Addition Of Graphite Powder Research Articles

Investigation into the sheet metal forming process using solid granules medium with graphite powder addition

ABSTRACT The solid granules medium sheet metal forming process uses loose particles instead of a rigid convex mold in the deep drawing process. This study focused on a mixed medium of solid granules with added graphite powder , establishing numerical models for four different proportions of graphite powder-solid granules mixtures. A finite element simulation of deep drawing was conducted using 08AL sheets. A deep drawing test shows that the thickness distribution curve closely aligns with the numerical simulation. By adding graphite powder to the solid granules medium, the lubrication conditions between the granules and the sheet metal can be modified, increasing the thickness in the fracture-prone areas of the cylindrical part. Utilizing this numerical model yields thickness distribution and deformation characteristics that closely resemble those observed in deep drawing tests, thereby contributing significantly to the optimization and advancement of this forming technology.

HaptiYarn: Development of an Actuator Yarn That Can Transform Everyday Textiles Into Haptic Devices.

A method of providing localised haptic feedback at precise locations on the body, utilising a lightweight textile garment is presented in this short paper. The textile comprises of subtly integrated actuator yarns (HaptiYarns) which are controlled by electropneumatic circuitry. Each yarn has two functional layers, an inner porous textile layer with limited extensibility and a second, durable outer layer made from an extensible elastomer. The HaptiYarns can provide radial forces and a maximum radial displacement of 28.09 ± 0.14 mm. It was found that the intrinsic addition of graphite powder (5% by weight), during elastomer preparation, offered better resistance to layer delamination and increased the ability of the yarn to withstand higher internal air pressures by 48%. Both the graphite-filled composite and the graphite free yarns demonstrated high durability, withstanding cyclic testing of >7500 cycles while having no significant impact on the force feedback. Finally, a wearable prototype knitted textile garment is presented with eight HaptiYarns subtly integrated within it and connected to a virtual reality (VR) program providing an immersive haptic experience. These yarns offer the potential to transform everyday clothing into wearable haptic devices with potential to revolutionise healthcare, VR-based training, gaming, and entertainment sectors.

Experimental research on the effect of graphite on heat transfer performance of a latent heat storage system

Phase change materials (PCMs) provide a good resolution for the latent heat storage system which can be used in many application fields such as solar energy utilization and waste heat recovery. This study aims to experimentally investigate the impact of graphite powder on the thermal characteristics and heat transfer performance of paraffin with ceresin (PC) as a PCM, using water as the heat transfer fluid. Experimental tests were conducted to analyze the heat transfer performance of PC and the influence of graphite powder on its thermal characteristics. Different masses of graphite powder were employed to assess their effects on the heating rate and the time required for PC to reach its melting temperature. The experimental results revealed that the addition of graphite powder improved the heating rate of both PC and water, attributed to its high thermal conductivity. Furthermore, the time for PC to reach the melting temperature was decreased with varying amounts of graphite powder, achieving a maximum reduction of 17.2% with the addition of 40 g of graphite powder. However, the effectiveness of graphite powder in enhancing heat transfer efficiency was found to be limited, with the optimal promotion effect observed at around 40 g of graphite powder for 500 g of PC. The findings of this investigation provide valuable insights for the design of phase change energy storage systems, with potential applications including heat pump drying units, greenhouse energy storage in modern agriculture, and solar energy storage utilization technology. The theoretical basis established can contribute to the development and optimization of PCM-based systems in diverse practical scenarios.

