3/Nm for EP/0.4wt%CNTs-10wt%ES@CB nanocomposite, while the elastic modulus and hardness increased from 1.84 GPa and 128.64 MPa for pure EP to 4.41 GPa and 252.88 MPa for EP/0.2wt%CNTs-20wt%ES@CB nanocomposite, respectively. The comparison of the wear response of the developed nanocomposites with the current asbestos-based brake pads show that the developed epoxy nanocomposites from agro-waste materials are potential option for the manufacturing of autobrake pads, which will ensure sustainability, health risk-free, and environmentally friendly.

Concurrent effect of shear flow and CNT presence on crystallization behavior and electrical properties of polypropylene based nanocomposites: A comprehensive structure-property investigation

The loading of nanoparticle in the polymer matrix affects their response to shear flows applied during the fabrication process. With this in mind, in the present study, the concurrent effect of carbon nanotube (CNT) presence and shear application on the rheological and electrical properties as well as on the crystallization behavior of polypropylene (PP) based nanocomposites has been investigated. The results of rheological analyses showed that the solid-like behavior increases in proportion to the CNT content, and a remarkable increase in the solid-like behavior is obtained at a CNT content of 2 wt%. The isothermal crystallization results corroborated that crystallization temperature increases proportionally with the CNT content, however does not change with shearing. The non-isothermal crystallization findings confirmed that crystallization kinetics promotes with increasing CNT content, and this effect becomes more pronounced with shearing. The results of thermal analysis confirmed that the melting temperature decreases slightly, and the crystallinity remains almost unchanged with increasing CNT content up to 2%. However, when the CNT content rose up to 4%, the crystallinity decreased significantly due to confined crystallization. When this nanocomposite was subjected to shearing, the crystallinity increased. The results of electrical conductivity measurement revealed that the conductivity increases with increasing CNT content, while it decreases with shearing and the vulnerability of nanocomposites to shearing decreases with increasing CNT content.

Crack Detection of Reinforced Concrete Structure Using Smart Skin.

The availability of carbon nanotube (CNT)-based polymer composites allows the development of surface-attached self-sensing crack sensors for the structural health monitoring of reinforced concrete (RC) structures. These sensors are fabricated by integrating CNTs as conductive fillers into polymer matrices such as polyurethane (PU) and can be applied by coating on RC structures before the composite hardens. The principle of crack detection is based on the electrical change characteristics of the CNT-based polymer composites when subjected to a tensile load. In this study, the electrical conductivity and electro-mechanical/environmental characterization of smart skin fabricated with various CNT concentrations were investigated. This was performed to derive the tensile strain sensitivity of the smart skin according to different CNT contents and to verify their environmental impact. The optimal CNT concentration for the crack detection sensor was determined to be 5 wt% CNT. The smart skin was applied to an RC structure to validate its effectiveness as a crack detection sensor. It successfully detected and monitored crack formation and growth in the structure. During repeated cycles of crack width variations, the smart skin also demonstrated excellent reproducibility and electrical stability in response to the progressive occurrence of cracks, thereby reinforcing the reliability of the crack detection sensor. Overall, the presented results describe the crack detection characteristics of smart skin and demonstrate its potential as a structural health monitoring (SHM) sensor.

An In Situ-Gelling Conductive Hydrogel for Potential Use in Neural Tissue Engineering.

Cerebral cavitation is usual following acute brain injuries, such as stroke and traumatic brain injuries, as well as after tumor resection. Minimally invasive implantation of an injectable scaffold in the cavity is a promising approach for potential regeneration of tissue loss. This study aimed at designing an in situ-gelling conductive hydrogel containing silk fibroin (SF), brain decellularized extracellular matrix (dECM), and carbon nanotubes (CNT) for potential use in brain tissue regeneration. Two percent w/v SF hydrogels with different concentrations of dECM (0.1%, 0.2%, or 0.3% w/v) and CNTs (0.05%, 0.1%, or 0.25% w/v) were fabricated and characterized. It was observed that with the addition of dECM, the porosity decreased, whereas swelling and electrical conductivity tended to increase. The addition of dECM also led to a faster resorption rate, but no significant change in compressive modulus. Addition of CNTs, on the other hand, led to a denser, stronger, and more regular porous structure, higher swelling ratio, faster gelation time, slower degradation rate, and a significant increase in electrical conductivity. dECM and CNTs combined together resulted in superior porosity, swelling, resorption rate, mechanical properties, and electrical conductivity compared with SF scaffolds containing only dECM or CNTs. Hydrogel samples containing 2% SF, 0.3% dECM, and 0.1% CNTs had a high porosity (58.9%), low swelling ratio (15.9%), high conductivity (2.35 × 10-4 S/m), and moderate degradation rate (37.3% after 21 days), appropriate for neural tissue engineering applications. Cell evaluation studies also showed that the hydrogel systems support the cell adhesion and growth, with no sign of significant cytotoxicity. Impact statement Tissue loss and formation of a fluid-filled cavity following stroke, traumatic brain injury, or brain tumor resection lead to sensorimotor and/or cognitive deficits. The lack of a healthy extracellular matrix in the cavity avoids the endogenous cell migration and axonal sprouting and may also worsen the secondary injuries to peri-lesional tissue. Due to the brain anatomy, simple implantation of tissue engineering scaffolds to the injured site is not possible in many cases. Therefore, the development of injectable scaffolds that support neural growth and differentiation is crucial for tissue repair or limiting the expansion of damage region.

