Graphene Particles Research Articles

Stacking of Monolayer Graphene Particles at a Water–Vapor Interface

Two-dimensional (2D) materials such as graphene prefer to interact in a face-to-face manner when colloidally suspended but are forced to interact in an edge-to-edge manner when trapped at a fluid–f...

Optimization of EDM Process Parameters on Machining Characteristics of SiC and Graphene Reinforced Al 6061-T6nano-Composites

Aluminum composites play an important role in various applications due to their low weight to strength ratio, high corrosive resistance, etc. As reinforcement materials, Graphene and SiCnano particles were used. Since, they havea high melting point, young modules, strong electrical and thermal properties etc. Electrical Discharge Machining (EDM) is one of the non-conventional machining techniques widely used for the machining of hard materials such as composites. The aim of current work is to evaluate the influence of EDM process parameters such as peak current, pulse on-time, voltage and flushing pressure on machining of Aluminium 6061 reinforced with 0.5 wt% SiC and 0.5 wt% Graphene nanoparticles. Al-based Metal Matrix Composite was casted by using liquid processing technique i.e. Stir Casting. Taguchi’s Design of Experiments was used to evaluate the effect of process parameters on machining characteristics i.e. Material Removal Rate (MRR) and Tool Wear Rate (TWR) of developed composite. From the results it was observed that peak current is the most influencing factor on MRR and TWR followed by other parameters.

Study of Microwave-Assisted MoS2 and Graphene Composite Counter Electrode for Dye-Sensitized Solar Cells

Graphene-MoS2 composites were synthesized via one-step microwave-assisted chemical bath deposition and used as counter electrodes for dye-sensitized solar cells, instead of traditional Pt film which has high cost and poor stability. The effects of graphene additive amount on the performance of cells were studied. The results reveal that sheet porous structure graphene and MoS2 particles has been incorporated tightly, which is the benefit of electrical conductivity and catalysis ability. A maximum efficiency of 6.3% has been achieved under 100 mW cm−2 illumination when the Mo:C is 1:1.

Effect of iron oxide and graphene particles on joint strength and dismounting characteristics of a thermoplastic adhesive

A thermoplastic adhesive modified with iron oxide particles (IO) and graphene nanoplatelets (GNPs) has been used to ease the dismounting process of plastic component assemblies by using microwave or induction heating systems. GNPs have been added to an adhesive already modified with iron oxide particles (10% in weight) to melt the adhesive and separate adhesive joints in a more rapid and efficient way compared to the adhesive preliminarily adopted by the same authors. The IO-based thermoplastic adhesive was modified with three different GNP weight concentrations, namely 0.1%, 0.5%, and 1.0%. The mechanical properties have been evaluated through single lap joint (SLJ) tests. These tests showed that the maximum sustained load and the elastic moduli of the joints increase together with the increase of GNP percentages. Microwave or induction heating tests conducted on all the adhesive compositions showed that it is possible to melt the adhesive rapidly and thus separate the plastic joints in a very rapid way, 14 s, and 10 s respectively for the cases that embed 1% of GNPs. Scanning electron microscope (SEM) showed that the extruder can mix uniformly these particles without the formation of agglomerates.

Microstructural and Mechanical Properties of AZ31B/Graphene Nanocomposite Produced by Stir Casting

In the current scenario, the development of high strength and low weight material is the demand of the aerospace defence organizations. Magnesium alloy based composite has low density, good mechanical and physical properties. In this study, magnesium alloy AZ31B is used as reinforcement material and graphene nanoparticle is used as reinforcement material. Stir casting technique is used for the development of composite material. Three weight percentages i.e. 0.4%, 0.8% and 1.2% are used for the casting. The microstructural analysis is performed to validate the presence of graphene particles in the developed composite. Further mechanical properties such as tensile strength, hardness and toughness are evaluated. Experimental results confirm that GNPs particles are uniformly distributed into the matrix material. It was observed that due to the reinforcement of GNPs particles tensile strength of the material is improved by 31.17%, hardness is improved about 46.9%. However, the peak value of toughness is observed 12.6 Jule/cm2 in the matrix material, it decreases by increasing the wt% of reinforcement particle and lowest value of toughness of 6.82 Jule/cm2 is observed in AZ31B/1.2%GNP composite.