Effect of Graphite Powder Addition on Microstructure and Room Temperature Mechanical Properties of Ti-45Al-8Nb Alloys

The enhancement of the mechanical properties of TiAl alloys through the introduction of a second-phase reinforcement is highly essential. In this paper, using graphite powder as a carbon source, the Ti2AlC phase is introduced to improve the compression and friction properties of the TiAl alloy. Concurrently, the effects of graphite powder additions on the microstructure and room-temperature mechanical properties of Ti-45Al-8Nb-xC (mass%) alloys are investigated. The results show that as the volume fraction of Ti2AlC and the interdendritic γ phase increases, the length–diameter ratio of the Ti2AlC phase decreases with increases in the graphite powder addition. The addition of graphite powder results in a refining effect on the grain size and lamellar spacing of the Ti-45Al-8Nb-xC (mass%) alloys. As the graphite powder content increases from 0 to 0.9 mass%, the microhardness increases from 557 HV to 647 HV. The room-temperature compressive strength and strain of the Ti-45Al-8Nb-xC (mass%) alloys first increase and then decrease with the addition of graphite powder. Specifically, when the content of graphite powder is 0.6 mass%, the alloy exhibits a maximum compressive strength and strain of 1652 MPa and 22.2%, respectively. Compared with the alloy without the graphite powder addition, the compressive strength and strain are improved by 37.7% and 62.1%, respectively. The wear resistance of the alloys is improved through the addition of graphite powder and the wear rate decreases from 5.062 to 2.125 × 10−4 mm3·N−1·m−1 as the content of graphite powder increases from 0 to 0.9 mass%.

Experimental Investigation of the Machining Characteristics in Graphite-Powder-Mixed Electrochemical Discharge Machining of Microholes in Glass.

The effect of graphite powder on the machining characteristics in graphite-powder-mixed electrochemical discharge machining of microholes was still not clear. How the discharge mechanism changed with the addition of graphite powder into the electrolyte, which further led to changes in the morphology of the machined holes, remained to be revealed. In this study, a series of microhole machining experiments were conducted in glass. Comparisons of the discharge energy, microhole entrance diameter, hole taper, and tool electrode morphology after machining were made when machining in the electrolytes with and without graphite powder. Experimental results revealed that there were a lot of small pulse currents distributed on the current waveform when machining with the graphite-powder-mixed electrolyte. The average discharge energy of the small pulse current was 2.8 times as much as that of the general electrochemical discharge. After introducing graphite powder into the electrolyte, the entrance diameter of the hole became larger when the hole depth was deeper than 200 μm. The HAZ width increased with increasing hole depth at the voltage of 37-41 V, while it decreased at the voltage of 43 V. A reduction in hole taper angle with a range of 0.5° to 2.3° was achieved. In addition, after machining in electrolytes with and without graphite powder, the tool electrode surfaces showed different morphologies due to different discharges.

Temperature effects and a prediction method of field-dependent yield stress in graphite magnetorheological grease

Graphite additives have become increasingly prevalent in magnetorheological (MR) materials, as they can substantially improve the shear yield stress of such materials. However, the effect of graphite additive proportion and temperature on graphite magnetorheological grease (GMRG) has not yet been fully reported, which limits the engineering application of GMRG. This work prepared magnetorheological greases with five different graphite ratios and investigated how their steady-state shear properties responded to temperature. The shear yield stress and relative MR effect of GMRG at different magnetic field strengths were measured and calculated. The results verified that the yield stress of GMRG increased with the increase of graphite additive ratio, but the relative MR effect decreased significantly. Besides, the steady-state shear mode was employed to evaluate the rheological properties of GMRG under varying magnetic field strengths and temperatures. The yield stress was analyzed through fitting experiments conducted under different magnetic field strengths and temperatures. The results showed that the addition of graphite powder increased the shear yield stress of the GMRG. But the enhancement effect was weakened by increasing temperature. In addition, a support vector machine (SVM)-based prediction method was proposed to predict the performance of GMRG with different ratios under complex operating conditions. The SVM-based estimation results showed good agreement with actual experimental values. This method provides a new approach for proportioning, characterization, and performance prediction of other materials.