CARBON NANOSTRUCTURES OBTAINING FROM POLYMER MATERIALS

As part of the expansion of raw material base used in the development of technological and productive methods for the synthesis of carbon nanostructures (CNS) and solving the problem of environmentally friendly and economical polymer recycling, the results of investigation of microwave (MW) catalytic pyrolysis of macromolecular compounds from the range of polystyrene, polypropylene, polyethylene terephthalate, polyvinyl alcohol are presented. The information about existing approaches to solving these problems is briefly considered, and the prospects for MW processing of polymers are shown. The process was carried out by microwave treatment of a mixture of polymer raw materials acting as a carbon donor and substances-precursors of metal catalysts – cobalt and nickel compounds, their mixtures, as well as metal iron and nickel. Graphite and carbon fiber were used as temperature regulator. Experiments have demonstrated that effective conversion of the studied compounds occurs only in the presence of MW energy absorbers-converters, regardless of the nature of metal catalyst precursor. According to electron microscopy data, the resulting materials are a mixture of carbon nanostructures of disordered morphology with the predominant content of carbon nanotubes (CNTs) in the reaction products for experiments with polystyrene, polypropylene and polyethylene terephthalate. The use of polypropylene and polyvinyl alcohol leads to the production of carbon nanostructures containing only a small amount of CNTs. X-ray phase analysis data confirm the formation of multi-walled carbon nanotubes as the main structural component of the obtained carbon nanomaterials. It has been suggested that transformation pathways of the investigated hydrocarbons are similar, despite the difference in pyrolysis temperatures, which may be related to the simultaneous processes of polymer cracking, carbonization of decomposition products and CNS synthesis due to the rapid growth of reaction mass temperature during microwave treatment. The efficiency of different precursors of catalytic systems based on transition metals in the processes examined is substantiated. It has been shown that the high carbon content in feedstock promotes the formation of carbon nanostructures, but is not decisive for carbon nanotubes obtaining. For citation: Zaritovskii A.N., Kotenko E.N., Grishchuk S.V. Carbon nanostructures obtaining from polymer materials. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 99-106. DOI: 10.6060/ivkkt.20246705.6957.

Effect of carbon nanotube content and annealing temperature on corrosion performance of carbon nanotube/Ni composite layer

Adding carbon nanotubes (CNTs) to metal composites changes their corrosion resistance, which is significantly affected by the distribution of CNTs. In this study, the effect of the content and distribution of CNTs on the corrosion resistance of composites was investigated by changing the electrodeposition process. The results indicated that could inhibit grain growth and act as an elemental channel for passivation film formation, which positively enhanced the corrosion resistance of the material. However, the annealing used to improve the bonding strength of CNTs to the matrix increased the grain size of the material, which had a weakening effect on the corrosion resistance. Using ultrasonic in electrodeposition had an obvious promoting effect on the uniform distribution of CNTs. The composites with 0.1 g/l CNT showed the best corrosion resistance after annealing for 30 min at 600 °C.

Effect of sodium dodecyl sulfate (SDS) on the co-deposition and frictional behavior of carbon nanotube/nickel composite layer

In this paper, the effects of sodium dodecyl sulfate (SDS) concentrations in the electroplating solution on the morphology, nucleation rate, nucleation mode, and frictional behavior of the CNT/Ni composite layers were investigated. The results showed that the electrodeposition of Ni was in a three-dimensional nucleation/growth mode. In addition, the x-ray diffraction (XRD) of the deposited layers showed that adding SDS changed the preferred growth direction of Ni from (2 0 0) to the (2 2 0) crystallographic plane. When the carbon nanotube (CNT) content was 0.1 g l−1, and the SDS content was 0.05 g l−1, the deposition potential was the most negative, increasing the number of Ni nucleation sites on the electrode and resulting in the grain size refinement of the deposited layer. It also reduced the friction coefficient of the composite simultaneously.

