Addition Of Graphene Research Articles

Experimental investigation of usage of POE lubricants with Al2O3, graphene or CNT nanoparticles in a refrigeration compressor.

In this study, the use of nanolubricants containing Al2O3, graphene, and carbon nanotubes (CNTs) at different mass fractions in a refrigeration compressor was experimentally investigated. The required electrical power of the compressor was measured to determine the effect of the use of nanolubricants. Nanoparticles used in the preparation of nanolubricants were gradually added to the lubricant to determine the optimum nanoparticle mass fraction for each nanoparticle type. Thus, it was found that the compressor operated safely and efficiently with nanolubricants. Furthermore, the optimum mass fractions were determined to be 0.750% for Al2O3, 0.250% for graphene, and 0.250% for CNTs for operating conditions of this study. As a result, the required electrical power of the compressor decreased by 6.26, 6.82, and 5.55% with the addition of Al2O3, graphene, and CNT nanoparticles at optimum mass fractions of 0.750, 0.250, and 0.250% to the lubricant, respectively, compared to the compressor using pure oil. Moreover, density and dynamic viscosity of the nanolubricant samples used in the experiments were also measured, and their kinematic viscosity, which is an important parameter for lubricants, was calculated. It was determined that the kinematic viscosity continuously increased with increasing nanoparticle fraction. In conclusion, nanolubricants containing nanoparticles above the optimum mass fraction increase the required electrical power of the compressor. It is concluded that nanoparticle fractions should not be used above the optimum value in nanolubricant applications.

Low infrared emissivity epoxy resin/Ag composite coating with outstanding mechanical properties and saltwater resistance

In this study, a low infrared emissivity coating with good mechanical properties and salt water resistance was prepared by the glass rod coating method, using epoxy resin, flake Ag powder, and graphene as a functional pigment, binder, and interface modifier, respectively. The study systematically investigated the impact of Ag powder particle size, as well as the addition of silver powder and graphene, on the coating properties. The larger particle size of the Ag powder led to a significant decrease in emissivity and enhancement of the mechanical properties of the coating. The coating had optimal emissivity and mechanical properties at an Ag particle size of 10 μm. The emissivity and glossiness of the coating can be significantly reduced with the increase in added Ag powder, and the mechanical properties will be significantly improved. The increase in added graphene significantly reduced the glossiness and improved the flexibility of the coating. With a graphene content of 8 wt%, the coating has the best emissivity, glossiness, and mechanical properties at the same time. The epoxy resin/Ag composite coating, modified by graphene, showed good salt water resistance. After being corroded by salt water for 21 days, the emissivity, glossiness, adhesion strength, flexibility, and impact strength of the coating reached 0.535, 14.7, grade 1, 2 mm, and 50 kg · cm, respectively.

Influence of Graphene Additives on Dynamic Strength and Failure of Alumina under Shock Loading

Influence of Graphene Additives on Dynamic Strength and Failure of Alumina under Shock Loading

A Prediction of Graphene Nanoplatelets Addition Effects on Diesel Engine Emissions

There are numerous methods for reducing diesel exhaust emissions. Engine modifications, combustion optimization, and exhaust gas treatment are all popular methods. Another proven method uses fuel additives, such as zinc oxide, copper oxide, and magnesium oxide. Those additives are proven to reduce measured emissions such as carbon monoxide and nitrogen oxide successfully; however, there are still concerns about the toxicity of the emissions, which could harm human health. As a result, carbon nanoparticles have been introduced as a fuel additive due to their low risk to human health. Because of advancements in graphene research, a few researchers began investigating the implications of using graphene nanoplatelets as a fuel additive. The study’s findings appeared to be encouraging. However, no additional research has been identified to forecast the impact on engine emissions other than analyzing the effects of graphene additives on engine emissions. The goal of this study is to forecast the effects of graphene nanoplatelets on diesel engine emissions. The emission parameters of the trial were carbon monoxide, carbon dioxide and nitrogen oxide. The factors considered in the experiment are speed, load, and blend concentration. Response surface methodology and contour plots were generated using Minitab software. The results show that the prediction model’s accuracy is within 10% of the experimental data.

