Addition Of Graphite Research Articles

A comparative study relating machining properties and surface characteristics of Inconel 625 during powder mixed electric discharge machining

In the current study, the machinability during the machining with powder mixed electric discharge machining was studied on Inconel 625 sample along with their surface characteristics. During the machining, separatelythree powders viz. titanium, graphite and silicon carbide were mixed in EDM oil dielectric fluid with a concentration of 4 g/l. The other electric parameters were kept constant. The comparative study was made to study the changes in MRR, surface roughness and tool wear rate. The analysis clearly indicates that. by the addition of titanium, graphite and silicon carbide in the order, the MRR decreases, surface roughness increases and tool wear rate increases. The SEM results of the machined sample indicate that the surface unevenness is increasing with changing of powders. The EDX result of the surface correlated the amount of copper transferred to the surface and the tool wear rate . Like the SEM result, EDX result also indicated the enhancement of the tool wear during the machining of above-said order of the powders.

AZ91D合金射出成形品の金属組織，機械的性質および熱的性質に及ぼすグラファイト添加の影響

AZ91D合金射出成形品の金属組織，機械的性質および熱的性質に及ぼすグラファイト添加の影響

Optimizing the thermophysical properties and combustion performance of biodiesel by graphite and reduced graphene oxide nanoparticle fuel additive

In this study, 50 and 75 ppm reduced graphene oxide and graphite nanoparticle additives were added to cottonseed oil methyl ester which was obtained by the trasterification method. The effects of the related nanoparticle additives on fuel properties such as viscosity, lower heating value, density and cetane number were determined, and their effects on engine performance and exhaust emissions were experimentally investigated. The superior properties of reduced graphene oxide such as superior conductivity, high reactivity and large surface area to engine performance and emissions were experimentally investigated and presented the in this paper. The results indicated that, brake thermal efficiency increased in NPs additive added fuels by 6.92 % in CGt-50, 11.89 % in CGt-75, 14.35 % in CGn-50 and 17.97 % in CGn-75 fuels, respectively compared to C0 fuel at full load. Brake specific fuel consumptions decreased by 6.92 %, 11.25 %, 13.36 and 16.28 %, respectively. At 8 Nm load, the cylinder pressures of nanoparticle added fuels increased between 1.91 % and 5.16 % compared to base fuel. It was concluded that the heat release rate increased with the increase of the NPs additive ratio. Between the rate of 2 %-5.09 % reducing were obtained in ID, 0.84 %-5.85 % in CD for CGt-75 and CGn75 fuels according to C0 fuel. Compared to C0 fuel, CO emissions decreased by 9.48 %, 11.85 %, 14.23 % and 14.99 %, consecutively, in CGt-50, CGt-75, CGn-50 and CGn-75 fuels at full load. Thanks to the nanoparticle additive, the thermophysical properties and heat transfer rate of the fuels improved and the fuel mixture was stabilized, leading to an improvement of 8.98 %, 11.79 %, 14.04 % and 15.73 % in HC emissions, respectively. The NPs additive increased the cylinder temperature by 10.59 %-17.72 %, which enhanced NOx emissions. It was also observed that smoke emissions were reduced by 8.57 %-18.09 %.

Effect of water saturation on the electrical properties of cement and alkali-activated slag composites with graphite conductive admixture

This study investigated the influence of water saturation degree on the electrical properties of two different types of building materials – Portland cement and alkali-activated slag mortars with graphite powder as a conductive admixture. The graphite content ranged between 0 and 18 wt% of the cement/slag in order to cover the area below as well as above the percolation threshold. The properties were tested in terms of electrical resistivity measurement with an AC-frequency in the range of 40 Hz – 1 MHz, and the results were correlated with meso-scale structural changes evaluated by means of mercury intrusion porosimetry and scanning electron microscopy. The electrical resistivity of both materials decreased with increasing AC-source frequency and increasing water saturation degree. In a dry state, alkali-activated slag exhibited approximately ten times lower resistivity than cement-based material. The addition of graphite gradually decreased the resistivity until the percolation threshold was reached, but no influence of moisture on the resistivity was observed at dosages exceeding 12 wt% of graphite. The dependence of electrical resistivity on the water saturation degree was fitted for two different frequencies (50 Hz and 1 kHz) using a sigmoidal regression function.

