Addition Of Graphite Particles Research Articles

A Macroscopic Interpretation of the Correlation between Electrical Percolation and Mechanical Properties of Poly-(Ethylene Vinyl Acetate)/Zn Composites.

Elastic composites were prepared using a procedure involving hot plates and zinc powder that was directly dispersed into an EVA matrix. The correlation between the zinc content and the conductive properties of the material was studied via impedance spectroscopy, the thermal properties of the material were studied via differential calorimetry and the mechanical properties of the composites were studied via tensile strength curves, representing an important advancement in the characterization of this type of composite material. The composites' tensile strength and elongation at break decrease with the addition of filler since zinc particles act as stress-concentrating centres, while the composites' hardness and Young's modulus increase because of an increase in the stiffness of the material. The AC perturbation across the EVA/Zn composites was characterized using an RC parallel equivalent circuit that allowed us to easily measure their resistivity (ρp) and permittivity (εp). The dependence of these electrical magnitudes on the zinc content is correlated with their mechanical properties across the characteristic time constant τp = ρp·εp of this equivalent circuit. The dependence of the mechanical and electrical magnitudes on the zinc content is consistent with the formation of percolation clusters. The addition of graphite particles increases their potential performance. Three possible mechanisms for the electrical transport of the ac-perturbation across the EVA/Zn composites have been identified. Chemical corrosion in acid media causes the loss of zinc surface particles, but their bulk physical properties practically remain constant.

An experimental study on the effect of graphite microparticles on the mechanical and tribological properties of epoxy matrix composites

This article comprehensively discusses the mechanical and tribological properties of epoxy matrix composites filled with 100μm graphite particulates, at loadings ranging from 0 to 1wt%. The investigation also focuses on the effects of the graphite filler on the wear surface of the specimens, utilizing an optical microscope for analysis. The results revealed a significant decrease in the tensile strength of the composite, with a reduction of more than 50% observed at 1wt% graphite loading. However, the flexural strength exhibited an initial sharp increase at 0.1wt% graphite loading, followed by a decline at higher graphite contents. Moreover, both impact and hardness values demonstrated improvement as the graphite content increased. The addition of graphite particles led to a reduction in the friction coefficient, attributed to the solid lubrication capabilities of graphite. Furthermore, the wear rate exhibited a sharp decrease with an increase in graphite content due to the formation of a lubrication layer at the contact surface, effectively reducing the break-off of the specimen.

Investigation of enhancing EDM machining performance of INCONEL alloy using composite electrodes

In this research, an attempt was made to reinforce aluminium with graphite particles and use it as a tool material with the objective of combining the properties of aluminium and graphite. The micrograph confirms that the graphite particles were uniformly distributed over the aluminium matrix, density reduces and thermal conductivity increases with the addition of graphite particles. Material Removal Rate (MRR) peaks at 12 A current before declining due to plasma channel expansion, an optimal Ton of 8 μs ws observed, with 4 μs Toff yielding higher MRR. Copper electrodes excel due to thermal conductivity, while 5% graphite in aluminum boosts MRR to 31.89 mm3 min−1, additional graphite decreases MRR. TWR rises with shorter Toff until 6 μs, then decreases. Gap control impacts TWR, with lower spark gaps causing higher TWR due to intense material removal, and higher gaps leading to increased TWR due to incomplete flushing. Copper electrodes have the lowest TWR due to their high melting temperature. The addition of graphite in aluminum reduces TWR at low currents but is less effective at higher currents. Surface roughness (Ra) decreases with higher current, reaching a minimum of 7.02 μm at 12 A. Optimal Ton is 8 μs (7.56 μm), while shorter Toff at 4 μs and a 3 mm gap yield the best Ra of 7.36 μm with A4 composite tool. Copper electrodes result in higher Ra at higher currents, while graphite in aluminum improves surface quality, especially at 5% content. Arcing, an undesirable electrical discharge phenomenon in EDM, adversely affects machining. Experiments revealed a strong correlation between high duty cycles, duty ratios, and arcing propensity, with composite tools being more susceptible due to their variable conductivity. In contrast, non-composite tools, exemplified by copper, withstand higher duty ratios without arcing.

