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To develop high-performance carbon-containing castables, SiC-coated graphite was prepared using Si powder and flake graphite as raw materials by a molten salt isolation method firing at 1 350 °C for 3 h. Then, flake graphite and SiC-coated graphite were introduced into tabular corundum particles, white corundum powder, fused magnesia powder, alumina micropowder, Secar 71 cement, and silica micropowder to prepare Al2O3-MgO castable blank samples and Al2O3-MgO-C castable samples by carbon embedded heat treatment at 1 100 and 1 600 °C. The effect of different graphite types on the properties of the castables was studied. The results show that: (1) compared with the Al2O3-MgO castable sample without graphite, the castable sample with flake graphite has significantly increased water demand for molding, significantly reduced cold modulus of rupture, significantly increased apparent porosity but improved thermal shock resistance and slag resistance; the castable sample with SiC-coated graphite has slightly increased water demand, decreased cold modulus of rupture, slightly increased apparent porosity, and improved hot strength, thermal shock resistance, and slag resistance; (2) with the increase of the heat treatment temperature, the cold strength and permanent linear change rate on heating of the samples increase significantly; (3) when 5 mass % SiC-coated graphite is added and the heat treatment temperature is 1 600 °C, the comprehensive properties of the sample are the best: the cold modulus of rupture is 16.9 MPa, the apparent porosity is 16.0%; the hot modulus of rupture is 2.0 MPa; and the thermal shock resistance and corrosion resistance are good. [ABSTRACT FROM AUTHOR]

The essential part of the flake graphite flotation apparatus is a micro-bubble generator. Developing a micro-bubble generator with a reasonable structure and superior self-absorption performance is crucial to improving flake graphite sorting. In this study, to realize the integrated treatment of the grinding and mineralization of flake graphite, the development and manufacturing of a double-nozzle jet micro-bubble generator were based on the concepts of shear-type cavitation water jets and jet pumps, among other theories. A numerical simulation of the air–water–flake graphite triple-phase flow field of the generator was conducted using the CFD method. The goal was to investigate the grinding and mineralization process of flake graphite by analyzing the distribution of the air phase's volume percentage and the speed distribution of the air–water–flake graphite triple-phase flow field. The findings indicate that the air-phase volume percentage produced by the generator ranges from 98.3% to 99.9%, and the air-phase volume percentage is evenly distributed within the steady flow tube, achieving the mineralization function. Additionally, the flake graphite particles are dissociated from the flake graphite under the combined effect of friction shear and cavitation of the internal nozzles, thereby achieving the grinding function. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies on the implementation of electric arc synthesis of boron carbide using carbon with different morphology and origin as a feedstock: carbon fibers, flake graphite, carbon obtained by pyrolysis of plant waste, namely, pine sawdust and cedar nuts husks. A feature of the electric arc method used is its implementation using an original plasma reactor using atmospheric air as a working gas medium. Oxidation of feedstock and synthesis products in the working cycle of the reactor is prevented due to the generation of CO and CO2 gases in the reaction zone. The possibility of obtaining a material containing micron and submicron boron carbide crystals in a graphite matrix has been experimentally shown. Also, the paper presents information about the features of the oxidation processes of the obtained materials in comparison with commercial samples of boron carbide. [ABSTRACT FROM AUTHOR]

In the mineral processing engineering, ultrasound is usually used to modify reagents to improve the flotation. The study analyses the effects of the modified kerosene on the flotation of flake graphite. The outcomes demonstrate that the modified kerosene can substantially improve flake graphite's floatation efficiency. In comparison to unmodified kerosene, the dosage of modified kerosene can be reduced while the recovery of graphite remains the same. Furthermore, the effect of modified kerosene was evaluated using various detection techniques including particle size distribution measurement, contact angle tests, turbidity tests, and cryo-scanning electron microscopy (Cryo-SEM). The findings indicate that ultrasound modification significantly reduces the size of kerosene to 1–2 μm droplets and improves their dispersion in the aqueous solution. The enhanced dispersion and reduced droplets size of modified kerosene led to a better interaction between kerosene and the surface of flake graphite minerals. As a result, the consumption of kerosene was reduced, but the graphite flotation efficiency was improved. [ABSTRACT FROM AUTHOR]

