Carbon Nanotubes Content Research Articles

Silk Nanofibers/Carbon Nanotube Conductive Aerogel.

Natural silk nanofibers (SNF) are attractive conductive substrates due to their high aspect ratio, outstanding mechanical strength, excellent biocompatibility, and controllable degradability. However, the inherently non-conductivity severely restricts the potential sensor application of SNF-based aerogels. In this work, the conductive nanofibrous aerogels with low-density achieved through freeze-drying by dispersing carbon nanotubes (CNT) into SNF suspension. The addition of CNT significantly increases the conductivity with improved mechanical properties of composite aerogels. SEM results reveal that the distinct hierarchical structure comprising micropores and nanofibrous networks within the pores is formed when CNT content reached 30%. Furthermore, increased cell viability suggested the excellent biocompatibility of SNF-CNT-based conductive aerogel for tissue-engineering applications. Subsequently, the elastic water-borne polyurethane (WPU) is incorporated to SNF-CNT system to construct aerogel with good sensing properties. The introduction of WPU demonstrates enhanced compressive performances and an exceptionally high elastic recovery ratio of 99.8%, thereby exhibiting a stable and lossless strain-sensing signal output at 5% strain. This study provides a feasible choice and strategy for exploring the potential application of SNF in functional aerogels.

Mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels based on carbon nanotube‐reinforced fungal‐carboxymethyl chitosan‐bacterial cellulose nanofibers for wearable electronics

AbstractDeveloping conductive hydrogels with both enhanced mechanical properties and superior sensing capabilities for wearable, flexible electronics remains challenging. Here, we developed mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels. These hydrogels were prepared by blending fungal‐derived carboxymethyl chitosan (FC), carboxylate‐bacterial cellulose nanofibers (CBC‐NFs), and carbon nanotubes (CNTs) within a covalently crosslinked polyacrylamide (PAM) network (CNT‐FBCNF). The resulting hydrogels showed remarkable mechanical properties due to the molecular interactions between polymer chains. The hydrogels showed a self‐recoverable property and high stability under compressive mechanical force at 40% of strain (2000 cycles). The maximum compressive load (N) of 27.8 N was obtained for the optimized hydrogel, CNT‐FBCNF (1% CNT content). This hydrogel exhibited a good conductivity of 1.3 S/m, which was attributed to the homogeneous dispersion of CNTs within the hydrogel matrix and sufficient biocompatibility with skin fibroblasts. The hydrogel also exhibited impressive performance as a strain sensor, boasting a wide strain range (10–40%), excellent stability, and repeatability. Furthermore, strategic cutting and assembly of the hydrogel generated a flexible strain sensor capable of accurately monitoring finger and thumb pressure in real‐time. This study will significantly accelerate the development of hydrogel‐based sensors within the rapidly advancing field of wearable soft electronics.Highlights CNT‐reinforced composite hydrogel was developed The optimized hydrogel showed good electrical conductivity (1.3 S/m) The optimized hydrogel showed good self‐recovery properties The optimized hydrogel exhibited impressive strain‐sensing capability between 10% and 40% strain

Enhanced thermal performance of phase change mortar using multi-scale carbon-based materials

Incorporating phase change material (PCM) into construction materials is an effective method for modifying building energy regulations throughout their service life. However, the effectiveness of PCM is constrained by its low thermal conductivity, highlighting the need for efficient enhancement methods. This study introduces thermally conductive carbon-based additions at both the nano-scale and meso-scale with different shapes, including carbon nano-tube (CNT), carbon black nano-particle (CB), and carbon fibre (CF) in PCM mortar. The mixed hydrated inorganic salt serves as the core PCM, while expanded perlite acts as the supporting material for the stable PCM composite, based on the presented research. The multi-scale additions establish thermal conduction pathways that improve temperature regulation performance. The modified samples exhibited a temperature difference of 2.2 °C and a time lag of up to 20 min under natural cooling conditions. Notably, CB positively influenced thermal conductivity, while CNT demonstrated an unexpected minor reduction. The enhancement in thermal conductivity increased with the content of CB, reaching an optimal enhancement of 18 %, except at a CNT content of 0.5 %. Conversely, both CB and CNT consistently improved thermal diffusivity. Furthermore, the compressive strength of the modified samples was significantly enhanced by up to 24 % compared to PCM mortar without carbon modifications. The modification method proposed in this study significantly improves both the thermal and mechanical properties of PCM mortar.