Study on using graphene and graphite nanoparticles as fuel additives in waste cooking oil biodiesel

• Graphene and graphite nanoparticle additives showed lower NO emissions and higher thermal efficiency. • Graphene and graphite nanoparticle additives showed lower BSFC than neat biodiesel fuel. • At full load, both nanoparticles showed similar heat release as compared to neat diesel operation. • The combustion characteristics of fuel blends with graphite additives outperformed that of those with graphene additives. Utilising waste cooking oil biodiesel in internal combustion engines for power generation and transport is of increasing importance, as it is the least pollutant disposal method for waste cooking oil. Besides, researchers have recently shown an increasing interest in utilising graphene and its derivatives in different applications due to its unique thermal and physical characteristics, including enhancing the combustion characteristics of biofuels. Therefore, this article studies the characteristics of waste cooking oil biodiesel blended with few-layered graphene and graphite nanoparticles additives and their influence on combustion and engine emissions and benchmark them against neat biodiesel and diesel fuels. The biodiesel was synthesised through a transesterification method from waste cooking oil and blended with diesel or butanol after adding few-layered graphene and graphite nanoparticles. Few-layered graphene and graphite nanoparticle additives led to greater peak in-cylinder pressure by 0.5–2.5% increment and 1–4% lower heat released rate at full load. As such, employing few-layered graphene and graphite in a fuel mix reduced NOx emission by 0.7–5 % compared to 100% diesel counterpart. Besides, at full engine load, waste cooking biodiesel blended with 100 ppm few-layered graphene and graphite nanoparticles showed an increment in brake thermal efficiency by 8–10% compared to pure fossil diesel and waste cooking biodiesel. The results show the feasibility of using graphene-based nanoparticle additives in biodiesel to enhance biodiesel fuel combustion characteristics, hence lowering NOx emissions.

MECHANICAL AND TRIBOLOGICAL CHARACTERIZATION OF HYBRID Al6061/B4C/Gr COMPOSITES BY STIR CASTING TECHNIQUE

This research focuses on the fabrication of Al6061/B4C/Gr metal matrix composites as well as the mechanical and wear properties analysis. A liquid metallurgy stir casting process was used to cast the Al6061 alloy matrix composites with specific wt.% of B4C and constant wt.% of graphite. In this work, newly developed composites of Gr (particle grain size: 0–20[Formula: see text][Formula: see text]m) and B4C (particle grain size: 0–30[Formula: see text][Formula: see text]m) are reinforced with Al6061 pure alloy, which enhanced the mechanical and wear properties when compared to Al6061 pure alloy. Microstructure analysis was carried out concerning the developed mechanical properties. Furthermore, the dry sliding wear behavior of Al6061/B4C/Gr metal matrix composites was investigated at a sliding speed of 1[Formula: see text]m/s and a sliding distance of 1500[Formula: see text]mm against a hardened EN-31 disc under the corresponding load of 19.68[Formula: see text]N. The minimum wear rate is [Formula: see text][Formula: see text]mm3/m found at 15[Formula: see text]wt.% B4C and 2[Formula: see text]wt.% graphite and the coefficient of friction is 0.54 that decreases with graphite addition, with the lowest value obtained with 5[Formula: see text]wt.% B4C and 2[Formula: see text]wt.% graphite. Al6061/10[Formula: see text]wt.% B4C/2[Formula: see text]wt.% Gr particles-reinforced composite material demonstrated the highest tensile and flexural strengths. The hardness,compressive and tensile strength of the Al6061/15[Formula: see text]wt.% B4C/2[Formula: see text]wt.% Gr particles-reinforced composite material were the highest. Scanning electron microscopy was used to examine the worn surfaces of wear specimens. The main objective of this work is to develop hybrid Al6061/B4C/Gr composites with improved mechanical and wear properties when compared with the base alloy. Al6061 is widely used in automobiles parts like engine block, piston rings, alloy wheels, marine industries, etc. B4C used in the composite improves strength and is used commonly in armed bullet proof. The Gr present in the composite improves wear resistance, and therefore applied in wear-resistant parts like brake, piston with cylinder, etc.