To investigate the process mineralogy of the flake graphite ore in Heilongjiang province, mineral liberation analyser (MLA) was conducted to systematically study the mineral composition, particle size distribution, and dissemination characteristics of the ore based on the chemical analysis. The results showed that the percentage of the valuable element C existing in the form of graphite is 17.7% and the percentages of the primary gangue minerals feldspar and quartz are 34.32% and 20.83%, respectively. The percentage of large flake graphite whose grain size larger than 0.15mm is 46.17% and the liberation degree of graphite is 70% at 0.18mm. [ABSTRACT FROM AUTHOR]

To improve the microwave deicing efficiency of concrete road, the microwave absorbing agents, including flake graphite and Mn–Zn ferrite, are incorporated into concrete matrix to prepare Graphite Concrete (GC), Ferrite Concrete (FC) and Graphite-Ferrite Concrete (GFC). The indoor-simulated experiments were conducted on a self-designed microwave deicing apparatus. The microwave deicing theoretical feasibility, deicing efficiency and flexural strength were investigated. The agent type, blending method and microwave deicing rate were analyzed. The deicing principle of multiple blending was explored. The results indicate that microwave deicing method for concrete road is feasible and the ice layer near specimen surface melts first under the action of microwave. It is verified that the incorporation of microwave absorbing agent can greatly improve concrete's microwave absorbing and temperature rising performance. In particular, the performance of incorporating graphite is better than ferrite, while the multiple blending is better than single blending. When both graphite and ferrite are added together into concrete matrix, the microwave deicing efficiency can reach 0.61 °C/s, which is 2.79 times that of plain concrete (PC). However, the incorporation of absorbing agent can lead to lowering the flexural strength to some extent. Above all, it can be concluded that the multiple blending of graphite and ferrite has a promising future in improving microwave deicing efficiency of concrete road. [ABSTRACT FROM AUTHOR]

The essential part of the flake graphite flotation apparatus is a micro-bubble generator. Developing a micro-bubble generator with a reasonable structure and superior self-absorption performance is crucial to improving flake graphite sorting. In this study, to realize the integrated treatment of the grinding and mineralization of flake graphite, the development and manufacturing of a double-nozzle jet micro-bubble generator were based on the concepts of shear-type cavitation water jets and jet pumps, among other theories. A numerical simulation of the air–water–flake graphite triple-phase flow field of the generator was conducted using the CFD method. The goal was to investigate the grinding and mineralization process of flake graphite by analyzing the distribution of the air phase’s volume percentage and the speed distribution of the air–water–flake graphite triple-phase flow field. The findings indicate that the air-phase volume percentage produced by the generator ranges from 98.3% to 99.9%, and the air-phase volume percentage is evenly distributed within the steady flow tube, achieving the mineralization function. Additionally, the flake graphite particles are dissociated from the flake graphite under the combined effect of friction shear and cavitation of the internal nozzles, thereby achieving the grinding function.