Informatics-based design of polyaniline-carbon nanotube thermoelectric nanocomposite using ANN and GA

Abstract Conducting polymer and carbon nanotube (CNT) based nanocomposites have emerged as prospective thermoelectric (TE) materials due to their potential application in flexible electronics. Non-conventional charge and heat transport in these nanocomposites, presents the possibility to enhance the TE conversion efficiency, given by ZT. However, the highly non-linear and complex association of structure and composition with the overall TE properties have hindered the development of any general strategy to develop high ZT nanocomposites. Here, we implement artificial neural network (ANN) and genetic algorithm (GA) to develop data driven models followed by optimization to design high efficiency nanocomposites based on CNT dispersed in polyaniline (PANI) matrix. Our models suggest that CNT concentration plays the most crucial role in determining ZT. Non-dominated Pareto optimal solutions consisting of different combinations of design variables are obtained by multi-objective optimization. Although a range of optimal solutions span over different regions of the search space, in general we note that longer CNTs boost Seebeck coefficient (S) and electrical conductivity (σ), and smaller length lowers thermal conductivity (k), while higher diameter of CNTs increase S and lowers σ and k. The results provide a general guideline for developing CNT-PANI nanocomposites with enhanced TE figure of merit.

Three-Dimensional Printed Nanocomposites with Tunable Piezoresistive Response.

This study explores a novel approach to obtaining 3D printed strain sensors, focusing on how changing the printing conditions can produce a different piezoresistive response. Acrylonitrile butadiene styrene (ABS) filled with different weight concentrations of carbon nanotubes (CNTs) was printed in the form of dog bones via fused filament fabrication (FFF) using two different raster angles (0-90°). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) in TUNA mode (TUNA-AFM) were used to study the morphological features and the electrical properties of the 3D printed samples. Tensile tests revealed that sensitivity, measured by the gauge factor (G.F.), decreased with increasing filler content for both raster angles. Notably, the 90° orientation consistently showed higher sensitivity than the 0° orientation for the same filler concentration. Creep and fatigue tests identified permanent damage through residual electrical resistance values. Additionally, a cross-shaped sensor was designed to measure two-dimensional deformations simultaneously, which is applicable in the robotic field. This sensor can monitor small and large deformations in perpendicular directions by tracking electrical resistance variations in its arms, significantly expanding its measuring range.

Enhancement in the Electrical Properties and Electromagnetic Interference Shielding Performance of Acrylonitrile–Butadiene–Styrene/Carbon Nanotubes Foams via the Introduction of Bimodal Cell Structures

The cell structures of conductive polymer‐based composite foams significantly influence their electrical properties and electromagnetic interference (EMI) shielding effectiveness (SE), necessitating a thorough understanding of how these properties improve with evolving cell structures. In this study, supercritical CO2 foaming technique was manipulated to fabricate acrylonitrile–butadiene–styrene (ABS)/carbon nanotubes (CNTs) foams. The constant‐temperature mode was used to prepare unimodal foams (UF), while the bimodal foams (BF) were produced by varying‐temperature mode. The foaming properties, electrical conductivity, complex permittivity, and EMI SE of ABS/CNTs foams with various cell structures are methodically investigated at identical volume expansion ratio and CNTs content. The electrical conductivity of bimodal ABS/CNTs foam with CNTs content of 20% (BF‐C20) is 0.2191 S cm−1, higher than that of unimodal ABS/CNTs foam with CNTs content of 20% (UF‐C20) (0.1765 S cm−1) owing to the introduction of bimodal cell structures. Complex permittivity results manifest that at 8.2 GHz, the ε′ and ε″ of BF‐C20 are 67.7 and 74.5, respectively, which are higher than 57.9 and 52.9 of UF‐C20. Among all ABS/CNTs foams, the total EMI SE of BF‐C20 attains the highest EMI shielding value, which reaches 30.2 dB. Furthermore, the absolute shielding effectiveness of BF‐C20 is 188.5 dB (g cm−2)−1, which is 17.3% higher than that of UF‐C20.