Analysis of energy utilization for microwave-induced discharge of spherical biomass-derived char with graphite addition

Microwave discharge is a highly potential method for the use in energy and environment fields, and microwave-induced discharge of carbon-based dielectrics is proved to be advantages in terms of material cost, discharge duration and dielectric reuse, compared with microwave-induced discharge of metal. However, the energetic study of microwave-induced discharge of carbon-based dielectrics is poorly understood. Therefore, various dielectrics including bio-char, graphite and mixture of bio-char/graphite were shaped into spherical dielectrics (SB, SG and SBx) in the work, and then the detailed energetic analysis on microwave-induced discharge of spherical carbon-based dielectrics was performed via decouple of total heat (QT) into heat from dielectric microwave absorption (QA) and heat (QH) from discharge sites. The results showed that the contribution of QH to QT was maximized at 21.7% and 36.7% within 20 min, respectively for SB and SG. The heat and exergy efficiency for microwave-induced discharge of SG reduced by about 14.07% as the power increased from 240 W to 480 W. The heat efficiency of microwave discharge still rose by 13.2%–14.9% in case of SG, compared to shielded discharge. The study can provide valuable evidence for optimization of microwave-induced discharge of carbon-based dielectrics.

Graphite-enhanced thermal properties of octadecylamine/graphite foam shape-stable composite phase change materials for thermal energy storage

In this study, octadecylamine/graphite foam composite phase change materials (ODA/GF CPCMs) were prepared by vacuum impregnation; octadecylamine (ODA) was used as the phase change materials (PCMs), and graphite foam (GF) was used as the support material. Polyurethane (PU) foam obtained after hydrolysis in 40 wt% NaOH solution at 80 °C for 30 min was the template for the GF; therefore, the prepared GF has many interpenetrating pore structures, providing many adsorption sites for PCMs. For the ODA/GF-3 CPCMs with 15 wt% graphite addition, the loading of ODA is as high as 92.3%, the thermal stability is excellent, the melting temperature is 52.1 °C, and the latent heat of fusion is 218. 1 J/g, which is 1.1 times that of pure ODA. The thermal conductivity of ODA/GF-3 CPCMs is 0.725 W/m•K, which is 2.2 times that of pure ODA. These results indicate that ODA/GF CPCMs have good thermal properties, and their competitiveness in the field of energy storage is greatly improved due to their excellent performance.

Effect of coating prepared using CuNiIn mixed with graphite and MoS2 on fretting wear behaviour of Ti6Al4V

• Graphite and CuNiIn were plasma sprayed onto Ti6Al4V to get self-lubricating coating. • Addition of graphite to CuNiIn powder reduced the friction coefficient in fretting. • Presence of MoS2 at the contact surface further reduced the friction coefficient. • Effect of MoS2 at the contact surface was significant in CuNiIn + Graphite coating. In the present study, solid graphite was mixed with CuNiIn powder and plasma sprayed onto Ti6Al4V to develop a self-lubricating coating (CuNiIn + Gr). Fretting wear experiments were done at room temperature on uncoated Ti6Al4V samples and samples coated with CuNiIn + Gr composite powder and CuNiIn powder. The counterbody used was alumina ball. Inclusion of graphite in CuNiIn reduced the friction coefficient owing to graphite acting as a self-lubricant. To study the effect of solid lubricant MoS 2 , some tests were done after applying MoS 2 on the surface of the samples. The presence of MoS 2 reduced the friction coefficient in all samples. The reduction was more in CuNiIn + Gr coated samples, which can be related to the synergetic effect of both the solid lubricants.