Impact of micro graphite particles addition on the mechanical behavior of Al2011 alloy metal composites

AbstractMicron‐sized graphite particles additions to Al2011 alloy were investigated to know their impact on mechanical properties. The stir cast method was used to manufacture the Al2011 alloy with 2 and 4 wt% of graphite particles reinforced composites. The microstructural analysis and mechanical properties of the synthesized composites were tested. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectrums were used to characterize the microstructure of the samples that were obtained from the casting. SEM micrographs indicated the homogeneous distribution of particles and the EDS patterns confirmed the presence of graphite particles. Al2011 alloy hardness was decreased with the addition of graphite particles. Further, with the addition of 2 and 4 wt% of graphite particles in the Al2011 alloy, the ultimate tensile and yield strengths of composites were increased with increase in elongation. SEM micrographs of tensile fractured surfaces were used to study the various fractured behaviors in the Al2011 alloy‐graphite composites.

Influence of graphite particles in UV-curable corrosion protection coating from palm oil based urethane acrylate (POBUA)

Replacing petroleum oil with renewable sources from natural oil in producing polymer coating is being widely attracting many researchers and inventors. In this study, palm oil-based urethane acrylate (POBUA) coating was developed as a protective coating for mild steel by using the ultraviolet irradiation technique. The POBUA was synthesized by reacting acrylated palm oil and isocyanate via in situ intercalative polymerizations with the presence of hydroxyethyl acrylate and 4 methoxy phenol (4mph). Different loadings of graphite particles (0.1 wt%, 0.5 wt% and 0.8 wt%) were introduced into the POBUA with the presence of Irgacure 184 as the photoinitiator. The formulated coating resin was applied on the mild steel substrates and the overall performances were investigated using Fourier transform infrared spectroscopy , contact angle measurements, X-Ray Diffraction, thermogravimetric analysis, electrochemical impedance spectroscopy , and Field Emission Scanning Electron Microscopy . Meanwhile, Gel content extraction and Pendulum Hardness were done on the cured film to investigate the performance of the polymerized coating polymer. The obtained results exposed good distribution of graphite particles in the POBUA polymeric matrix will influence the overall performance of the POBUA coatings at POBUA + 0.5 wt% graphite. Infrared spectrum demonstrated the formation of the crosslinked network was not disrupted with the addition of graphite particles, while increment of crystallinity index and hardness observed. Meanwhile TAFEL polarization elucidate the present of graphite particles reduced the curable POBUA coating corrosion current density from 102.6 × 10 −6 to 27.3 × 10 −12 Acm −2 with decreasing of mild steel corrosion rate per year from 31.24mpy to 125.1 × 10 −6 mpy. However, morphology showed that the addition of high graphite content (0.8 wt%) increased the tendency to particles agglomeration. Nevertheless, the results obtained showed that the presence of graphite particles in POBUA is beneficial in improving the strength of the coating against surface degradation and corrosion. This research demonstrates that POBUA/Graphite curable coating has a good potential application in mild steel protection. • Anticorrosion study for palm oil-based urethane acrylate enhanced by graphite was carried out. • Graphite particles influences the corrosion behavior as shown in Tafel plot. • The strength of the coating against corrosion was enhanced with the presence of graphite. • Graphite particles enhanced charge transfer resistance R ct of POBUA. • The POBUA R ct increased from 0.92 × 10 6 Ω up to 9.253 × 10 6 Ω.

Experimental studies and regression analysis on mechanical properties of MMCs based zinc-aluminium alloys with graphite particles reinforcement