Graphite Creek is an unusual flake graphite deposit located on the Seward Peninsula, Alaska, USA. We present field observations, uranium-lead (U–Pb) monazite and titanite geochronology, carbon (C) and sulfur (S) stable isotope geochemistry, and graphite Raman spectroscopy data from this deposit that support a new model of flake graphite ore genesis in high-grade metamorphic environments. The Graphite Creek deposit is within the second sillimanite metamorphic zone of the Kigluaik Mountains gneiss dome. Flake graphite, hosted in sillimanite-gneiss and quartz-biotite paragneiss, occurs as disseminations and in sets of very high grade (up to 50 wt.% graphite), semi-massive to massive graphite lenses 0.2 to 1 m wide containing quartz, sillimanite, inclusions of garnet porphyroblasts, K-feldspar, and tourmaline. Restitic garnet, sillimanite, graphite, and biotite accumulations indicate a high degree of anatexis and melt loss. Strong yttrium depletion in monazite, high europium ratios (Eu/Eu*), and excursions of high strontium and thorium concentrations are consistent with biotite dehydration melting. Monazite and titanite U–Pb ages record peak metamorphism from ~ 97 to 92 million years ago (Ma) and a retrograde event at ~ 85 Ma. Raman spectroscopy confirms the presence of carbonaceous material and highly ordered, crystalline graphite. Graphite δ13CVPDB values of − 30 to − 12‰ and pyrrhotite δ34SVCDT values of − 14 to 10‰ are consistent with derivation from organic carbon and sulfur in sedimentary rocks, respectively. These data collectively suggest that formation of massive graphite lenses occurred approximately synchronously with high-temperature metamorphism and anatexis of a highly carbonaceous pelitic protolith. Melt extraction and fluid release associated with anatexis were likely crucial for concentrating graphite. High-temperature, graphitic migmatite sequences within high-strain shear zones may be favorable for the occurrence of high-grade flake graphite deposits. [ABSTRACT FROM AUTHOR]

Flake graphite has excellent explosive electron emission performance for its plenty surface micro-bulges and high graphitization degree, but its advantages have rarely been studied in relativistic magnetrons. In this paper, flake graphite cathodes with different fineness were used in coaxial diodes and relativistic magnetrons, and the influence of the surface microstructure of the flake graphite cathode on the relativistic magnetron performance is demonstrated for the first time. The result showed that the graphite microstructure mainly affected the initiation stage of explosive emission. Moreover, the delay time is determined by the degree of graphitization and the surface microstructure of graphite, and the surface microstructure plays a major role. Under the applied voltage of ~330kV-~490kV, The finer flake graphite possessed a shorter emission delay and facilitated the microwave excitation. The excitation time of finer flake graphite is $\sim 3ns$ , and $\sim 5ns$ for lager flake graphite. After several operations of the relativistic magnetron, the edges of flake graphite were blunted, and the surface of the flake graphite appeared droplet-like areas formed by anode atom sputtering. This work reveals the advantages of the finer flake graphite cathode in the fast priming of the relativistic magnetron, thus shedding new light on cathode design of the relativistic magnetron.

Aqueous zinc batteries with low cost and inherent safety are considered to be the most promising energy storage devices. V2O5/Flake graphite material have been successfully synthesized via high-temperature magnetic stirring and sintering method. V2O5/Flake graphite material were characterized by X-ray diffraction, FESEM, XPS and TGA. The addition of flake graphite not only improves the conductivity of the cathode material, provides more active sites for the Zn2+ insertion/extraction process, but also has a certain isolation effect, avoiding the direct contact between the electrolyte and the V2O5 to cause dissolution. VC51 delivers a high discharge capacity of 328.1 mA h g–1 at 0.1 A g–1, good capacity retention of 81.4% after 300 cycles, shows good cycling stability. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Viscosity shifts the flow features of a liquid and affects the consistency of a product, which is a primary factor in demonstrating forces that should be overcome when fluids are transported in pipelines or employed in lubrication. In carbon-based materials, due to their extensive use in industry, finding the simple and reliable equations that can predict the rheological behavior is essential. In this research, the rheological nature of graphene/aqueous nanofluid was examined. Fourier transform infrared spectroscopy, dynamic light scattering, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction were used for analyzing the phase and structure. Transmission electron microscopy and field emission scanning electron microscopy were also employed for micro and nano structural-study. Moreover, nanofluid stability was examined via zeta-potential measurement. Results showed that nanofluid has non-Newtonian nature, the same as the power-law form. Further, from 25 to 50°C, at 12.23 s−1, viscosity decreased by 56.9, 54.9, and 38.5% for 1.0, 2.0, and 3.5 mg/mL nanofluids, respectively. From 25 to 50°C, at 122.3 s−1, viscosity decreased by 42.5, 42.3, and 33.3% for 1.0, 2.0, and 3.5 mg/mL nanofluids, respectively. Besides, to determine the viscosity of nanofluid in varied temperatures and mass concentrations, an artificial neural network via R 2 = 0.999 was applied. Finally, the simple and reliable equations that can predict the rheological behavior of graphene/water nanofluid are calculated.