Sn‐based glass–graphite‐composite as a high capacity anode for lithium‐ion batteries

AbstractSn‐based anode has been widely studied because of its high theoretical specific capacity. However, the capacity of Sn‐based anode decreases sharply during the cycle, which hinders its application in commercial batteries. In this paper, Sn‐based glass was successfully obtained by melt quenching method. Sn‐based glass and graphite were combined by the ball milling method as anode materials. The Sn‐based glass–graphite‐composite anode can still maintain the capacity of 700 mA h g−1 after 500 cycles at 500 mA g−1, which is about 2.7 times that of the Sn glass anode (260 mA h g−1) under the same test conditions. The addition of graphite can effectively inhibit the accumulation of Sn particles in the discharge process of Sn‐based glass anode, which improves the capacity of Sn‐based glass anode, and the addition of graphite can effectively reduce the resistance of Sn‐based glass anode. Therefore, the Sn‐based glass–graphite‐composite anode has excellent Li+ ions storage properties.

Towards engineering application: Integrating current strategies of promoting direct interspecies electron transfer to enhance anaerobic digestion

The study present here was to integrate the current engineering strategies of promoting direct interspecies electron transfer (DIET), ethanol-type fermentation pretreatment, and conductive materials (zero-valent iron [ZVI] and graphite) supplemented, to strengthen the anaerobic digestion of kitchen wastes. Experimental results imply that after ethanol-type fermentation pretreatment, ZVI and graphite supplemented could significantly improve the methane production, transformation efficiency of organic matter, as well as impact resistance ability of systems during anaerobic digestion of kitchen wastes with a gradual increase of organic loading rate. The sludge with ZVI and graphite addition had a relatively higher capacitance and lower resistance than that without ZVI and graphite. With the concentration ratio of ZVI and graphite increasing, the evidently increased abundance of electrotrophic methanogens, Methanosarcina acetivorans, and Methanospirillum hungatei suggested that ZVI stimulated the growth of electrotrophic methanogens. Together with the enrichment of exoelectrogens capable of extracellular electron transfer (e.g., Streptococcus, Petrimonas, and Syntrophomonas species) in the presence of ZVI and graphite, the DIET between these exoelectrogens and electrotrophic methanogens might be responsible for the improved performances and stability.

Effect of blowing agent content on the structure and flame‐retardant properties of rigid polyurethane foam/expanded graphite composites

AbstractDriven by global environmental issues, the development of green building materials has become an immediate focus. In this work, n‐pentane was used as an environmentally friendly blowing agent to prepare flame‐retardant rigid polyurethane foam (RPUF) with the addition of expandable graphite (EG) successfully, and the effect of n‐pentane content on flame retardancy and compressive properties of RPUF/EG composites was investigated through limit oxygen index (LOI), vertical burning test (UL‐94), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and compressive properties test. SEM results show that the content of EG and n‐pentane causes a change in the cell structure of RPUF. The change of the n‐pentane content has also an obvious effect on the thermal stability, flame retardancy, and specific compressive strength of RPUF/EG composites. In addition, the cell structure of RPUF matrix has an obvious influence on the distribution of EG in the composites, which indirectly affects the flame‐retardant efficiency of EG. This research explores the conditions for the application of environmentally friendly RPUF and expands its application prospects.

Characteristics and mechanism of microwave-induced discharge of spherical bio-char with graphite addition

The enhancement of efficiency converting microwave energy into heat has become great concern on industrial application of microwave heating. Microwave discharge can generate more hot spots, exhibiting more intense thermal effect than microwave heating alone. Microwave discharge can be achieved by a variety of carbon-based dielectrics like bio-char, whose performances are highly dependent on graphite degree of the carbon-based dielectrics. Therefore, graphite addition into bio-char by mechanical mixing is promising to improve the discharge performance. However, there are few studies on characteristics of microwave-induced discharge by spherical bio-char with graphite addition, and kinetic analysis of microwave discharge is lacking. Moreover, the mechanism of microwave-induced discharge of spherical carbon-based dielectrics has not been fully clarified. As a result, the work firstly studied characteristics of microwave-induced discharge of spherical bio-char with graphite addition. The other focus of this work was to explore mechanism of microwave-induced discharge through electric field simulation. The results revealed the average discharge intensity of spherical graphite in the first 20 min was 38.2 % higher than that of spherical bio-char. Microwave-induced discharge of bio-char with graphite addition had synergistic effect at the initial stage. It was obtained apparent activation energies of microwave-induced discharge of bio-char and graphite were 237.08 W·g−1 and 48.42 W·g−1, respectively. The formation of electric field polarization focuses offered active sites for microwave discharge. The work is of significance for fundamental research about microwave-induced discharge of carbon-based dielectrics.