3D printed stretchable smart fibers and textiles for self-powered e-skin

E-textiles are of great significance for next-generation wearable electronics. However, the current smart textiles generally have shortcomings such as intricate preparation processes and redundant structure. Here, we have developed a 3D printing method to prepare stretchable elastic fibers with a coaxial core-sheath structure, which consists of conductive core and insulative sheath. The addition of graphene and PTFE particles successfully manipulates the rheological behavior of the PDMS prepolymer and makes it suitable for 3D printing of core-sheath coaxial stretchable fibers. Furthermore, the large-scale and customized manufacturing of stretchable smart textiles has been achieved. Based on triboelectric effect, the core-sheath elastic fiber can perform the function of wearble tactile sensing as e-skin and the smart textile demonstrates the ability of matrix tactile sensing through the interlaced structure of warp and weft. Moreover, the smart textile has many advantages such as washability, breathability, super stretchability and robustness, making it promising for wearable electronics.

Modeling of Active Gap Capacitance Electrical Discharge Machining

Abstract Active gap capacitance electrical discharge machining (AGC-EDM) is a high-speed EDM method for machining polycrystalline diamond tools utilizing the active capacitive effect and powder mixing effect formed by the kerosene dielectric added with graphene particles. The capacitive effect increases the discharge energy and explosive force, which in turn influences the material removal efficiency; the powder-mixed effect changes the states of dielectric and forms a non-fixed gap discharge process. Take into account these two aspects, a new discharge mechanism of AGC-EDM is proposed to describe the discharge process. Capacitance characteristics and chain stacking process of graphene-kerosene dielectrics are verified by experimental results. The material removal rate, relative electrode wear, and surface roughness are discussed with the pulse duration, peak current, and graphene concentration to study the theories of the new EDM process.

Application of graphene in electrical resistance electromagnetic shielding fabric

Graphene is a kind of material formed by Sp2 hybridization of carbon atoms, which has been widely used in various scientific research fields in recent years. In this paper, the mechanism of electromagnetic shielding on fabrics and the recent development of resistance type electromagnetic shielding materials are introduced. The effects of graphene and metal particle composites, graphene and high conductivity polymer composites, carbon nanotubes and high conductivity polymer composites on fabrics are briefly described. The optimization of electromagnetic shielding effectiveness and the future development of shielding materials is prospected.

A graphene-modified Co-BDC metal-organic frameworks (Co-MOF) for electrochemical non-enzymatic glucose sensing

In this work, a metal-organic framework (MOF) based on cobalt was decorated with graphene and used as a sensing material for glucose determination with electrochemical principles. The selection of Co-MOF material is based on its porous nature, large surface area, and excellent electrochemical properties. The combination of Co-MOF with graphene (high conductivity) effectively increased the electrochemical sensor current. The fabricated composite owned the good crystallinity with graphene particles attached to the Co-MOF surface. The biosensing performance was evaluated by cyclic voltammetry (CV) with 0.1 M NaOH solution as the bolstering electrolyte. The electrochemical measurement indicated that the prepared materials possessed a well-moved transfer electron between the electrode surface and electrolyte solution. The Co-BDC-3Gr sample obtained the best electrochemical performance with the lowest limit of detection (LOD) of 5.39 μM and the highest sensitivity of 100.49 μA mM-1 cm-2. The selectivity test of the modified Co-MOF was done by comparing the response with other compounds such as dopamine, uric acid, and NaCl. The acquired biosensor had excellent stability, with 93% of the initial response after 30 days of storage.

Improved Fracture Toughness and Crack Arrest Ability of Graphene–Alumina Nanocomposite

In this work, high fracture toughness graphene–alumina composite was developed through a novel chemical method using boehmite and graphene, which is followed by extrusion and consolidation. The mixed precursors were consolidated by sintering at 1550 °C in a nitrogen atmosphere. The plate-like structures of boehmite form α-alumina; meanwhile, graphene particles at the grain boundaries hinder the growth of alumina grains. The graphene reinforcement was bonded to α-alumina matrix by van der Waals forces. The XRD pattern reveals the presence of graphene with a plane (002) along with α-alumina. Properties such as fracture toughness (5.6 ± 0.01 MPa m0.5), Vickers hardness (1872 ± 25 kgf/mm2) and true density (3.8 g/cm3) were achieved in 0.5 wt.% graphene–alumina composite when compared to α-alumina with fracture toughness (5.3 ± 0.1 MPa m0.5), Vickers hardness (1984 ± 28 kgf/mm2) and true density (3.91 g/cm3). The bridging and deviation of cracks in 0.5 wt.% graphene–alumina composite are attributed to the anchoring and dissipation of energy during crack growth, which enhances the fracture toughness, whereas α-alumina exhibits failure caused by linear crack propagation. Meanwhile, the slight decrease in Vickers hardness and true density of 0.5 wt.% graphene–alumina composite is due to the tribological and low-density properties of graphene. The obtained properties of composite could be suitable in high-temperature, wear-resistant applications such as crucibles, bearings, etc.