In the desulfurization process of molten iron, the supersaturated carbon dissolved in molten iron precipitates in the form of graphite. In this paper, according to the characteristics of graphite contained in molten iron desulfurization slag, the flotation method was firstly used to recover the graphite with kerosene used as collector and No.2 oil used as foaming agent, and then the ball milling and magnetic separation process was used to physically remove the impurities of the recovered graphite, and finally the hydrochloric acid and hydrofluoric acid were used for chemically purification. With the result, high purity flake graphite was prepared. The results show that the graphite recovery firstly increases and then decreases with the increase of flotation agent dosage. When the total dosage of kerosene and No.2 oil is 1200 g/t and w (kerosene: No.2 oil) = 4:1, the recovery is more than 97%. The ball milling treatment separated the impurities from the graphite surface, while the magnetic separation reduced iron content in graphite. After three times of the ball milling and magnetic separation treatment, the fixed carbon content in graphite increases from 58% to more than 88%. Under the optimum conditions, the ash content of graphite can be reduced to 0.03% by mixed acid treatment, reaching the standard of high purity graphite. SEM analysis also showed no significant difference in shape between the recovered flake graphite and the natural flake graphite.

Improvement in volumetric performance is growing requirements for rechargeable batteries of lightweight and compact size. Flake graphite (FG) with thin lamellar structure realizes a satisfactory K‐ion storage performance, but its low packing density leads to poor volumetric capacity. Herein, this work fabricates an FG anode with improved packing density by hydrothermal treatment of the FG with graphene oxide and subsequent capillary evaporation‐induced drying process. A three‐dimensional flake graphite/reduced graphene oxide (FG/rGO) hydrogel is formed after hydrothermal treatment, which can be compressed during drying process via the capillary force generated by water evaporation, resulting in a compact structure with enhanced packing density. Compared to the pristine FG electrode (106.0 mAh cm−3), the FG/rGO‐82 anode realizes an ultrahigh volumetric capacity of 218.9 mAh cm−3 and good rate performance with a retained capacity of 152.3 mAh cm−3 at 2 C. Moreover, the FG/rGO‐82 exhibits excellent cycle stability with a capacity retention of 90.1% after 300 cycles. Even under a high mass loading of 7.4 mg cm−2, it still remains a volumetric capacity of 145.4 mAh cm−3 after 300 cycles at 1 C. The results prove that the capillary evaporation induced drying of hydrogel is an effective way to prepare electrode material with high volumetric capacity. [ABSTRACT FROM AUTHOR]

Abstract Improvement in volumetric performance is growing requirements for rechargeable batteries of lightweight and compact size. Flake graphite (FG) with thin lamellar structure realizes a satisfactory K‐ion storage performance, but its low packing density leads to poor volumetric capacity. Herein, this work fabricates an FG anode with improved packing density by hydrothermal treatment of the FG with graphene oxide and subsequent capillary evaporation‐induced drying process. A three‐dimensional flake graphite/reduced graphene oxide (FG/rGO) hydrogel is formed after hydrothermal treatment, which can be compressed during drying process via the capillary force generated by water evaporation, resulting in a compact structure with enhanced packing density. Compared to the pristine FG electrode (106.0 mAh cm−3), the FG/rGO‐82 anode realizes an ultrahigh volumetric capacity of 218.9 mAh cm−3 and good rate performance with a retained capacity of 152.3 mAh cm−3 at 2 C. Moreover, the FG/rGO‐82 exhibits excellent cycle stability with a capacity retention of 90.1% after 300 cycles. Even under a high mass loading of 7.4 mg cm−2, it still remains a volumetric capacity of 145.4 mAh cm−3 after 300 cycles at 1 C. The results prove that the capillary evaporation induced drying of hydrogel is an effective way to prepare electrode material with high volumetric capacity.