Development of a ceramic membrane for emulsion water-diesel treatment

The purpose of this study was the development of a low-cost ceramic tubular membrane, using inexpensive materials, namely natural clay, and graphite as a porogenic agent. Such a low-cost membrane can be used as filters or porous supports for the preparation of multilayer ceramic membranes. Extrusion was used as a shape-forming method for this purpose. Graphite was selected as a porogenic additive. Raw materials were physicochemically and morphologically characterized. A comparative study of the influence of porogen content on membrane characteristics was carried out. Finally a graphite addition of 15 wt% and 850 °C as the sintering temperature were chosen. The obtained membrane had 41 vol% of porosity, diametral compression strength of 4 MPa, and relatively good corrosion resistance in basic and acid conditions. The performance of the membrane support was evaluated for diesel-in-water emulsion depuration as a function of pressure. Filtration test using 15% of porogen sample led to turbidity rejection factor of 95%. Therefore, it was considered that this membrane can be suitable for diesel/water emulsion treatment.

Metal (Cu/Fe/Mn)-Doped Silicon/Graphite Composite as a Cost-Effective Anode for Li-Ion Batteries.

Silicon is a worthy substitute anode material for lithium-ion batteries because it offers high theoretical capacity and low working potentials vs. Li+/Li. However, immense volume changes and the low intrinsic conductivity of Si hampers its practical applications. In this study, nano/micro silicon particles are achieved by ball milling silicon mesh powder as a scalable process. Subsequent metal (Cu/Fe/Mn) doping into nano/micro silicon by low-temperature annealing, followed by high-temperature annealing with graphite, gives a metal-doped silicon/graphite composite. The obtained composites were studied as anodes for Li-ion batteries, and they delivered high reversible capacities of more than 1000 mAh g−1 with improved Li+ diffusion properties. The full cells from these composite anodes vs. LiCoO2 cathodes delivered suitable energy densities for Li+ storage applications. The enhanced electrochemical properties are accredited to the synergistic effect of metal doping and graphite addition to silicon and exhibit potential for suitable Li+ energy storage applications.

The effect of graphite addition on thermal conductivity, microstructure, and electrochemical impedance spectroscopy of AlN ceramics

Graphite/aluminum nitride (AlN) multiphase ceramics are pressureless sintered under 1850 °C using Dy2O3 and CaF2 as sintering additives. The effects of added graphite on microstructure, thermal conductivity, and electrochemical impedance spectroscopy of AlN ceramics were investigated. It was found that with 1wt% graphite addition the thermal conductivity of AlN in the through-plane to can achieve 210 W/(m K), which 25% higher than that of AlN without graphite. The graphite addition eliminates the oxygen impurity in AlN by a carbon reduction reaction in form of nanosized Dy2O3 particles. From electrochemical impedance spectroscopy manifested that the activation energy (Ea,g) of samples in grains is increased from 0.784 to 1.112 eV, suggesting that the concentrations of defects and impurities of Graphite/AlN multiphase ceramics are lower than those of monophase AlN ceramics.Graphical abstract

Electrical resistance and self-sensing properties of pressure-sensitive materials with graphite filler in Kuralon fiber concrete

Abstract This study aimed to investigate conductivity behavior of concrete containing graphite and its sensitivity to the effects of pressure. Graphite powder was added to concrete to replace partial cement (4 wt.%, 8 wt.%, 12 wt.%, and 16 wt.%) as conductive fillers with a water-to-cementitious ratio of 0.45. Specimens with 0.5 vol.% Kuralon fibers were treated to enhance the performance of self-sensing properties to investigate the influence of graphite and fiber contents on electrical resistivities. The relationship between the axial load and changes in resistivity was determined using cyclic loading tests, indicating the existence and development of internal cracking in concrete. The results indicated that the compressive strength presented a linear decline proportional to the addition of graphite. Specimens with 8% graphite reached the lower bound of self-sensing properties, and with an increase in the amount of graphite, resistivity gradually decreased. In the cyclic loading tests, specimens containing >8% graphite were able to better reflect the relationship between loading and resistivity. Kuralon fibers in concrete had further improvement in resistance and self-sensing properties. In inclusion, the mixture with 8% graphite provided the best self-sensing properties to warn for preventing the effects of cracking, as well as achieved better mechanical properties.