Synthesis and characterization of ZrO2 and graphene particle reinforced Al6061 metal matrix composites

The present work involves preparation of ZrO2 and graphene particle reinforced Al 6061 metal matrix composite (Al6061-1 wt% ZrO2-1 wt% graphene). The composite is processed using stir casting method. Microstructural characterization is carried out using Image analyzer and confirms the presence of zirconium and graphene particles. A uniform distribution of reinforcement is observed throughout the matrix. The morphology of incorporated particles is discussed and particle sizes are evaluated using metallurgical microscope. Tensile tests are carried out to study the effect of reinforcement in the matrix and the results are reported. It is observed that the load at the yield point is greater than 9.9 KN. During fracture, the bond between the reinforcement and the matrix detaches and subsequently leads to the formation of dimples.

Mathematical regularities of changes in the characteristics of the friction process of a porous composite material based on copper containing oil with graphene particles

The paper presents the results of a study of the sliding friction processes of a porous copper-based material impregnated with lubricating oil with dispersed particles of fluorinated graphene. Mathematical regularities of changes in the characteristics of the friction interaction are established. It is shown that the regularities of changes in the average friction force have a sigmoid-step character. Experimental results have been obtained showing that with an increase in the concentration of aggregates from flakes of fluorinated graphene in the lubricating oil, the average friction force and coefficient of friction decrease, while a good anti-friction effect is observed. It is shown that the average work of the friction force, and consequently the energy losses due to friction, when adding 0.01% of aggregates from fluorinated graphene flakes to the lubricating oil decreases by 3721 j, and when adding 0.1% — by 4098 j. It was found that the average coefficient of friction when adding 0.01% of fluorinated graphene flake aggregates to the lubricating oil decreases by 27%, and when adding 0.1% — by 30%.

Numerical and experimental analysis of thermal conductivity of PC-ABS nanocomposite reinforced with graphene developed by fused deposition modeling

Present investigation focuses on numerical and experimental studies on thermal conductivity of polymer nanocomposites reinforced with graphene particles. Fused Deposition Modelling (FDM) a process of Additive Manufacturing (AM) is used to develop nanocomposite specimens for analysis of thermal conductivity. Polycarbonate (PC) – Acrylonitrile Butadiene Styrene (ABS) was taken as matrix material in definite proportion and Graphene was added in different weight proportions. The mixture was developed into filament of 1.75 mm through the process of compounding and extrusion. The test samples were developed through FDM. Experimental results were compared with well known mathematical models for thermal conductivity test from the literature. The variation of thermal conductivity behaviour with varied percent of graphene is elaborately discussed in this study.

Preparation of New Anthracene Based Copolymer System and Graphene Composites, Investigation of Thermal and Electrical Properties

Bu çalışma, antrasen içeren kalkon yan zincirli yeni kopolimer sisteminin termal ve elektriksel özelliklerini incelemeyi amaçlamıştır. Monomer ve kopolimerlerin yapıları FT-IR, 1H-NMR ve 13C-NMR teknikleri kullanılarak karakterize edildi. Kopolimerlerin termal davranışları DSC ve TGA kullanılarak analiz edildi. Kopolimerdeki antrasen birimlerinin artmasıyla camsı geçiş sıcaklığının 123 °C'den 142 °C'ye yükseldiği gözlemlendi. Kopolimer matriksine % 4 grafen partikülleri ilave edilerek yarı-iletken kompozitler hazırlandı. Kopolimerlerin ve grafen kompozitlerinin dielektrik ölçümleri 100 Hz-20 kHz frekans aralığında empedans analizör tekniği kullanılarak incelendi. P(MMA-ko-AAPAc 0.43)’ın dielektrik sabiti grafenin ilavesiyle 5.21'den 273.28'e yükseldi. Kompozitlerin aktivasyon enerjisi değerleri, sıcaklığın bir fonksiyonu olarak DC iletkenliği ölçülerek elde edildi. Aaktivasyon enerjisi değerleri P (MMA-ko-AAPAc 0.16), P (MMA-ko-AAPAc 0.31) ve P (MMA-ko-AAPAc 0.43) için sırasıyla 0.320, 0.077 ve 0.040 eV olarak belirlendi.