Effect of graphene on the surface nanomechanical behavior and subsurface layer of GaN damage during nanogrinding using molecular dynamics simulation

Molecular dynamics simulations were used to investigate the surface nanomechanical behavior and subsurface layer damage of gallium nitride (GaN)/graphene composites when subjected to nanogrinding with diamond abrasive. The effects of graphene on GaN were analyzed based on parameters such as atomic displacement, forces, crystal structure, subsurface damage, atomic stress, and temperature. The simulation results indicate that graphene has a noteworthy impact on the surface morphology, such as the pile-up atoms on the workpiece surface and the elastic recovery on the machined surface. In addition, the addition of graphene can reduce the atomic temperature, stress, and normal and tangential forces. In terms of subsurface damage formation, graphene can suppress lattice damage and amorphization of GaN during nanogrinding. The addition of graphene can significantly reduce the dislocation length and the phase transition from wurtzite to a five-fold coordination hexagonal structure. Overall, the addition of graphene can improve the deformation mechanism on the GaN surfaces. This study provides technical references for the design of GaN with improved friction and wear resistance.

Passivating Grain Boundaries via Graphene Additive for Efficient Kesterite Solar Cells.

Grain boundaries (GBs)-triggered severe non-radiative recombination is recently recognized as the main culprits for carrier loss in polycrystalline kesterite photovoltaic devices. Accordingly, further optimization of kesterite-based thin film solar cells critically depends on passivating the grain interfaces of polycrystalline Cu2 ZnSn(S,Se)4 (CZTSSe) thin films. Herein, 2D material of graphene is first chosen as a passivator to improve the detrimental GBs. By adding graphene dispersion to the CZTSSe precursor solution, single-layer graphene is successfully introduced into the GBs of CZTSSe absorber. Due to the high carrier mobility and electrical conductivity of graphene, GBs in the CZTSSe films are transforming into electrically benign and do not act as high recombination sites for carrier. Consequently, benefitting from the significant passivation effect of GBs, the use of 0.05wt% graphene additives increases the efficiency of CZTSSe solar cells from 10.40% to 12.90%, one of the highest for this type of cells. These results demonstrate a new route to further increase kesterite-based solar cell efficiency by additive engineering.

Conversion of CO2‐Derived Amorphous Carbon into Flash Graphene Additives

AbstractCO2 emissions have become a significant environmental problem over the last few decades, often stemming from combustion of fossil fuels. Production and disposal of waste plastic also contribute greatly to greenhouse gas emissions, due to combustion of fossil fuels during manufacture and incineration or pyrolysis of the waste materials. Hence, researchers have begun developing technologies geared toward the capture, sequestration, and utilization of CO2. Several methods are shown to be useful for conversion of gaseous CO2 into solid carbon feedstocks, such as molten carbonate electrolysis. At the same time, flash Joule heating can rapidly and inexpensively convert carbon‐rich feedstocks into flash graphene (FG). Here, amorphous carbon derived from molten carbonate electrolysis of carbon dioxide is converted into FG, sometimes in combination with waste plastic, and demonstrated for use as a reinforcing additive in composite applications. FG can be used in epoxy and vinyl ester resins with a maximum increase in Young's modulus and hardness of 73% and 73%, respectively. Life cycle assessment also shows that adding 5 wt% 25:75 amorphous carbon‐derived FG to the epoxy results in 7.7%, 5%, and 2.7% decreases in CO2 emissions, water consumption, and energy consumption, respectively.

Compatibilizing effect of grafted recycled graphene on the viscoelasticity and mechanical performance of polypropylene composites

The interface problem encountered with the graphene addition in polyolefin composites is an important issue and it is necessary to use various compatibilizers to overcome this problem. Maleic anhydride grafted Polypropylene (MAPP), which is an extensively used compatibilizer in PP composites tends to eliminate these interfacial problems by interacting physically through PP chains and allows easier stress transmission from matrix to reinforcer. However, there is a lack of understanding about how this compatibilizer works with graphene-based PP composite systems since MAPP is mostly used to harmonize hydrophilic surfaces of fillers with non-polar PP. With this study, instead of direct usage of MAPP and GNP separately, waste tyre driven graphene nanoplatelets (GNP) was grafted by MAPP and the resulted material (MAPP-g-GNP) was compounded with PP by applying high shear rates at a melt phase. Effect of MAPP-g-GNP on the processability, viscoelastic response, and mechanical performance of PP composites were investigated, and high degree of interfacial enhancement was achieved by chemically combined MAPP with amphiphilic type of GNP in PP matrix. The use of MAPP-g-GNP at a loading ratio of 0.1 wt% resulted in 38% increase in flexural modulus and 26% in flexural strength and tensile modulus compared to neat PP. The two additives used in the PP composite (2 wt% MAPP and 0.1 wt % GNP) were reduced to a single additive (PP/MAPP-g-GNP) with a 95% weight reduction in the additive content of PP. Rheological studies support that MAPP is not as successful as MAPP-g-GNP in strengthening the interface when used alone with GNP due to the lower complex viscosity and the higher crossover frequency. This study contributes to the production of high-performance PP materials with a very low amount of combined GNP and compatibilizer by integrating the circularity approach in compound development by using GNP obtained from recycled and upcycled waste tyres.