Highly-improved microwave absorption performance of LaFeO3/Fe@CNTs nanocomposites through in-situ synthesis of Fe@CNTs

In order to enhance the microwave absorption performance, the multi-phase nanocomposites composed of magnetic medium and carbon nanotubes (CNTs) is designed and developed based on impedance matching. In this paper, LaFeO3/Fe@CNTs nanocomposites are prepared in situ using LaFeO3 as catalysts and C2H2 as carbon sources with CVD method, and then the microstructures, magnetic properties and microwave absorption performance are investigated in detail. The specific surface area of LaFeO3/Fe@CNTs nanocomposites increases greatly from 16.39 m3/g for LFC0 to 52.29 m3/g for LFC5 with the increasing CNTs content due to the enhanced heterogeneous interfaces. Ms also increases from 0.68 emu/g for LFC0 to 10.24 emu/g for LFC5 from magnetic Fe nanoparticles. LFC5 exhibits the best microwave absorption properties with the minimum reflection loss of -38.758 dB and a broad effective absorption bandwidth of 2.32 GHz at 2.5 mm. Impedance matching is balanced by permittivity from CNTs and permeability from Fe nanoparticles. Owing to the conductive CNTs with more defects, the dielectric loss and eddy current loss both increases to some extent. The synergistic loss mechanism of magnetic Fe nanoparticles and dielectric CNTs result in impedance matching and outstanding microwave attenuation.

Stretchable carbon Nanotube/Ecoflex conductive elastomer films toward multifunctional wearable electronics

Conductive elastomer films (CEFs) have found widespread applications toward flexible electronics and wearable devices. Silicones are particularly advantageous for fabricating high-performance CEFs. However, processing silicone/conductive filler composite prepolymers is challenging because of their high viscosity, especially when incorporating nanofillers like carbon nanotubes (CNTs) that can greatly increase the viscosity of silicone prepolymers. Herein, we present a simple, facile and versatile hexane-assisted air-spraying method for fabricating silicone-based CEFs from Ecoflex and CNTs. This method allows for processing CNT/Ecoflex prepolymers with CNT concentrations of 0.5 ∼ 5 wt%, resulting in stretchable CEFs with controllable structural, mechanical and electrical properties. We leveraged the distinct advantages of CNT/Ecoflex CEFs, including the excellent mechanoelectrical sensitivity, workable strain range and elasticity of the CNT1/Ecoflex group, and the high conductivity and low mechanoelectrical sensitivity of the CNT5/Ecoflex group. These properties enable their multifunctional applications as wearable and waterproof resistive strain sensors, multilayered capacitive pressure sensors, and wearable electric heaters. This work provides valuable insights into the development of high-performance and multifunctional silicone-based composite materials for advanced wearable electronics.

High-Performance Sol-Gel-Derived CNT-ZnO Nanocomposite-Based Photodetectors with Controlled Surface Wrinkles.