The influence of GNP and nano-silica additives on fatigue life and crack initiation phase of Al-GFRP bonded lap joints subjected to four-point bending

As bonded components of many industrial structures are inevitably under bending fatigue loads, it is essential to improve their mechanical behavior under these loads. This paper aims to investigate the influence of adding graphene and silica nano-particles to Araldite 2015 adhesive on the fatigue behavior of aluminum-to-composite bonded single lap joints (SLJs) by a novel fixture under four-point bending. Four adhesive groups were prepared: I) neat, II) nano silica-reinforced, III) nano graphene-reinforced (groups II and III include 0.5 wt%, 1.0 wt%, and 1.5 wt% contents), and IV) a mixture of these particles (0.5 wt% of each particle). Besides, all nano-reinforced groups were prepared with similar processing steps including magnetic stirring (30 min duration, speed of 180 rpm) followed by ultrasonic mixing (1 h duration) and vacuum oven drying. Tensile tests indicated that the tensile strength of the graphene-reinforced bulk specimens was greater than that of silica-reinforced ones for 0.5 wt% and 1 wt% of filler contents. Also, the average static failure load (ASFL) of the graphene-reinforced SLJs under four-point load was greater than that of silica-reinforced joints for 0.5 wt% and 1 wt%, and it was lower than that of the silica-reinforced specimens for 1.5 wt% of particle contents due to the presence of more agglomeration of nano graphene particles in the adhesive. Then, for maximum fatigue loads of 40%–70% of ASFL, and load ratios of R = 0.5, 0, and −1, load vs. life cycle curves were examined for all SLJ groups. The ASFL and fatigue life of group IV SLJs (mixture of 0.5 wt% of each particle) were improved compared to the joints reinforced by separate usage of each particle with 1 wt% content. Using backface strain measurements, the influence of adding nano-particles on retarding the crack initiation phase was discussed under different load conditions. Finally, optical microscope observations indicated that adding nano-particles changes the failure mode from adhesive to cohesive. The major reinforcing mechanisms encountered in this research were interpreted by scanning electron microscopy.

Experimental Study on the Flow and Heat Transfer of Graphene-Based Lubricants in a Horizontal Tube

To improve the heat transfer characteristics of lubricant, graphene-based lubricants were prepared by adding graphene particles, due to its advantages of excellent thermal conductivity and two-dimensional sheet structure. In the present study, its physical properties were measured. A flow heat transfer experiment platform was built to study the flow and heat transfer characteristics of the graphene lubricating oil in a horizontal circular tube. The results show that the graphene lubricant prepared using a two-step approach had good stability, and the dispersibility was good without the agglomeration phenomenon, according to measurements undertaken using an electron microscope and centrifuge. The thermal conductivity and viscosity of graphene lubricant increased with the increase of the graphene concentration, and the thermal conductivity of graphene lubricant with the same concentration decreased with the increase of temperature. When the concentration was equal, the convective heat transfer Nusselt number (Nu) of graphene lubricant increased with the increase of Reynolds number (Re). When Re was equal, the convective heat transfer Nu increased with the increase of graphene particle concentration, and the maximum Nu increased by 40%.

Role of Graphene in Constructing Multilayer Plasmonic SERS Substrate with Graphene/AgNPs as Chemical Mechanism-Electromagnetic Mechanism Unit.

Graphene–metal substrates have received widespread attention due to their superior surface-enhanced Raman scattering (SERS) performance. The strong coupling between graphene and metal particles can greatly improve the SERS performance and thus broaden the application fields. The way in which to make full use of the synergistic effect of the hybrid is still a key issue to improve SERS activity and stability. Here, we used graphene as a chemical mechanism (CM) layer and Ag nanoparticles (AgNPs) as an electromagnetic mechanism (EM) layer, forming a CM–EM unit and constructing a multi-layer hybrid structure as a SERS substrate. The improved SERS performance of the multilayer nanostructure was investigated experimentally and in theory. We demonstrated that the Raman enhancement effect increased as the number of CM–EM units increased, remaining nearly unchanged when the CM–EM unit was more than four. The limit of detection was down to 10−14 M for rhodamine 6G (R6G) and 10−12 M for crystal violet (CV), which confirmed the ultrahigh sensitivity of the multilayer SERS substrate. Furthermore, we investigated the reproducibility and thermal stability of the proposed multilayer SERS substrate. On the basis of these promising results, the development of new materials and novel methods for high performance sensing and biosensing applications will be promoted.