Development and investigation of form-stable and cyclable decanoic acid-based composite phase change materials for efficient battery thermal management

Phase change material as the core of latent heat energy storage technology, suffers from the “solid-liquid phase change” problem. In this study, “solid-solid” composite phase change materials (CPCMs) have been developed using olefin block copolymers (OBC) and decanoic acid. With ≥30 wt% OBC, the physical shapes of the developed CPCMs nearly remain unchanged after 100 times of thermal cycling, without significant changes in the phase change properties. The addition of graphite powder leads to a significant enhancement in thermal conductivity of up to 18 times, which leads to excellent control of battery maximum temperature and temperature uniformity. In the battery thermal management test, the developed CPCM achieves a maximum of 3 °C and 10.5 °C reductions in maximum temperature difference and peak temperature, respectively. The CPCMs also prolong the thermal preservation time by 3 times. In the pack level test, the use of CPCM plates leads to a maximum temperature reduction of 15 °C on the commercial battery pack under 55 °C extreme working temperature.

Grain growth and phase transformation of nano-sized titanium dioxide powder during heat treatment and spark plasma sintering

The control of nanostructures is crucial for enhancing the thermoelectric properties of materials. In this work, the grain growth and phase transformation of different nano-sized titanium dioxide (TiO2) powders were investigated during heat treatment and spark plasma sintering. First, the thermal behaviors of TiO2 powders with different particle sizes during heat treatment, such as grain growth, phase transformation, and adsorption properties, were studied. The results showed that the phase transformation of 7 nm anatase TiO2 occurred more easily, and the rutile phase content increased with increasing heat treatment temperature. The grain growth of 7 nm anatase TiO2 occurred at low temperature (i.e., 873 K), even the grain size increased by 13-fold at 1123 K (i.e., the phase transformation temperature). Thermogravimetry results suggested that the 7 nm anatase TiO2 powder had a greater adsorption characteristic owing to its large specific surface area. Moreover, TiO2 compacts with and without graphite were fabricated using spark plasma sintering. The results indicated that a lower sintering temperature was beneficial for maintaining the nanostructure, whereas the addition of graphite powder promoted grain growth. Furthermore, the thermal conductivity was reduced owing to the nanostructure, and the phonon thermal conductivity accounted for a dominant proportion of the total thermal conductivity. Consequently, the lowest thermal conductivity was 1.1 Wm−1K−1 at 973 K for the nanostructured compact sintered at 1073 K, which is approximately 50% lower than that of the microstructured compact sintered at 1273 K.

Corrosion effect on reinforced concrete with the addition of graphite powder and its evaluation on physical-electrochemical properties

The corrosion of reinforced concrete without and with the addition of graphite powder with low carbon content was evaluated. Phase identification processes and physical-electrochemical properties of the concrete were analyzed using X-ray diffraction techniques (XRD), scanning electron microscopy (SEM), half-cell potential, electrochemical noise (EN) and linear polarization resistance (LPR). Samples were studied for 168 days in saline solution. The results show that, when adding graphite powder in an amount of 2.5% by weight of cement, the compressive strength increased if compared with the control sample. The electrochemical tests show that the higher the level of graphite replacement, the higher the level of corrosion in concrete.

Tribological Characteristic of a Ring Seal with Graphite Filler.

This paper presents the outcome of the measurement of the tribological characteristic of O-ring seals in the event of operating in conditions with a lack of lubrication. The measurement was carried out on a seal and rod model. The measurement was carried out during the condition of the round cross-section seal sliding on the surface of the piston rod. We analyzed how the friction force during rod movement, which resulted from the cooperation of the sliding nod and the rod, was changing. The experiment was conducted for various rubber materials. The aim of the research was to evaluate the friction reducing capability of graphite in rubbers of commercial sealing parts. Typical materials used for the seal and the materials, which contained the filler in the form of graphite powder, were compared. Synthetic graphite powder with a particle size of 1–2 µm was applied, and nitrile rubber (NBR) and fluoroelastomer (FKM) were compared as typical materials for O-ring seals. In the case of the two tested materials, the addition of graphite powder had an influence on the decrease in the friction force.