In recent years, zinc-aluminium (ZA) alloys have found increasing uses in several applications because these alloys exhibit a good combination of mechanical, physical and tribological properties along with low cost of fabrication. In order to further enhance some of the properties of non-ferrous alloys, many attempts have been made to produce MMCs with Al alloys, Mg alloys, Cu alloys and Ti alloys as the matrix materials. Literature on aluminum alloy composites suggests the effective use of graphite as a potent reinforcement. The absence of data on ZA alloys with graphite reinforcement was the stimulus for pursuing this systematic work. In this study, the results of the experimental investigation with varying graphite reinforcements on the mechanical properties of the popular ZA base alloys (viz., ZA8, ZA12 and ZA27) are reported. The casting trials were done using the stir casting technique. In all the cases studied, the UTS, YS and percentage elongation increased with increasing addition of graphite particles, while hardness decreases with graphite particles addition. ZA27 reinforced with 6% graphite exhibited the maximum improvement in UTS, YS, % E and least decrease in hardness. The lowest improvement in mechanical properties with graphite reinforcement was in the case of ZA8, while ZA12 showed an intermediate trend. Design of experiments (DOE) denotes the methodology of application of statistical techniques in experimentation. This has been attempted in this work, for the first time for the ZA alloy based composites. Proceeding further, multiple regression models have been worked out for the UTS, YS, %E, and BHN. Confirmation test results are in good agreement with the values predicted.

Effect of micro graphite particles on the microstructure and mechanical behavior of aluminium 6061 (Al-Mg-Si) alloy composites developed by novel two step casting technique

In the present research, the effect of micron sized graphite addition on the microstructure and tensile failure of Al6061 alloy has been studied. The Al6061 alloy metal matrix composites reinforced with 6, 9 and 12 varying weight percentages of graphite particles were fabricated by novel two step stir cast route which helps in improving the wettability of Al6061 alloy matrix with graphite particles. The synthesized composites were subjected to microstructural studies, density, hardness and tensile properties testing. Microstructural characterizations of obtained samples were carried out by SEM microscopy, EDS and XRD patterns. The occurrence of graphite particles were confirmed by the XRD patterns. The density and hardness of metal composites have been decreased with adding of graphite reinforcement, while the ultimate tensile strength and yield strengths were improved with the addition of graphite particles. There was increase in the elongation of the Al6061 alloy composite after the incorporation of the reinforcement. Various fracture mechanisms were observed in the Al6061-graphite composites using SEM.

Effect of graphite particulate on mechanical characterization of hybrid polymer composites

Quest for producing lightweight and biodegradable materials has encouraged researchers to replace synthetic fibers with natural fibers. Hence a study is made to investigate the effects of introducing secondary reinforcement (natural fibers), stacking sequence, and addition of graphite particles on the mechanical characteristics and water uptakes along with diffusivity of hybrid (glass\jute) composites. Different weight fractions of graphite particulates are incorporated into the epoxy to produce different samples having 4 plies for each sample by hand layup vacuum bagging method. The obtained specimens are subjected to various mechanical tests, water absorption tests as per the ASTM standards, and optical microscopy was used to study the fracture morphology of the samples. The results displayed that the properties are deteriorated a little with the addition of secondary reinforcement, however they have improved with the addition of graphite. E-Glass as skin layer and treated jute as core layer composite exhibits ameliorate tensile strength (201.5 MPa), compression strength (515.12 MPa), flexural strength (106.9 MPa), hardness (25 BHN). However highest impact energy of 26 J is recorded for the sample with jute as skin layer and E-Glass as the core layer. Water absorption tests revealed that the addition of graphite has reduced the water absorption in the hybrid samples.

Cutting performance evaluation of nickel-plated graphite Fe-based diamond saw blades

With the purpose of improving cutting efficiency, nickel-plated graphite particles with different concentrations were added to the Fe-based diamond saw blades (DSB) to investigate the effect of nickel-plated graphites on the cutting performance of DSB. Graphite particles can effectively improve the utilization rate of diamonds by weakening the matrix, creating cavities, forming a graphite lubricating film, and reducing the hot corrosion of diamond particles, thereby effectively improving the sharpness of the DSB. The results of the cutting tests on five different kinds of rock samples show that the DSB can obtain the optimal cutting performance when containing 2% nickel-plated graphite particles, and its average sharpness can increase by 29.89% while the loss of service life is reduced by 51.77%. In addition, the observation and analysis results of the microstructure confirm that plating nickel could effectively increase the ability of the matrix to hold graphite particles. This can effectively protect the matrix materials and the diamond particles on the working surface of the DSB, thereby reducing the loss of service life caused by the addition of graphite particles. Finally, it can be projected that the nickel-plated graphite Fe-based DSB can maximize its advantages when applied to cut the hard rock with large mineral particles.