Electrical conductivity of nanofluids with single- and multi-walled carbon nanotubes. Experimental study

The object of this paper is to experimental study the electrical conductivity of nanofluids with carbon nanotubes (CNT). Nanofluids based on water, ethylene glycol and isopropyl alcohol with single-walled (SWCNT) and multi-walled (MWCNT) carbon nanotubes are considered. In some cases, surfactants were used to prepare the nanofluid. CNT concentrations varied from 0.05% to 1%. It was shown that the electrical conductivity of all nanofluids much more than that of base fluids. The influence of surfactants on the electrical conductivity of nanofluids is studied and analyzed. The use of surfactants in all cases increases the electrical conductivity of the initial base fluids. The greatest excess of the electrical conductivity was achieved when using ionic surfactants. For the first time, the electrical conductivity of nanofluids with SWCNTs and MWCNTs is systematically compared. The same base fluids are used for this. It was shown that electrical conductivity of nanofluids with SWCNTs significantly exceeds that of nanofluids with MWCNTs. The effect of aspect ratio on electrical conductivity of nanofluids with SWCNTs and MWCNTs are studied. In conclusion, the possible mechanisms of electrical conductivity of the considered nanofluids are discussed.

Review on Use of Nanomaterials in Concrete

Abstract: Various studies have highlighted the benefits of incorporating carbon nanotubes (CNTs) in concrete. They enhance compressive and flexural strength, prevent cracking, and improve durability. Different methods like sonication ensure uniform dispersion of CNTs in concrete. Additionally, research focuses on optimizing CNT concentrations to avoid adverse effects on properties like shrinkage and thermal conductivity. Overall, CNTs offer a promising solution to reinforce concrete and improve its mechanical properties effectively

Wear resistance of extruder parts in the production of polymer nanomodified products

Extrusion equipment is widely used in the production of polymer materials. One of the urgent questions that arises when studying the processes of obtaining polymer products by the extrusion method is the question of studying abrasive wear, which may depend on the efficiency of the equipment, the duration and reliability of its work. In the context of abrasive wear, the process that needs attention is the extrusion of polymer materials with carbon nanotubes. The purpose of this work is to develop a numerical method for determining the evolution of abrasive wear of the equipment of the extruder working area in the process of processing nanomodified polymer granules and determining the life cycle of this equipment with in order to increase the parameters of their durability. The specific objectives of the study include: 1) Determination of the influence of the content of CNTs in PVC on the rate of wear of the steel surface of the extruder; 2) Analysis of the dependence between friction and the content of CNTs in the polymer composite; 3) Establishing optimal extrusion conditions to minimize abrasive wear of the steel surface; 4) Comparison of simulation results with experimental data to check the reliability of the model. The work is aimed at understanding the processes that occur during the extrusion of nanocomposites and their impact on the wear resistance of equipment materials, which can contribute to the improvement of technological processes and ensure longer and more efficient operation of extruders in production conditions. It has been established that the processes of extrusion processing of polymer nanoreinforced composites can be effectively studied by developing and implementing numerical models that take into account the interaction of all physical and mechanical parameters of a representative volume of the contact zone of the equipment with the polymer and the nanotube with the adhesive layer. In this work, a model for determining the physical and mechanical properties of the interface layer between the CNT and the polymer array is constructed and implemented. The technique for determining the properties of the nanotube-polymer interface is integrated into the APROKS system for analyzing the stress-strain state of nanomodified polymer materials. Based on a multilayer isoparametric FE, a series of numerical experiments were carried out to simulate the process of abrasive wear of the material of equipment elements in the extruder working area. The possibility of a detailed study of the processes of nonlinear contact interaction of nanotubes with an interface layer with equipment elements of the extruder working area based on multilayer FE has been confirmed. Diagrams were obtained that determine the service life of equipment in the working area of the extruder depending on the volume concentration of carbon nanotubes in the polymer at different levels of operating pressure in the “nanotube – polymer – equipment” contact system. It is advisable to use the proposed methodology in the development of information support systems for the life cycle of operation of equipment in the working area of extruders intended for the production of nanomodified polymer products.