Flotation is one of the most used methods to upgrade natural graphite resources. However, the efficiency is usually decreased due to the entrainment of undesirable fine gangue minerals. In this work, the impact of different factors such as particle size, pulp density, and flotation reagent on the entrainment of mica and quartz in a flake graphite flotation was studied. The single gangue mineral flotation results showed increased gangue entrainment when reducing the particle size of gangue minerals and increasing the pulp density. Moreover, the flotation of artificial mixtures indicated enhanced entrainment of mica and quartz in the presence of graphite particles. The collector and frother also strongly affect gangue entrainment by modifying the structure and stability of the froth. Kerosene, which has a prominent deforming feature, can reduce gangue entrainment more effectively than diesel. [ABSTRACT FROM AUTHOR]

Natural flake graphite has wide application in carbon containing refractories owing to its low density, high thermal conductivity, low thermal expansion coefficient, and good thermal shock resistance and slag corrosion resistance. However, graphite has some disadvantages such as poor hydrophilicity and easy oxidation at high temperatures, which limits its application in refractories. Surface coating of graphite is an effective method to overcome the disadvantages. The research progress of graphite surface modification methods in recent years was reviewed, their advantages and disadvantages were analyzed, and the development direction was prospected. [ABSTRACT FROM AUTHOR]

Flake graphite cast iron has high damping capacity. Among the various theories on the damping mechanism of cast iron, the viscoelastic layer between matrix and graphite is an important factor. This indicates that the increase in surface area and quantity of graphite would be effective for improving the damping capacity of the cast iron. In this research, aluminum, which is a graphitizing element, was added to the flake graphite cast iron. The concentration of aluminum in the cast iron specimens was controlled from 0 to 7 mass%. The graphite and matrix structure were examined by optical microscopy and FE-EPMA, and the perimeter and area ratio of graphite in the cast irons and the damping capacity were measured. Addition of aluminum up to 5 mass% increased the area ratio and surface area of flake graphite in the cast irons. Addition of 3 ~ 5 mass% aluminum improved the damping capacity of the flake graphite cast irons, and that of 5 mass% aluminum cast iron was twice as compared with that of the cast iron without aluminum. This was attributed to the increase in the amount of graphite due to the addition of aluminum and to the refinement of the graphite, which contributed to the increase in the graphite surface area. Although the damping capacity of 7 mass% aluminum cast iron was smaller than that of 5 mass% aluminum one, it was higher than the cast iron specimens with the similar area ratio and surface area of flake graphite. This indicates that the κ phase observed in the as-cast high aluminum specimens and aluminum dissolved in the matrix of the heat-treated high aluminum cast iron specimens would have some effect for improving the damping capacity. The damping capacity at every temperature was decreased due to a heat-treatment in a condition, which decomposed the graphite.