Microstructure and tribological behavior of Al–12Si – Nano graphene composite fabricated by laser metal deposition process

To improve the wear resistance of the Al-based alloys and extend its application spectrum, graphene nano-platelets (GNPs) reinforced Al–12Si matrix composites were fabricated by laser melting deposition (LMD) technology. The microstructure, wear morphologies and surface roughness were characterized by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) setups and 3D confocal microscopy. The microhardness and high-speed reciprocating frictional properties both Al–12Si and GNPs/Al–12Si composites were evaluated. The addition of graphene significantly refines the microstructure and improves the wear resistance of the matrix. The formation of a relatively stable mechanically mixed layer (MML) reduces the contact area between the friction pair material and the wear surface, the wear rate and roughness of the Al–12Si – 0.5 wt% GNP reinforced composites decrease with the increase of sliding speed, and the wear mechanism changes from adhesive wear accompanied by abrasive wear to fatigue wear. Meanwhile, as the load increases, the wear rate and roughness increase. The wear mechanism of the composite changes from abrasive wear to a mixed mode (combination of both adhesive and abrasive). This research not only offers valuable information about the Al–Si-based composites but provides theoretical light on their industrial applications.

STUDY OF THE PROPERTIES AND INTERFACIAL ENERGY OF GRAPHENE-MODIFIED ASPHALT BASED ON MOLECULAR DYNAMICS

In this paper, a molecular dynamics simulation was used to examine the physical, mechanical, and interfacial adhesion characteristics of graphene-modified asphalt. The results show that the physical properties, mechanical properties and interfacial adhesion work of modified graphene are higher than those of the base asphalt model, indicating that the addition of graphene can improve the mechanical properties and interfacial interaction of asphalt. Asphalt and aggregate mainly interact through physical adsorption, and the Van der Waals force plays an important role in the adhesion behavior of the asphalt-calcite interface. There is an optimal value for the content of graphene, such that the content of graphene added to the asphalt should not be too high. Considering the graphene price factor and modification effect, the graphene content studied is optimal at 1.79 w/%.

Graphene induced carbon-based fibre composite as microwave absorber for X-band frequency application

Stealth performance for any microwave absorbing material (MAM) is primarily controlled by the intrinsic characteristic properties of the composition of the composite. The inbuilt property of graphene has enrich the interaction of electromagnetic waves (EMWs) when it is impregnated in its compatible components such as naturally occurring organic materials. The present research engraved with a natural fibre composite with graphene as a stuffing in a resin polymer environment. The powdered form of banana-coconut coir fibre dust with 50–50 wt.% of average particle size of 150 µm with graphene has been fabricated as a hybrid composite of Graphene/Banana-coconut (GN/BNN-CCNT). The surface morphology of the fabricated composite is significantly modified with the addition of graphene creating a sustainable and foam-like elastic skeletal structure for compatibility with EMW. The enhanced dielectric values with different microwave properties for stealth performance are computed. At a frequency of 10.63 GHz a significant −15.68 dB reflection loss is found which comprises of power loss of 97.5% showing the effectiveness of the GN/BNN-CCNT/Epoxy hybrid composite as a stealth material for different X band frequency applications.