We investigate the effects of incorporating single-walled carbon nanotubes (CNTs) into sol-gel-derived ZnO thin films to enhance their optoelectronic properties for photodetector applications. ZnO thin films were fabricated on c-plane sapphire substrates with varying CNT concentrations ranging from 0 to 2.0 wt%. Characterization techniques, including high-resolution X-ray diffraction, photoluminescence, and atomic force microscopy, demonstrated the preferential growth of the ZnO (002) facet and improved optical properties with the increase in the CNT content. Electrical measurements revealed that the optimal CNT concentration of 1.5 wt% resulted in a significant increase in the dark current (from 0.34 mA to 1.7 mA) and peak photocurrent (502.9 µA), along with enhanced photoresponsivity. The rising and falling times of the photocurrent were notably reduced at this concentration, indicating improved charge dynamics due to the formation of a p-CNT/n-ZnO heterojunction. The findings suggest that the incorporation of CNTs not only modifies the structural and optical characteristics of ZnO thin films but also significantly enhances their electrical performance, positioning CNT-ZnO composites as promising candidates for advanced photodetector technologies in optoelectronic applications.

Influence of carbon nanotubes on the absorption performance and mechanical behavior of basalt fiber composite materials

AbstractBasalt fibers (BF) are widely used in shipbuilding due to their excellent corrosion resistance. However, basalt fibers do not possess good electromagnetic wave absorption properties, failing to meet the stealth performance requirements of ships. Therefore, this study focuses on basalt fiber composite materials, modifying the matrix by adding different amounts of carbon nanotubes (CNTs). Carbon nanotube‐basalt fiber‐epoxy resin absorptive composite materials are prepared using Vacuum Assisted Resin Transfer Molding (VARTM) technique to investigate the influence of CNT content on the materials. Samples with added CNTs can effectively absorb electromagnetic waves in the low‐frequency range, reducing surface reflectivity. In the high‐frequency range, the impedance matching value of the samples initially increases slowly. When the CNT content reaches 1.5 wt%, at a thickness of 2.5 mm and a frequency of 9.6 GHz, the minimum reflection loss of the sample is −14.40 dB, with an effective absorption bandwidth of 0.7 GHz. Also, CNTs can enhance the mechanical properties of composite materials. With increasing CNT content, both the bending strength and tensile strength of the composite materials are improved. When the CNT content reaches 1.5 wt%, the average tensile fracture strength of the material increases by 21%, and the bending strength increases by 9%.Highlights Enhanced low‐frequency electromagnetic wave absorption from CNTs and reduced polarization. Improved impedance matching and attenuation at high frequencies with CNTs. Significant enhancement in flexural and tensile strength due to CNTs and basalt fibers.

Heat Transfer in Carbon-Nanotube Dispersions: A Simulation Study of the Role of Nanotube Morphology and Connectivity

Simulation of the behavior of carbon nanotubes (CNTs) can become a very challenging task considering their complicated shape and large aspect ratio. This study aims to elucidate the role of CNT shape, length, and connectivity during heat transfer in CNT dispersions through a three-dimensional (3D) simulator. Three characteristic shapes for the CNTs are considered, namely, straight, moderately curved, and strongly curved. The results reveal that the commonly used assumption of viewing CNTs as straight cylinders leads to significant overestimation of the overall medium conductivity. The CNT length has an important effect on the nanofluid conductivity for all types of CNT shapes considered here. In addition, use of CNTs with higher conductivity than a certain value appears to have no further beneficial effect, thus relaxing the need for extremely pure or single-wall CNTs. On the contrary, the conductivity remains a strong function of the CNT concentration and may be even increased upon organization of CNTs into loose clusters. The overall approach and concept can be extended to CNT composites in a straightforward manner.

High-Quality Conductive Network Films Constructed from Carbon Nanotube/Carbon Nanofiber Composites via Electrospinning for Electrothermal Applications.