Micro-Macro Acoustic Modeling of Heterogeneous Foams with Nucleation Perturbation

<div class="section abstract"><div class="htmlview paragraph">The properties of a polyurethane foam are greatly influenced by the addition of graphite particles during the manufacturing process, initially used as a fire retardant. These thin solid particles perturbate the nucleation process by generating bubbles in their immediate vicinity. A large body of work has focused on foams that are reasonably homogeneous. In this work, we propose a modeling approach for inhomogeneous foams that includes membrane effects and allows pore size distributions to be accounted for. The cellular structure of the foam is obtained through a random Laguerre tessellation optimized from experimental properties. The structure of real foam samples is analyzed using X-ray computed tomography and scanning electron microscopy, followed by image processing, to create three-dimensional, digital models of the samples. The corresponding effective material parameters, including the permeability, the tortuosity and the viscous characteristic length, are subsequently computed by applying a numerical homogenization approach. All the numerical data are presented, discussed and gauged against experimental results.</div></div>

Synthesis & analysis of mechanical and tribological behaviour of silicon carbide and graphite reinforced aluminium alloy hybrid composites

This article mainly focuses on development, characterization and tribological performance of aluminium alloy matrix based hybrid composite strengthening with silicon carbide and Graphite particles. The investigation is carry forward step by step starts with development of hybrid composite, study all the properties to insure its utility in automobile sector possible specially for cylinder blocks, pistons etc. All these are the areas where sliding wear plays a predominant role. Hence Investigation has been done on sliding wear characteristics of this composite developed by mechanical agitation casting route i.e. aluminium alloy strengthened by 3 wt% and 6 wt% of silicon carbide addition with constant 2 wt% graphite particles. To evaluate each and every parameter the test was performed at two sliding distances of 1256.56 m and 2513.27 m at sliding velocities 1.047 m/s and 2.094 m/s under three loading conditions i.e. 10 N, 30 N, and 50 N. All these tests were performed for 3 compositions of the Hybrid composite. Results clearly shows wear resistance obtained at maximum (6 wt%) silicon carbide with constant graphite. Mechanical tests along with characterization of composite are to be investigated. Maximum tensile strength 234.57 MPa and hardness 49.5 BHN noticed in 6 wt% SiC at constant Gr reinforced composite. Microstructure reveals the grain refinement with graphite particles addition and overall hardness of composite improves with up gradation of SiC weight percentage.

Wear Behaviour of Aluminium Matrix Hybrid Composites: A Review

This review focus on the effect of reinforcement and different manufacturing techniques on wear and mechanical properties aluminium matrix composites and hybrid composites. These materials have capacity to satisfying the demands of advanced engineering materials applications. These difficulties are satisfied due to improved mechanical properties, conventional processing technique and reducing fabrication cost of aluminium composites. In powder metallurgy, the crucial issue is the selection of sizes of the matrix and reinforcement powders, whereas a major challenge in liquid metallurgy is wettability between the reinforcement particles and molten alloy. The addition of Al2O3 particles in matrix increases the mechanical strength and wear resistance of composites. However, incorporation of these particles can reduce the wear performance of Al composites under severe conditions. The addition of graphite particles helps in the formation of a thick layer on the wear surface. It was found that the mechanical and wear properties of the single reinforcement composites are better as compared to pure aluminium and aluminium alloys regardless of the aluminium matrix composites fabrication technique. Further, it was also established that most of the hybrid composites demonstrate better mechanical and tribological properties as compared to single reinforcement composites. How to cite this article:Singh S, Gupta A, Sharma. Wear Behaviour of Aluminium Matrix Hybrid Composites: A Review. J Adv Res Mech Engi Tech 2019; 6(1&2): 13-22.