Enhancement of Mechanical Properties in Carbon Fibre Reinforced Epoxy Composite with and without graphite powder

The use of composite material in engineering field is increasing day by day. Composite materials are largely replacing conventional metals nowadays due to their mechanical behaviours. Among all composite materials carbon fibre reinforced composites are of greater interest due to their high strength. There are several new developments made in carbon fibre composites like carbon nanotubes, carbon black etc.. in order to increase the composite strength. In this research, we are going to analyse the strength of the carbon fibre reinforced epoxy composite by using graphite powder as an additive material because of its negligible weight and hardness nature. Generally, composites were prepared by hand layup process. Specifically the tensile, the flexural and the impact properties are taken into the consideration. Three different specimens are prepared and tested for the above strengths. The first specimen is carbon fibre epoxy composite without any addition of graphite powder (filler material). The second one is carbon composite with 5% addition of graphite powder as a filler material and the last specimen is of carbon fibre composite with 10% addition of graphite powder. The above mentioned strengths are calculated for each specimen with the help of a Universal Testing Machine and Impact Tester. Specimen 3 shows greater strengths whereas Specimen 1 shows least strength among all the three specimens. The inclusion of graphite powder in the carbon composite shows increase in the mechanical properties of the resulting specimens.

Synthesis of Sm2Fe17N3 compacts by mechanical milling with graphite powder and their magnetic properties

Abstract It is difficult to prepare Sm 2 Fe 17 N 3 sintered magnets because Sm 2 Fe 17 N 3 phase decomposes above 600°C, and the decomposition results in significant reduction of magnetic properties. To consolidate Sm 2 Fe 17 N 3 powder below the decomposition temperature, an increase of the filling fraction is expected to be one of the effective methods. In this study, an addition of graphite as well as Zn to Sm 2 Fe 17 N 3 powder was conducted by mechanical milling. The dispersion of graphite powder, which acted as a lubricant when compacting the powder, resulted in an increase in the filling fraction. The high relative density, 93.0%, of a sintered body was easily obtained by the addition of the most balanced amounts of graphite and Zn. The magnetization was increased with increase in the additive amount of graphite due to the reduction of the strain accumulated to crystal grains during the mechanical milling. The coercivity was not decreased even when the amount of Zn was reduced, because the Zn powder was dispersed more homogeneously due to the suppression of agglomeration among particles and adhesion of powder to the inside wall of pod during the mechanical milling by the addition of graphite powder.

EFFECT OF GRAPHITE ADDITIVES IN ELECTROLYTES ON CHARACTERISTICS OF MICRO-ARC OXIDATION COATINGS ON 7E04 ALUMINUM ALLOY

Micro-arc oxidation coatings were fabricated on 7E04 aluminum alloy substrates by micro-arc oxidation (MAO) in the electrolytes with the graphite addition varying from 0 to 8[Formula: see text]g/L (0, 2, 4, 6, 8[Formula: see text]g/L). The effect of graphite concentration on the surface morphologies, micro-hardness, thickness, phase composition and corrosion resistance of coatings was investigated. With the graphite powder concentration increasing, the oxidation voltage decreased gradually and the thickness of coatings firstly dropped down and then went up. It is found that the size of micro-pores and sintered discs declined with increase of graphite concentration. The XRD results indicated that MAO coatings mainly consisted of [Formula: see text]-Al2O3, [Formula: see text]-Al2O3, SiO2 and a little [Formula: see text]-Al2O3. The corrosion resistance of coatings was improved with the addition of graphite powder. The study reveals that the appropriate graphite powder in the electrolytes is essential to promote the performance of the coatings.