In this study, carbon nanotube (CNT)/carbon nanofiber (CNF) composite electrothermal films were prepared by electrospinning, and the effects of the CNT content and carbonization temperature on the electrothermal properties of the CNT/CNF composite films were investigated. The experimental results demonstrated that the conductivity of the CNT/CNF composite electrothermal film (0.006-6.89 S/cm) was directly affected by the CNT content and carbonization temperature. The electrothermal properties of the CNT/CNF positively correlated with the CNT content, carbonization temperature, and applied voltage. The surface temperature of CNT/CNF can be controlled within 30-260 °C, and continuously heated and cooled 100 times without any loss. The convective heat transfer with air is controllable between 0.008 and 31.75. The radiation heat transfer is controllable between 0.29 and 1.92. The prepared CNT/CNF exhibited a heat transfer efficiency of up to 94.5%, and melted a 1 cm thick ice layer within 3 min by thermal convection and radiation alone.

Cyclic loading effects on the heat-generation performance of carbon nanotube-embedded cement composites

Abstract This study investigates the heat-generation stability of carbon nanotube (CNT)/cement composites after exposing to cyclic loading conditions. The specimens were fabricated with varying CNT contents and levels of fly ash replacement. Results showed that increasing CNT content reduced electrical resistivity, while the impact on the electrical characteristics was found to be insubstantial, even though a considerable portion of fly ash was replaced. In addition, the electrical resistivity of the specimens after exposed to cyclic loading increased. Electrical heating tests revealed both negative and positive temperature coefficient effects depending on the applied voltages. Higher CNT contents improved the heat-generation capability, but the heating capability decreased after exposed to the cyclic loadings which is deduced from the damage of CNT networks during cyclic loadings. In this regard, the authors concluded that the heat-generation stability can be significantly affected by the applied loadings. Thus, the future research will be conducted to improve the heat-generation stability of the cement-based electrical heating systems as exposed to artificial deteriorations.

The improved viscoelastic properties of long‐length carbon nanotubes reinforced polyamide‐6 composites

AbstractThe semi‐crystallinity, thermoplasticity, high toughness, and light weight of polyamide‐6 (PA6) when reinforced with carbon nanotubes (CNTs) provide outstanding physical properties to the nanocomposites by combining the physical properties of both components. The processing difficulties arising due to the high toughness and abrasion resistance of PA6 and the agglomeration of in‐house synthesized long‐length CNTs can be tackled by melt‐mixing the components inside a twin‐screw extruder with a back‐flow channel. The 0.1–7 parts per hundred ratios (phr) of CNTs reinforced PA6 composites were characterized for their viscoelastic properties through oscillatory rheometry and dynamic mechanical analysis (DMA) at fixed operating conditions. The outcomes showed continuous shiftings in storage and loss modulus values with increasing reinforcements along with a viscoelastic transition at 3 phr CNTs reinforcements observed in DMA. A 19°C rise in glass transition temperature (Tg) was observed in DMA with 0.1 phr CNTs reinforcement, which showed further improvements with increasing CNTs content. The interactions among PA6 and CNTs were further confirmed by X‐ray diffraction (XRD) and Raman spectroscopy curves. These nanocomposites promise mechanical applications in the equipments of automobiles, aerospace, defense, biomedical, bio‐sensors, etc.Highlights Viscoelastic properties study for CNTs/PA6 composites Uniform intermixing of CNTs within PA6 via extrusion with back‐flow channel Detailed analysis of rheometry and DMA of the composites CNTs‐PA6 interactions estimated from rising intensity peaks in Raman spectra and X‐ray diffraction (XRD) Potential candidates for components in automobiles, aircraft, biomedicals, and sports industry

Numerical simulation of mechanical properties and damage process of carbon nanotube concrete under triaxial compression and splitting conditions