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Flake graphite @polyimide (FG@PI) particles with core @shell like structure were successfully synthesized and subsequently incorporated into PI matrix to prepare p I/FG@PI composite films. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed that flake graphite (FG) was covered by PI coating and showed a fluffy structure. Thermogravimetric analysis (TGA), FT-IR, and XRD were also used to characterize FG@PI particles. The PI intermediate layer increases interaction between particles and films, which is very beneficial for increasing dielectric constant and inhibiting dielectric loss of p I/FG@PI composite. The experimental result shows that the p I/FG@PI composite film with 50wt% filler loading exhibits a high dielectric constant of 83.5 (about 24 times that of pure PI) and low dielectric loss of 0.11 at 1 MHz. Furthermore, its tensile strength is maintained at 78 MPa. This shows that the structure of PI intermediate layer is very beneficial for preparation of high dielectric constant and low dielectric loss composite. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Flotation is one of the most common and effective methods for the beneficiation of natural graphite resources. However, the upgrading efficiency of flotation is always finite due to the undesirable collection of gangue minerals. In this work, the collecting mechanism of three typical gangue minerals, including mica, quartz, and feldspar, in fine flake graphite flotation was investigated. Results of batch flotation tests for single-minerals and artificial mixtures confirmed the enhanced collection of gangues in the presence of graphite particles. Contact angle and zeta potential results and theoretical calculations of the interaction between graphite and gangue particles based on typical DLVO theory indicated that it is impossible to collect gangue minerals by true flotation or through heterocoagulation with graphite particles. The fitting results of accumulated gangue recoveries and accumulated water recoveries using the Warren method demonstrated that most gangue minerals entered the concentrate through entrainment, with a small proportion by bubble inclusions. [ABSTRACT FROM AUTHOR]

The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections. Herein, for estimating the carbon content in graphite, the ASTM-C561, the test method for ash in a graphite sample, was used. For characterizing graphite, x-ray diffraction, x-ray fluorescence, inductively coupled plasma mass spectroscopy, and scanning electron microscopy were also used. Chemical analysis of ore samples determined that the average compositions are 63.35% SiO2, 15.45% Al2O3, 2.36% Fe2O3, 2.07% K2O, less than1% others, and loss-on-ignition (LOI) in the range of ~4.74%–37.42%. The total carbon content of graphitic ore ranged from 4.11% to 33.14%. Importantly, when graphite is concentrated through floatation, its average purity and recovery are 92.97% and 90.82%, respectively. Furthermore, once the graphite concentrates are treated with hydrofluoric acid, the average value attains a high grade of 96.48% C. Moreover, the average ash content is 81.93% (pre-flotation) and 3.1% (post-flotation), respectively. Finally, after beneficiation, a silica is identified as a major gangue (85.88%), usable as a raw material for other purposes such as cement. Hence, these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.

A new theoretical model of gray cast iron taking into account a locally interconnected structure of flake graphite was designed, and the corresponding effective thermal conductivity was calculated using the thermal resistance network method. The calculated results are obviously higher than that of the effective medium approximation assuming that graphite is distributed in isolation. It is suggested that the interconnected structure significantly enhances the overall thermal conductivity. Moreover, it is shown that high anisotropy of graphite thermal conductivity, high volume fraction of graphite, and small aspect ratio of flake graphite will cause the connectivity effects of graphite to more obviously improve the overall thermal conductivity. Higher graphite volume fraction, lower aspect ratio and higher matrix thermal conductivity are beneficial to obtain a high thermal conductivity gray cast iron. This work can provide guidance and reference for the development of high thermal conductivity gray cast iron and the design of high thermal conductivity composites with similar locally interconnected structures.

The properties of gray cast iron (GCI) are affected by density of matrix, size of flake graphite and primary austenite. In this paper, the Y-type specimen of GCI was prepared by lost foam casting (LFC) with and without vibration, and the influence of vibration frequency on the density of matrix, size of primary phase, and properties of the GCI was studied. The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency. With a vibration frequency of 35 Hz, the length of the flake graphite is the shortest, the primary austenite is the finest and the density of the matrix is the highest. In addition, the tensile strength, elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency, due to the refinement of the primary phase and the increase of the matrix density. In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration, the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured. The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation. As a result, the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.

PP/FG composite materials were prepared by compressing moulding under high temperature through high-speed mixer, mixing mill and vulcanization machine taking PP as the matrix resin, FG as the thermal conductive filler, and NDZ-201 as the coupling agent. Effects of PP proportion, FG content and particle size on the thermal conductivity and mechanical properties of composite materials were studied. Results showed that PP proportion has little effect on the thermal conductivity of PP/FG composite materials, but it greatly affects the mechanical properties of the composite materials. Overall, the quality ratio of PP230 to K-4038 at 50:50 is more suitable. With the increasing of FG content, the thermal conductivity increases, and a significant critical value appears when the FG content is 50 wt%; The strength of the composite material first decreases and then increases, with an increase in modulus and a decrease in strain. As the FG particle size increases, the thermal conductivity of the composite material increases and the mechanical properties decrease.