Improvement in frictional behaviour of SAE 15W-40 lubricant with the addition of graphite particles

The present paper discusses the use of graphite particles in the lubricant for enhancing the friction properties of lubricant. Graphite particles were produced using the ball milling methods and mixed with multi-grade SAE 15W-40 lubricating oil using a magnetic stirrer and ultrasonicator. The graphite mixed lubricant was tested for its frictional behaviour using a linear reciprocating tribometer. Experiments were performed at three load values with constant stroke length and frequency. It is observed that graphite mixed lubricant resulted in reduction in coefficient of friction (COF) values. For the considered operating parameters, there is 33–36% reduction in the COF values. The overall temperature generation during the testing was also low for the graphite mixed lubricant testing.

Study on Microstructure and EDAX Analysis of Al/SiC/Gr Hybrid Metal Matrix Composites

The objective of this endeavor is to investigate the influence of graphite particles addition to the Al/SiC composites manufactured by stir casting method. Al/SiC/Gr hybrid metal matrix composites are preferred replacement for single reinforced composites by virtue of strengthened mechanical and tribological properties. A layered SiC/Gr composite material is required in gas turbine combustor can. Al/SiC/Gr composites are required in bearings, and pistons due to selflubrication, low wear rate and less friction. The inclusion of both strong reinforcement like SiC and smooth reinforcement like graphite enhances hardness and wear resistance of aluminium composites. The reinforcement content of graphite was varied from 2.5 to 7.5 wt % in a step of 2.5 wt. The SiC was fixed at 5 wt. % for all the three specimens, and Al6061 was used as matrix base material. The microstructure and EDAX analyses were required for three samples of hybrid metal matrix composites. Vickers hardness and porosity decreases for Al/SiC/Gr hybrid composites when percentage of graphite content increases. A review of surface modification of Al/SiC/Gr was done to find the different materials used for coating hybrid composites.

Properties of microinjection‐molded polypropylene/graphite composites

In this study, polypropylene (PP) composites filled with two different types of graphite particles, that is, flake‐shaped synthetic graphite (SG) and low‐temperature expandable graphite (LTEG), were prepared by melt blending, followed by microinjection molding (μIM). The microparts had three consecutive zones with decreasing thickness along the flow direction (FD). Results showed that, in addition to the larger particle size, the in situ exfoliation of LTEG during melt processing is crucial to the overall enhancement of electrical conductivity when compared with their SG‐containing counterparts, as corroborated by morphology observations. Moreover, the preferential alignment of conductive particles favors the construction of conductive pathways along the FD. The melting and crystallization behavior for PP, PP/LTEG, and PP/SG materials, and samples from each section of the corresponding microparts were evaluated by differential scanning calorimetry. Results indicated that both the addition of graphite particles and the typical thermomechanical history of μIM (i.e., high shearing and cooling rates) experienced in different sections of the three‐step microparts influence the melting and crystallization behavior of the composites. POLYM. ENG. SCI., 59:1560–1569 2019. © 2019 Society of Plastics Engineers

Evaluation of Mechanical, Microstructure and Sliding Wear Characteristics of Different Al-Zn Alloy and Composite: A Comparative Research

Plain bearings are extensively used in many engineering application. The wear loss of bearing material is the one of the major parameter that affects the performance of bearing. In this investigation, four Al-25Zn alloy samples reinforced with silicon carbide and graphite content were fabricated using stir casting technique. The mechanical properties, microstructure and sliding wear characteristics of fabricated specimens were studied. Dry sliding wear characteristic of specimens was investigated using a pin on disc tribometer with EN24 shaft steel disc at three speeds 1.0472m/s, 2.0944m/s and 3.1416m/s and three different applied pressures 0.3747MPa, 0.7584MPa and 1.1421MPa as per Taguchi L9 orthogonal array. The microstructure examinations of the worn surfaces were carried out using a scanning electron microscope (SEM). The hardness, tensile strength and wear resistance of Al-25Zn alloy with the addition of silicon carbide particles is found to be increased. The addition of graphite particles in Al-25Zn alloy enhances the wear resistance and tensile strength of the composite, in spite of the substantial decrease of hardness. The worn surfaces show the presence of delamination and abrasive wear mechanisms in the localized region.