DETERMINATION OF TECHNOLOGICAL PARAMETERS OF THE AEROSOL TYPE RAIL LUBRICATORS

The article presents the results of experimental studies of technological parameters of a pilot sample of aerosol type lubricant. As a lubricant, the industrial I-12A oil was added with the addition of graphite powder to it, which provides the implementation of a two-layered coating of the working surface of the rail. The test piece is a closed type oiling unit, which feeds on compressed air and allows the regulation of air and oil supply to the working nozzle. For drawing of a lubricant on a working surface the coaxial nozzle with the external formation of an aerosol - a mixture of oils and air is used.Studies were conducted in laboratory conditions. At the first stage, the geometric dimensions of the stain of the oil applied to the vertical surface were measured, depending on the distance between the nozzle and the surface. Such data makes it possible to adjust the settings of the injector placement relative to the rail, taking into account the permissible dimension of the approach, which is essential for the introduction of rail pads under operating conditions. Subsequently, depending on the width of the stain of the oil and the thickness of the lubricating layer from the supply of oil and air, were installed. Also, the dependencies of the cutting time of oil and air are set. The obtained data are necessary for determining the oil consumption in the operation of similar rail lubricants in real conditions. In addition, these data allow you to adjust the control system of the rail lubricant by the criterion of the limit time of cutting the oil and minimizing the cost of lubricant.According to the results of laboratory studies, an estimation of the effectiveness of the aerosol type air-lubricant was performed on the criterion of the total consumption of the lubricant for the predicted resource of the rails in the curved sections of the track. It was obtained the dependence of the number of inclusions of the lubricant and the lubricant flow rate on the number of load cycles for the rails for the projected resource. For one load cycle, a single passage of the wheelset of rolling stock along the rail was taken.

Charge characteristics of adsorbed natural gas storage system based on MAXSORB III

The present work deals with Natural gas (methane) adsorption onto super activated carbon (MAXSORB III) and graphite mixture in order to establish the reliability of this phenomenon as a valuable storage technique of natural gas. The objective of the subject work is to optimize different design and operating parameters of the adsorbed natural gas (ANG) system subjected to variable charge and the boundary conditions. The model duly considers the real gas properties of methane and variation of adsorbed phase properties as well as the heat of adsorption with adsorbate uptake. The storage capacities, storage efficiency as well as the filling time of activated carbon bed are studied for both constant inlet flow and constant inlet pressure charging conditions. The possibility of controlling length to width ratio (L/D ratio ranging from 0.35 to 7.8) is presented which will enable to optimize the geometry of storage tank for optimal storage efficiency. The effects of variation in inlet flow rates and variation in boundary conditions (natural convection, adiabatic wall, forced convection and constant wall temperature) on storage capacity as a function of other design and operating parameters are presented. From the study it is found that for suitable L/D ratio and external heat transfer coefficient it is possible to achieve a storage capacity of 150 V/V for constant pressure charging condition within 200 s. Addition of graphite powder for thermal enhancement of system resulted in 22%–27% (for different L/D ratios) rise in storage efficiency for model subjected to constant pressure charging and forced convection whereas 41.8%–50.4% rise in storage efficiency for model subjected to constant inlet flow and forced convection.

Dielectric Studies of [PEO: CH3COOLi]: Graphite System Synthesized by Hot Press and Solution Cast Technique

Present paper deals with the study of dielectric properties in polyethylene oxide (PEO)—based polymer electrolytes subsequent to dispersal of graphite filler particles synthesized by hot press and solution cast technique. The formation of nanocomposites and changes in the structural and microstructural properties of the materials were investigated by X-ray diffraction, Infrared measurements and optical microscopy. A decrease in crystanillity or increase in amorphousity was found to be more for solution cast film in comparison to hot press film. Electrical and thermal properties of PEO based polymer electrolyte film are found to be enhanced with the addition of graphite powder not only by solution cast method but also by hot press method. The conductivity for film prepared by solution cast method was found be in the range of 10−2 S/cm whereas for film prepared by hot press method the conductivity was found to be in the range of 10−4 S/cm at increasing temperature. The dielectric behavior is analyzed using the dielectric permittivity (e’ and e’’) and tangent loss (tan δ). It is found that the dielectric permittivity (e’ and e’’) rises sharply towards low frequencies and maxima of tangent loss shifts towards higher frequencies for both the films.