Landfill leachate treatment by graphite engineered anaerobic membrane bioreactor: Performance enhancement and membrane fouling mitigation

Low efficiency of anaerobic digestion and membrane fouling, treating landfill leachate, are big barriers in the application of anaerobic membrane bioreactor (AnMBR). Anaerobic digestion enhancement and membrane fouling mitigation of AnMBR with graphite addition, treating landfill leachate, were investigated in this study. The effect of graphite on organics removal, biogas production, methane content in biogas, membrane fouling, microbial responses and foulant compositions were analyzed. With the graphite addition, chemical oxygen demand (COD) removal of 78% was achieved for influent COD concentration of 3000 mg/l, which was significantly higher than the stage without graphite addition (65%) for influent COD concentration of 2000 mg/l. Similarly, methane content in biogas with graphite addition was 56%, while without graphite addition it was 46%. These digestion improvements were due to the promotion of organics degradation, facilitated by direct interspecies electron transfer (DIET) mechanism via graphite addition in AnMBR. The graphite addition prolonged membrane cleaning cycle from 13 days to 30 days. Protein content in loosely bound extracellular polymeric substance (LB-EPS) was the main fouling agent, which decreased with the graphite addition. The main mechanism behind membrane fouling mitigation was the protein content reduction in LB-EPS, which was biodegraded by Trichococcus being increased in relative abundance with the graphite addition. Furthermore, abundance of Denitratisoma decreased in anaerobic sludge and its accumulation reduced on membrane surface, subsequently membrane fouling was mitigated. Overall, graphite addition in AnMBR is a potential eco-innovative approach that efficiently removes pollutants from landfill leachate, enhances biogas quality and mitigates membrane fouling.

Sintering behavior of the Ti(C,N)‐based cermets with graphite or diamond additives

AbstractCombining DSC/TG–QMS analysis and dilatometry experiments at constant heating rates, the sintering behaviors of the Ti(C,N)‐based cermets with carbon additives were studied. It is found that the additives of diamond or graphite could promote the interactions among raw powders during solid‐state sintering. The outgassing behavior and endothermic effect were enhanced, thereby resulting in the increasing densification activation energy. The negative activation energy during the liquid phase sintering indicates that the dissolution–precipitation process occurs easily and provides a rapid densification path. The dissolution–precipitation process for cermets with .6‐wt% graphite or .6‐wt% diamond additive became more efficient than for cermets without additional carbon additive. The white‐core/gray‐rim grains were clustered together in the cermets with .6‐wt% graphite additive, whereas they were distributed evenly in the cermets with .6‐wt% diamond additive. Moreover, the average sizes of ceramic grains in the cermets without additional carbon additive, and with .6‐wt% graphite or .6‐wt% diamond additives, were .453, and .517, or .525 μm, respectively.

Controlling the Solid-State Reaction in Fe-MoS2 Self-Lubricating Composites for Optimized Tribological Properties

In this work, self-lubricating composites containing MoS2 and graphite dispersed in an iron matrix were produced by powder metallurgy and sintering. Previous studies demonstrate that MoS2 reacts with iron matrixes during sintering, making the production of Fe-MoS2 composites rather difficult. Therefore, this study focused on a potential solution to avoid or reduce this reaction, whilst still providing good tribological properties. Our results show that the addition of graphite retards the reaction of MoS2 with iron and that the combination of MoS2 + graphite results in composites with an optimized coefficient of friction associated with a low wear rate both in nitrogen and air atmospheres. Through adequate control of the lubricant’s particle size, composition, and processing parameters, self-lubricating iron-based composites with a low dry coefficient of friction (0.07) and low wear rate (5 × 10−6 mm3·N−1·m−1) were achieved.