(Invited) New Structural Design and Synthesis of Sulfur-Carbon Composite Materials for Lithium-Sulfur Batteries

The development of electric vehicles and smart grids necessitates the search for next-generation secondary batteries possessing increased energy densities, with the lithium-sulfur (Li-S) battery being one of the most promising candidates satisfying these demands. Specifically, Li-S batteries are promising energy storage and conversion systems owing to their high theoretical specific energy capacity (1675 mAh g-1) and energy density (2567 kWh kg-1) [1]. However, the practical use of Li-S batteries is hindered by their low specific capacity, low coulombic efficiency, poor rate capability, and poor cycling stability caused by the low conductivity of sulfur (5 x 10-30 S cm-1), dissolution of polysulfides (Li2Sx, 2≤ x ≤ 8) in the electrolyte and their redox shuttling/parasitic reactions and high volume expansion during discharge [2]. To overcome these drawbacks, many studies have focused on developing the design and materials of nanostructured host, electrolyte, interlayers, separators, additives, etc [3]. Interconnected three-dimensional frameworks comprising multi-walled carbon nanotubes, graphene, or carbon particles offer a combination of constituent advantages and can thus be used to achieve superior energy conversion and storage properties.Herein, we designed and prepared various approaches for interconnected highly conductive carbon materials which enable to make sulfur composite materials for Li-S batteries. The resultant sulfur-carbon composite paper cathode exhibited high reversible specific capacity of 1386 mAhg-1, good rate capability up to 5C, and excellent cycling performance (a capacity retention 68% after 400 cycles), all of which are significantly improved from those of bare sulfur cathode or sulfur-GO composite only [5]. Rational design of cathode composition, structure, and a simple fabrication process can give insight into the development of various advanced cathode materials for high performance Li-S batteries.

Effect of Graphene Additive on Flexural and Interlaminar Shear Strength Properties of Carbon Fiber-Reinforced Polymer Composite

Composite materials are widely used in various manufacturing fields from aeronautic and aerospace industries to the automotive industry. This is due to their outstanding mechanical properties with respect to their light weight. However, some studies showed that the major flaws of these materials are located at the fiber/matrix interface. Therefore, enhancing matrix adhesion properties could significantly improve the overall material characteristics. This study aims to analyze the effect of graphene particles on the adhesion properties of carbon fiber-reinforced polymer (CFRP) through interlaminar shear strength (ILSS) and flexural testing. Seven modified epoxy resins were prepared with different graphene contents. The CFRP laminates were next manufactured using a method that guarantees a repeatable and consistent fiber volume fraction with a low porosity level. Short beam shear and flexural tests were performed to compare the effect of graphene on the mechanical properties of the different laminates. It was found that 0.25 wt.% of graphene filler enhanced the flexural strength by 5%, whilst the higher concentrations (2 and 3 wt.%) decreased the flexural strength by about 7%. Regarding the ILSS, samples with low concentrations (0.25 and 0.5 wt.%) demonstrated a decent increase. Meanwhile, 3 wt.% slightly decreases the ILSS.

Study on the Thermal Conductivity of Mannitol Enhanced by Graphene Nanoparticles for Thermoelectric Power Generation

The existing thermoelectric materials are greatly affected by the temperature environment, which can provide better power output in a stable temperature environment by using composite phase change material with enhanced heat conduction. The graphene is dispersed in the liquid mannitol to make the nanomixed material. Test results show that the thermal conductivity of mannitol increased from 0.7 Wm-1 K-1 to 2.07 Wm-1 K-1, 179.73% times as much. The effective thermal conductivity of mannitol can be increased to 8.4236 Wm-1 K-1 by using a graphite foam with a porosity of 0.9. After adding 1 wt.% and 5 wt.% graphene particles, the effective thermal conductivity increased to 8.73 Wm-1 K-1 and 9.63 Wm-1 K-1, respectively. The simulation results in a large heat source environment show that mannitol with improved thermal conductivity can ensure the stable operation of the thermoelectric material in the optimal temperature environment for 120 s, and the open-circuit voltage is maintained at about 6.5 V in that time.