Influence of carbon nanotubes on printing quality and mechanical properties of 3D printed cementitious materials

This paper presents the impact of incorporating carbon nanotubes (CNTs) into the 3D printing of cementitious materials, along with the effective dispersion of CNTs. Compared to the control mix, adding CNTs with superplasticizer significantly enhanced the printing quality by reducing the error in height of two-layers from 38% to 30% and an 81% enhancement in the buildability. Moreover, rheology properties revealed shear-thinning behaviour with lower viscosity, resulting in improved flowability. The progressive increase in CNT concentrations up to 0.2% yielded a noteworthy improvement in the mechanical properties. At 28 days, the incorporation of 0.2% CNTs resulted in a significant increase in the flexural strength, compressive strength, and Young's modulus by 99%, 72%, and 43%, respectively, compared to the mix containing silica fume. Microstructural investigation of the CNT-cement matrix revealed nanoscale crack bridges formed by CNTs, reinforcing the cementitious material and improving its mechanical properties.

Connectivity patterns in lead-free piezocomposites: A critical analysis for 0-3 and 1-3 configurations

In the quest for eco-friendly alternatives within materials science, the development of sustainable and non-toxic piezoelectric composites is of utmost importance. This study undertakes a computational exploration to elucidate the influence of phase connectivity on the engineering performance of lead-free piezocomposites. Employing a combination of analytical and numerical methodologies, we critically evaluated various figures of merit across different microstructural configurations, juxtaposing these findings with traditional lead zirconate titanate (PZT)-based materials. Our analysis considers 0-3 and 1-3 connectivity patterns, incorporating active phases in the form of spherical particles and cylindrical fibers. We also examine the impact of carbon nanotubes (CNTs) in enhancing the polymeric matrix, which introduces the potential for network percolation and further mechanical and electrical property optimization. The study yields pivotal insights into the phase connectivity of lead-free piezocomposites, with direct implications for their application in sensing, actuating, and energy harvesting domains. We ascertain that the electromechanical performance of these composites is contingent upon the connectivity pattern and the proportion of active phase. Notably, the KNNS-BNZH & Polyethylene composite demonstrates exceptional potential in 1-3 configurations, while the BTO & PVDF composite distinguishes itself with superior dielectric and piezoelectric responses across varying volume fractions. The strategic infusion of CNTs into the PDMS matrix emerges as a significant enhancer of electromechanical attributes, albeit with performance improvements that are specific to the type of coefficient and CNT concentration. This investigation underscores the nuanced interplay between composite design and microstructural attributes, reinforcing the critical role these factors play in the advancement of effective and eco-conscious piezoelectric materials.

Three-layered PBAT/CNTs composite foams prepared by supercritical CO2 foaming for electromagnetic interference shielding

Plastic pollution and electromagnetic radiation cause serious environmental problems. Herein, biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and carbon nanotubes (CNTs) composite foams with three-layered structure for electromagnetic interference (EMI) shielding application were prepared by an environmentally friendly supercritical CO2 foaming method. For the CNTs content of 4.9 vol%, the EMI shielding efficiency (SE) of three-layered composite was 23.4 dB, which was improved by 125 % compared with that of single-layered composite with a CNTs content of 4.7 vol% owing to high conductivity in skin layer and multiple reflection between interfaces. The CNTs content in core has little effect on the EMI SE when the CNTs content in skin was 16 wt%. After foaming, SE values slightly decreased due to a decreased volume content of CNTs. However, considering the decreased density of foam, the specific EMI SE was improved by 26.2% after foaming when the CNTs content was 16 wt% in skin and 0 in core. This work provided a facile and green method for preparing lightweight EMI shielding materials.

Post-creep residual tensile properties of multi-walled carbon nanotube/epoxy nanocomposites

Epoxy resin as a thermoset polymer is vulnerable to creep loading even at room temperature due to its viscoelastic nature. This study investigated the effect of reinforcing epoxy resin with different functionalized multi-walled carbon nanotubes (MWCNT) contents on the creep response and post-creep residual tensile properties of nanocomposites. The creep tests were performed on the nanocomposite specimens containing different filler contents and the neat epoxy specimen at 40°C under a constant load level of 200 N. It was found that the nanocomposites containing 0.3 wt% MWCNTs experienced 29.6%, 69.1%, and 74.1% decreases in the elastic strain, creep strain, and steady-state creep strain rate, respectively, compared to the neat epoxy. Furthermore, the tensile strength and stiffness of the neat epoxy and nanocomposite specimens were evaluated before and after a partial creep test (at a load level of 200 N for 150 min) by conducting tensile tests. The nanocomposites containing 0.3 wt% MWCNTs demonstrated considerable improvements of 35.9%, 41.2%, 27.9%, and 28.1% in strength, residual strength, stiffness, and residual stiffness, respectively, compared to the neat epoxy. Furthermore, scanning electron microscopy assessment was utilized to investigate the fracture surfaces of the nanocomposite specimens.