Synthesis and characterization of novel hybrid composites using nanofiller-nanofibrous coating for industrial applications

Composite materials are gaining popularity because of their superior properties compared to traditional materials. However, further improvements can be made by adding nanoparticles as nanocoating and nanofiller with the composite materials for different industrial applications. In this study, a Kevlar fibre mat has been coated by nanoparticles. In addition to this, different nanofillers have also been added. Various mechanical, physical, morphological, and thermal characterization techniques have been performed to characterize the synthesized composites. Five different samples were made where graphenenanocomposites showed the highest mechanical properties in hardness, tensile, bending, and compression. Around 15%, 35%, 120% and 170% improvement was obtained in hardness, tensile, bending and compression due to graphene incorporation compared to the composite without nanopartilces reinforcement.The minimum void fraction was obtained from the sample prepared without nanoparticles, which was 2.9%. The nanocoated surfaces of the composites were smoother and had a better surface finish with the uniform distribution of nanoparticles. The addition of graphene and other nanoparticles increased the crystallinity and binding energy of the composites. Fourier Transformed Infrared Spectroscopy analysis identified the presence of different functional groups. The addition of nanoparticles increased the thermal stability significantly.

The influence of graphene admixture on strength properties of cement-based composites

Cement-based composites pose a long tradition in the construction industry and are used in various forms such as structural concretes, masonry and plaster mortars, injection and special mixtures for three-dimensional concrete printing. Fine granular composites intended for injection and printing activities may have increased tend to shrinkage and cracking. The application of nanomaterials may bring a partial solution to toughening of cement-based composites. For this reason, the effect of the addition of various amounts of graphene admixture up to 0.03 wt.% on the strength properties of fine granular cement-based composites was researched. All prepared fresh mixes had the constant w/c ratio, and the behavior of modified composites was compared with plain reference material. On hardened test specimens, compressive strengths obtained after 1, 7 and 28 days of curing time were evaluated. The experimental investigation revealed, on the one hand, the partial worsening of workability of fresh mixes being compensated with an increasing amount of a superplasticizer and, on the other hand, the increment of compressive strength up to 12.5 % even for specimens with the lowest addition of graphene.

Doping Effects of Carbon Nanotubes and Graphene on the Flexural Properties and Tribological Performance of Needle-Punched Carbon/Carbon Composites Prepared by Liquid-Phase Impregnation.

The main goal of this study is to investigate the doping effects of carbon nanotubes (CNTs) and graphene on the needle-punched carbon/carbon (C/C) composites that are prepared by liquid-phase impregnation. In order to achieve, for the C/C composites, the purposes of high flexural strength, stable friction coefficient, low weight loss, and high thermal conductivity, our primary concern is to examine the flexural properties and the tribological performance, and then to explore a little further into the influence on thermal conductivity. In this study, carbon fiber preforms were first fabricated by needle-punched carbon-fiber cloth, and then liquid-phase phenolic resin, doped with different proportions of carbon nanotubes and graphene, was used as the impregnation solution to carry out multiple densification (impregnation-carbonization) cycles and fabricate various C/C composites. The main purpose was to probe into the doping effects of the CNTs and graphene, added to the impregnation solution, on the properties of C/C composites. The experimental results show that the addition of CNTs and graphene can improve the heat conductivity, flexural properties, and tribological performance of C/C composites, and the impact on these properties is more significant with the addition. Furthermore, the properties of graphene-doped C/C specimens are better than those of CNT-doped C/C specimens.

Fracture Load Estimations for U-Notched and V-Notched 3D Printed PLA and Graphene-Reinforced PLA plates using the ASED Criterion

This paper addresses the estimation of critical loads in FFF (Fused Filament Fabrication) printed polymers and composites containing notches. Particularly, the analysis is focused on the fracture load estimations of 39 PLA (polylactic acid) and 39 graphene reinforced PLA (PLA-Gr) printed plates containing two different types of notches (U- and V-notches) and combining different plate thicknesses and defect length to plate width (a/W) ratios. The addition of graphene (1 wt.%) increases both the yield stress and the ultimate tensile strength, also reducing the strain at rupture and, thus, generating a material whose behavior is closer to linear elasticity. Among the different assessment tools that may be used to estimate critical loads, this work applies the well-known Averaged Strain Energy Density (ASED) criterion, which compares the averaged strain energy over a certain control volume at the notch tip with the corresponding critical value, the latter being a material property. This approach has a linear-elastic nature, so its application to non-fully linear materials may require the use of specific corrections or calibrations. For the two materials analyzed here, PLA and PLA-Gr, it has been observed that the ordinary linear-elastic ASED criterion provides good estimations for the PLA-Gr material, whereas the pristine PLA, with more evident non-linear behavior, the obtainment of accurate results requires a previous specific calibration of the ASED material parameters

Effects of the graphene/metal interface on elastic properties of Cu and W matrices: Molecular dynamics simulation