To investigate the mechanical properties and failure processes of carbon nanotube concrete, a three-dimensional meso-scale finite element model of concrete was constructed. Using ABAQUS software, numerical simulations were conducted on concrete samples with different carbon nanotube concentrations under triaxial compression and splitting conditions. The results indicate that under splitting conditions, the failure of the specimens initially occurs along the loading direction from both ends, with few cracks and slow propagation. Subsequently, the cracks rapidly expand, penetrating the entire specimen, leading to the formation of a macro-fracture surface with a crack aligned with the loading direction. This failure mode manifests as a straight crack. At the same loading rate, the tensile strength of the specimens with different carbon nanotube concentrations increases to varying degrees during splitting failure, with a maximum increase of 45.10% to 4.15 MPa. nder triaxial compression conditions, the main failure mode of the specimens exhibits shear failure characteristics. As the confining pressure gradually increases, the failure angle of the specimens enlarges. Under low confining pressure, there are fewer wing-shaped tensile cracks at the shear failure surface of the specimens. As the confining pressure increases, irregular shear failures and multiple shear planes appear in the specimens, resulting in more complex failure modes. For specimens with the same carbon nanotube concentration, the triaxial compressive strength of carbon nanotube concrete specimens increases with increasing confining pressure. The triaxial compressive strengths of the specimens under confining pressures of 5 MPa, 10 MPa, 15 MPa, and 20 MPa are 90.48 MPa, 122.72 MPa, 137.22 MPa, and 172.65 MPa, with strength increases of 35.63%, 51.66%, and 90.81%, respectively.

Periodic free vibrations of composite laminates with curvilinear fibres and CNTs

This article addresses the combined effect of using curvilinear fibres and carbon nanotubes (CNTs) reinforcements in the non-linear modes of vibration of laminated composite plates. To arrive at the material properties of the three-phase composite material, a two-step hierarchic procedure is followed. A modified version of the Halpin–Tsai model is employed to predict the Young’s modulus of the CNT enriched resin and expressions, deduced from equilibria of a unit cell where a fibre is embedded in resin, are applied to obtain the diverse elasticity moduli of the three-phase composite. Moderately large displacements are considered, with von Kármán strain–displacement relations. Although the presented model is an equivalent single layer one, it applies to thick plates, because a Third-order Shear Deformation Theory (TSDT) is followed. The set of autonomous non-linear equations of motion is reduced using static condensation and a modal basis with selected modes, chosen after a convergence analysis. The reduced set of equations of motion is solved by the shooting method. Numerical tests considering plates with diverse curvilinear fibre paths, CNT contents and thicknesses are carried out. The results obtained are thoroughly analysed.

Predicting heat transfer Performance in transient flow of CNT nanomaterials with thermal radiation past a heated spinning sphere using an artificial neural network: A machine learning approach

An efficient heat transfer phenomenon using nanofluid have greater challenges in various industries, engineering application the recent trend. Keeping this in present scenario, this study aims to optimize the heat transmission rate in the magnetized flow of nanomaterials through a rotating, spinning sphere. The heat transfer phenomena in the time-dependent fluid are enhanced by the incorporation of nonlinear radiation and a variable heat source. Additionally, the free convective flow is influenced by the effects of thermal buoyancy and a transverse magnetic field. The proposed model along with several factors is standardized through adequate transformation rules. Further, shooting-based Runge-Kutta technique is adopted with the help of built-in MATLAB function bvp4c for the solution of the transformed system. The prime focus of the proposed work is the optimizing heat transfer rate combined with regression analysis using artificial neural network and then it uses Levenberg Marquardt algorithm with well-posed training, testing, and validation data. The error analysis also presented briefly and the variation of characterizing parameters is depicted via graphs. Further, the important outcomes are; the particle concentration of carbon nanotubes contributes to decelerating the velocity profiles, leading to an increase in boundary layer thickness. In contrast, increasing magnetization has the opposite effect. Both nonlinear radiative heat and an additional heat source enhance the heat transfer phenomenon.