Bimodal coaxial fiber sensor for simultaneous strain and temperature sensing for composite manufacturing process

Coaxial structured fibers have gained significant attention in sensor applications due to their design flexibility and ability for multifunctionality. However, the complex and thicker structure of a sensor can lead to stress concentration and signal interference when utilized for strain monitoring in composite manufacturing processes. To address this issue, we propose a bimodal coaxial fiber sensor capable of simultaneous temperature and strain measurement during composite cure and strain monitoring, while preserving the mechanical properties of the fabricated composites. To achieve bimodal sensing, we employ a multi-shell structure consisting of a multi-conductive layer with varying concentrations of multiwalled carbon nanotubes and a PEDOT:PSS layer, applied to a creep-enhanced ultra-high molecular weight polyethylene core fiber using a simple dip-coating method. The bimodal coaxial fiber sensor exhibits a high gauge factor (>4.1), stable cyclic tensile response (>1000 cycles), and linear response to stepwise temperature cycles. Moreover, the sensor demonstrates high sensing accuracy (<3% error) in cure strain monitoring and maintains the fracture toughness of the composite (<1% discrepancy) wherein it is embedded. These results confirm the significant potential of the bimodal coaxial fiber sensor for various applications in the composite industry and other fields.

Cementitious composites modified by nanocarbon fillers with cooperation effect possessing excellent self-sensing properties

Abstract The safety and durability of concrete structures are prone to damage and result in significant harm to human society. Hence, monitoring and estimating the states of concrete structures is of great significance to protecting human safety. Graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) are promising candidates to endow cementitious composites with piezoresistivity for the health monitoring of concrete structures. Therefore, the aim of this article is to explore the effect of the hybrid GNPs and CNTs on behavior of cementitious composites with cooperation effects. The cementitious composites containing the hybrid GNPs and CNTs with simplified manufacturing methods are developed first. And then, the mechanical behaviors, electrical conductivities, and piezoresistive performances of the composites are investigated systematically. Finally, the modification mechanisms are also discussed. The results proved that the electrical resistivity of the composites with the hybrid GNPs and CNT concentration of 5.0 wt% is reduced by three orders of magnitudes, and the FCR and sensitivities are reached at 36.0% and 1.1% MPa−1/177.9, respectively. Its compressive strength/elastic modulus is achieved at 73.3 MPa/16.9 GPa. Therefore, the hybrid GNPs and CNTs modified cementitious composite present great potential application in monitoring and evaluating service states of civil infrastructures.

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.

Synergistic Effect of Carbon Nanotubes, Zinc, and Copper Oxides on Rheological Properties of Fracturing Fluid: A Comparative Study

Nanomaterials play a beneficial role in enhancing the rheological behavior of fracturing (frac) fluid by reacting with intermolecular structures. The inclusion of these materials into the fluid improves its stability, increases the viscosity of polymers, and enhances its resistance to high temperature and pressure. In this investigation, multi-walled carbon nanotubes (CNTs), nano-zinc oxides (N-ZnO), and nano-copper oxides (N-CuO) have been utilized to ameliorate the rheological properties of water-based fracturing fluid. Different concentrations of these aforementioned nanomaterials were prepared to determine their effects on the rheological behavior of the fluid. The results revealed that the size of nanoparticles ranged from 10 to 500 nm, 300 nm, and 295 nm for CNTs, N-ZnO, and N-CuO, respectively. Moreover, employing CNTs exhibited a resistance of 550 cp at 25 °C and reached 360 cp at 50 °C with a CNT concentration of 0.5 g/L. In contrast, N-CuO and N-ZnO showed a resistance of 206 cp at 25 °C and significantly decreased to 17 cp and 16 cp with higher concentrations of 10 g/L and 1 g/L, respectively. Based on these findings, this study recommends utilizing CNTs to enhance fracking fluid’s chemical and physical properties, which need to be highly viscous and stable under reservoir conditions.

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.