Crack Initiation of Alkali-Activated Slag Based Composites with Graphite Filler

The alkali-activated slag is an alternative building material to ordinary Portland cement based materials. This type of material is effective in reducing CO2 emissions and energy consumption. Addition of graphite powder increases its electric conductivity, hence, introducing new functionality to building materials such as self-sensing and self-heating properties. In this study, the effect of graphite filler on the crack initiation of alkali-activated slag composite is investigated. The graphite powder was added in the amount of 5, 10 and 15% with respect to the slag mass. Beam specimens with an initial stress concentrator were tested in three-point bending at the age of 28 days. The load versus crack mouth crack opening displacement (F–CMOD) diagrams were recorded during the fracture tests and subsequently evaluated using the Double-K fracture model. This model allows the quantification of two different levels of crack propagation: initiation, which corresponds to the beginning of stable crack growth, and the level of unstable crack propagation. The course of fracture tests was also monitored by acoustic emission (AE) method.

Microstructure, Hardness and Wear Properties of Sintered Fe-Mo-Si-C Steels with Spheroidal Graphite Iron/Compacted Graphite Iron-Like

Sintered Fe-Mo-Si-C steels were prepared from pre-alloyed Fe-0.85Mo powder added with fixed 4wt.% silicon carbide powder and varied graphite powder contents. It was found that the graphite powder addition caused morphological change from black nodular to black vermicular particles and resulted in decrease of black nodular/vermicular particle fraction, increase of pearlite fraction and slight change of ferrite fraction. The black nodular particles were either graphite or Fe-Mo-Si-C/graphite core-shell particles whereas vermicular particles were totally composed of carbon. The microstructural features showed influence on mechanical property of the sintered Fe-Mo-Si-C alloys. Wear properties of the sintered steels were strongly affected by their microstructural components. The sintered Fe-0.85Mo+4wt.%SiC steels showed highest friction coefficient and volume loss. Addition of graphite to the sintered Fe-0.85Mo+4wt.%SiC steels, not only changed morphology and chemistry of black particles but also reduced friction coefficient and volume loss. The reduction of both determined wear properties were attributed to the presence of vermicular graphite particles.

Performance of Electrical Discharge Milling and Sinking in Micro Graphite Powder Mixed Dielectric

Electrical discharge machining (EDM) is a non-conventional machining technique that is well-known for use in fabricating dies and molds owing to machinability of high hardness materials. Although the electro-thermal mechanism of EDM offers many advantages over other available machining methods, its sluggish nature limits the wide application of such machines for mass production. In this research, adding graphite powder to dielectric is proposed to improve EDM performance factors. Material removal rate (MRR) and average surface roughness (Ra) have been monitored and evaluated after addition of graphite powder to dielectric in electrical discharge milling and sinking. It is found that the presence of powder particles in dielectric fluid enhances the MRR steadily up to ~11 and ~17% for milling and sinking process, respectively. Moreover, the highest enhancement if Ra is ~31% at 1g/l graphite powder concentration for electrical discharge milling and up to ~11% for sinking process. Field emission scanning electron microscopy (FESEM) is used to inspect the machined surfaces. The surfaces machined with graphite powder mixed appear significantly unlike the surfaces machined in pure dielectric. Adding powder to dielectric is found to increase the machined surface hardness by ~26%, from 240 to 302 HV.

Mechanical Fracture Properties of Alkali-Activated Slag with Graphite Filler

Alkali-activated slag is a building material considered as alternative to ordinary Portland cement based materials. Addition of graphite powder increases its electric conductivity, hence, introducing new functionality to building materials such as self-sensing and self-heating properties. In this study, the effect of graphite filler on the mechanical fracture properties of alkali-activated slag composite is investigated. Graphite powder was added in the amount of 5, 10 and 15% with respect to the slag mass. Modulus of elasticity, fracture toughness and fracture energy were determined using standard three-point bending test on prismatic specimens with central edge notch. The course of fracture tests was also monitored by acoustic emission (AE) method. Compressive strength was determined on the fragments remaining after the fracture tests. Results showed that addition of graphite caused a decrease in compressive strength, fracture toughness and fracture energy but modulus of elasticity increased. Addition of graphite also caused a decrease in AE events and increase in amplitude of signals. This implies that mortars with graphite filler is more brittle than the reference mortar, and lower number of much larger cracks is formed during the fracture test.