In situ foam 3D printed microcellular multifunctional nanocomposites of thermoplastic polyurethane and carbon nanotube

Electrically conductive and mechanically robust thermoplastic polyurethane (TPU)/carbon nanotube (CNT) foams were achieved using a novel in situ foam 3D printing (F-3DP) process. Thermally expandable microspheres (TEMs), as blowing agent, were incorporated into the TPU/CNT filaments and fed to the F-3DP process. Foams with uniform morphologies and repeatable properties were achieved in a wide density range by solely regulating the nozzle temperature and its correlated flow rate. Overall, the degree of foaming increased substantially with an increase in the temperature, providing a density range of 0.96 to 0.17 g/cm3. It was interestingly found that a small amount of CNT (1 wt%) increased the expansion ratio. A further increase of CNT (to 3 and 5 wt%), however, caused a reduction in the expansion ratio. These opposing trends were attributed to the competing effects of CNT on the melt's thermal conductivity and viscosity. Both CNT content and nozzle temperature exhibited significant impacts on the tensile properties and electrical conductivity. This resulted in foams with diverse Young's modulus and strain at break in the range of 3.9–29.5 MPa and 260 to 52 %, respectively. More importantly, the electrical conductivity increased up to several orders of magnitude, as the foam expansion was increased due to temperature rise. This interesting finding was thoroughly discussed in terms of the enhanced inter-bead adhesion, vanishing inter-bead gaps, and realignment of CNTs around the growing TEMs. The results demonstrate a great potential of F-3DP to produce functional foams with controllable density and performance in a wide range.

Optimization and tribological behavior of carbon nano tubes blended with POE oil

Over the past two decades, nano additive lubricants have become essential in manufacturing as lubricating agents. Our study examines the impact of three process parameters—carbon nanotube (CNT) (volume concentration,%), sliding velocity (m/s), and applied load (N)—on the tribological performance of polyolester oil blended with carbon nanotubes. By employing the robust Taguchi L9 orthogonal array as the design of experiment, the current study made an attempt to identify the best combination of these three factors parameters to achieve the least coefficient of friction (COF) while the study also conducted ANOVA and multivariate linear regression to determine the significant factor that determines the least COF. For this study, POE oil and varying concentrations of CNTs (such as 0.05, 0.075 and 0.1 volume concentration%) were used. For this study, the characterization of the CNTs was performed using TEM, SEM and XRD methods while its stability was validated through Zeta potential value i.e., 0.075 volume concentration% CNT concentration achieved 35 mV zeta potential value. The Taguchi L9 orthogonal array outcomes found the least COF i.e., 0.0359 was achieved from 0.075 volume concentration % of CNT with a sliding speed of 3.6 m s−1 at 50 N load. The ANOVA outcomes confirmed the major contribution (91%) of the CNT concentration towards influencing the COF outcomes. The contour plots confirmed that optimal COF can be achieved when using 0.075 volume concentration% CNT with load ranged from 75 N to 125 N and sliding velocities between 1.2 m s−1 and 3.0 m s−1. The outcomes establish that when POE oil is supplemented with CNTs, it can achieve superior performance as the nanolubricant mitigates the coefficient of friction (COF), eventually enhancing the tribological performance. Future researchers can focus on employing Taguch-grey relational analysis, artificial intelligence and machine learning models to find the optimal process parameters for other lubricants and nanoadditives.

Preparation of carbon nanotube composite solder and analysis of the thermal properties

Abstract The solder layer constitutes a crucial component of IGBT power modules. It endures significant thermal stress during operation, and the magnitude of this stress correlates with the coefficient of thermal expansion. To prevent fatigue damage to the solder layer during operation, it is necessary to reduce the solder’s coefficient of thermal expansion, thereby alleviating the impact of thermal stress. In this paper, the method of adding carbon nanotube powder to solder is proposed to solve this problem. Firstly, the relationship between thermal stress and the coefficient of thermal expansion is analyzed, and then the mechanical ball milling method is employed to prepare composite solder with a 0.05% carbon nanotube content. Scanning electron microscopy observation of the prepared composite solder reveals homogeneous mixing and uniform distribution of carbon nanotubes on the solder particle surfaces. Furthermore, thermal expansion coefficient tests were conducted on the sintered carbon nanotube composite solder, revealing a 16.2% reduction in the coefficient due to the incorporation of carbon nanotubes.