The present study aimed to investigate the effects of graphene/metal interface on the elastic properties of Cu and W matrices over a wide range of temperatures through molecular dynamics (MD) simulations. Results showed that the addition of graphene to Cu and W matrices can improve their Young's moduli, with higher enhancements observed at higher graphene fractions. The load transfer mechanism was employed to analyse the reinforcing effect of graphene in metal matrices, and the load transfer rates were subsequently calculated. The strengthening effect of graphene in Cu matrix was observed to increase significantly with rising temperatures, whereas that of G-W models decreased due to the decreasing load-carrying capacity of graphene at very high temperatures. Furthermore, the Poisson's ratio of Cu-based materials decreased with increasing strain, while that of W-based materials remained nearly constant. This behaviour can be attributed to the prominent surface effect of lateral stress and the crystal structure transformation observed in Cu-based materials. Notably, a negative Poisson's ratio was observed in G-Cu nanoplate when the vertical stress became compressive. Overall, this study provides insights into the elastic deformation behaviour of graphene/metal composites, which could help develop new graphene-reinforced Cu or W composites.

Graphene-based anode materials in Li-Ion batteries

Doubtlessly, one of the most used electric power storage technologies at the moment is the lithium-ion battery (LIB). Meanwhile, in order to meet increasing needs for the present LIB performance, the improvement on the anode materials of LIB is one of the major study approaches. Among a wide range of options like silicon, metal oxides, and other compounds and mixtures, this review will mainly focus on the graphene-related LIB anode materials. By discussing the preparation processes and the electrochemical performance of various types of graphene-based and graphene-coated materials that are used for the anode of LIBs, the improvements of the addition of graphene in other materials have been reviewed, and the patterns of that have been analysed. This review helps summarize the current typical research results of the electrochemical properties of LIB anode materials based on graphene and gives suggestions about the future research focus on this specific category of materials by referring to the comparison of the data reviewed.

Effect of oxidized graphene addition on diesel fuel quality parameters

The effect of oxidized graphene on the quality parameters of diesel fuel for transport was examined in this ‎study. The research covered base diesel fuel and diesel fuel containing an additive package. ‎Both tested fuels contained no biocomponent. The method of preparing a stable mixture of ‎graphene material in each tested diesel fuels was developed for research purposes. ‎Then, for the fuel samples prepared in this way, tests of quality parameters specified in EN ‎‎590 [1] were performed, and the test results were related to the criteria indicated in the ‎mentioned standard. For parameters where it was technically possible to perform the ‎determination, the results showed the influence of the graphene material on the content of ‎solid impurities, oxidative stability and lubricity. For fuel samples containing oxidized ‎graphene, the stability of the mixture under storage conditions was also examined.

Experimental investigation to assess the effect of graphene blended lithium grease on friction, wear, and surface morphology of 52100 chrome alloy steel contacts

AbstractThe results of a research on the tribological behaviour of lithium grease with the addition of graphene nanoparticles are presented in current work. Using a four‐ball tribometer, the wear and friction coefficient of lithium grease and blended grease samples with graphene additions were assessed. The significance of graphene in enhancing the tribological properties of grease materials is evident from experimental results. In the experimental investigation, a considerable decrease in wear and friction co‐efficient values was also noted. One weight percent addition of graphene to base grease decreases friction by 23.73% and wear scar width by 19.51%.

Advancement of thermoelectric performances through the dispersion of expanded graphene on p-type BiSbTe alloys

ABSTRACT We demonstrated the systematic investigation of the graphene addition on the microstructural behaviour and concurrent thermoelectric properties of water-atomized p-type BiSbTe (BST)- based alloy using mechanical ball milling, and followed through the spark plasma sintering to fabricate a bulk compact specimen. X-ray diffraction results confirm the single phase of BST. The fracture surface of both specimen exhibits the homogenous distribution of grains with irregular shapes in a random alignment. The graphene in the BST provides an extra carrier transport leading to an increment in the carrier concentration (n) resulting in higher electrical conductivity (σ) for the BST + Graphene composite. The interface between two-dimensional (2D) graphene and bulk BST provides a larger degree of phonon scattering leading to a maximum reduced thermal conductivity (к) of 0.8 W m−1K−1 compared to pristine- BST (0.9 W m−1K−1) results in a maximum figure of merit (ZT) 1.1 at 400 K.