Type and concentration effects of particulate solid lubricants on the microstructure, friction, and wear of electrodeposited Ni composite coatings

Nickel–MoS2 composite coatings were obtained by electrodeposition from a nickel electrolyte containing suspended MoS2 particles. The coating composition, morphology, crystalline structure, microhardness, and frictional behavior were studied as a function of MoS2 concentration. The results obtained in this study revealed that the codeposited lubricant particles strongly influenced the composite nickel coating properties. It was found that increasing codeposited MoS2 decreases the average grain size of nickel crystallites and leads to the formation of clusters which, in turn, lead to rough coatings with a high and variable thickness. The results of tribological response indicated that the reduction of friction coefficient and the improvement of wear resistance were performed until an optimal value of MoS2 concentration, which provided the best condition that promoted the tribo-layer stability and maintained the matrix integrity. A comparison of tribological and micromechanical properties between the coating containing the optimal fraction of MoS2 particles and the coating containing nearly the same fraction of graphite particles has been undertaken. Unlike the case of the addition of graphite particles, the microhardness of composite coating has been enhanced with the incorporation of MoS2 particles. However, the incorporation of graphite particles in the coating induced more effective lubrication and wear resistance.

Mechanical and thermal behavior dependence on graphite and oxidized graphite content in polyester composites

The influence of 0.1, 0.25, and 0.5 wt% of graphite and graphite oxide on the thermal and mechanical behavior of a PP-70 polyester resin was analyzed. According to the infrared spectra, the addition of graphite particles reduce the intensity of the ester groups reflecting a physical interaction between the filler and the polymer. The thermogravimetric analysis revealed a slightly increase in the decomposition temperature from 400 to 415 °C when 0.25 wt% of graphite oxide particles were incorporated. Dynamic-mechanical analysis behavior of polymer composites showed low interaction of graphite particles with polyester matrix, which changed the thermo-mechanical stability of composites. The flexural behavior for the two composites, obtained from stress-strain curves, showed that incorporation of 0.5 wt% of graphite and graphite oxide reduces the stiffness from 2700 to 2100 and 2250 MPa; in addition, the strength was also decreased from 98.1 to 68.2 and 63.5 MPa; respectively.

Pressure Influence on the AlCrFeNiMn/Graphite High Entropy Composite Microhardness

During the last years, mechanical alloying technique for high entropy alloys (HEAs) has been more often approached due to the good homogenous chemical distribution and near net shape technology provided by the respectively process. A new composite material having the matrix as HEA reinforced with graphite particles was designed. The graphite particles addition in the high entropy matrix (AlCrFeNiMn) improves the particles weldability during mechanical alloying and assures a good creep behavior for the final product. The aim of this paper is to investigate the pressure influence on the microhardness as dependence of sintering parameters which can be reflected also on the microstructure. The high entropy composite was completely alloyed after 40 hours of milling. The obtained composite was pressed using different pressures values in order to investigate the pressure influence on the microhardness and microstructure. The samples were investigated using optical microscopy, scanning electron microscopy, X-rays diffraction and microhardness tests. The microhardness values for all the samples were between 300 – 700 HV.

Cooling Curve Analysis of Micro- and Nanographite Particle-Embedded Salt-PCMs for Thermal Energy Storage Applications

In recent years, the focus of phase change materials (PCM) research was on the development of salt mixtures with particle additives to improve their thermal energy storage (TES) functionalities. The effect of addition of microsized (50 μm) and nanosized (400 nm) graphite particles on TES parameters of potassium nitrate was analyzed in this work. A novel technique of computer-aided cooling curve analysis was employed here to study the suitability of large inhomogeneous PCM samples. The addition of graphite micro- and nanoparticles reduced the solidification time of the PCM significantly enhancing the heat removal rates, in the first thermal cycle. The benefits of dispersing nanoparticles diminished in successive 10 thermal cycles, and its performance was comparable to the microparticle-embedded PCM thereafter. The decay of TES functionalities on thermal cycling is attributed to the agglomeration of nanoparticles which was observed in SEM images. The thermal diffusivity property of the PCM decreased with addition of graphite particles. With no considerable change in the cooling rates and a simultaneous decrease in thermal diffusivity, it is concluded that the addition of graphite particles increased the specific heat capacity of the PCM. It is also suggested that the additive concentration should not be greater than 0.1% by weight of the PCM sample.