Copyright of Journal of Heilongjiang University of Science & Technology is the property of Journal of Heilongjiang University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herein, we investigated the genesis of Toungo flake graphites in the basement complex of Adamawa Massif, northeastern Nigeria, and evaluated their industrial quality. Field and laboratory evidences show that the foliated amphibolite and gneisses are the main rock unit hosting the graphite and are occasionally bordered by pegmatite. Petrographic data show that graphites in Mayo Butale (MB) and Walon Kole (WK) are associated with chlorite, suggesting a role of CO2-bearing aqueous fluids in the origin of the large and minor graphite flakes under regional greenschist facies conditions. The hydration processes related to the formation of chlorite drove the fluid composition toward CO2 saturation and graphite precipitation. The close association of the graphite with pegmatites shows that graphite precipitation occurs synchronously with melt crystallization during cooling, suggesting that C-bearing fluids exsolved from the parent melts of pegmatites. The flake sizes of Walon Kole (WK) and Mayo Butale (MB) graphites range between ~0.2 and 0.6 mm, reflective of high-quality flakes. Their light bulk densities (WK = 2.38 g/cm3; MB = 2.29 g/cm3) make them less susceptible to crushing and cracking, while their porosities (WK = 3.25–5.26%; MB = 1.4–6.88%) are suitable for use in refractory industries. Given their low moisture contents (WK = 0.27%; MB = 0.16%) and volatile matter (WK = 2.1%; MB = 4.90%), the graphites can be used to produce silicon carbides, fire-retardant additives, as well as refractory bricks, lubricants, automobile brakes, clutches, and pencil lead. Their ash contents (WK = 15%; MB = 18%) and compressive strengths (WK = 23 N/mm2; MB = 16.5 N/mm2) connote mechanical strength and good workability, thus suitable for producing crucibles, coatings of TV tube, and conductive concrete used in making cement. The graphite's thermal shock resistance is satisfactory for use in refractory industries as it withstood severe cycles of heating. Taken together, the quality of Toungo graphites conform to the minimum industrial quality standards but can be beneficiated to meet the optimum industrial grades. [ABSTRACT FROM AUTHOR]

With the miniaturization of electronic components and the complication of packaging processes, operating environments with high power density are bound to generate large amounts of heat. Conventional thermal interface material (TIM) typically aims to enhance thermal conductivity (TC) in only one direction (either through-plane or in-plane), which is insufficient to meet the growing requirement for heat dissipation. Here, highly oriented and tightly fitted flake graphite (FG)-based TIM with dual-direction thermal conductive pathways were prepared via rotating magnetic field assisted casting (RMAC), which can dissipate heat quickly in both directions. The results revealed that at 50 wt% filler and 30 r/min magnetic field rotation rate, the composites with dual-direction thermal conductive pathways exhibited in-plane and through-plane TC of 12.8 and 10.1 W/mK, respectively. Notably, these values represent significant improvements of 415.4 % and 134.1 % over random composites and also demonstrate outstanding advantages over composites with filler orientation in only one direction, horizontal or vertical. This also has been confirmed by finite element simulations and actual thermal characterization. The rational structural design of the filler in TIM can efficiently direct heat away from specific directions, which provides a feasible solution to the heat dissipation problem of high-power-density electronic devices. [Display omitted] • Dual-direction thermal conductive FG-based composites were prepared via RMACand a two-step curing method. • The through-plane and in-plane TC of D-50 are 10.1 and 12.8 W/mK, respectively, which are 4.2 and 1.3 times higher than R-50. • The effect of the magnetic field's rotational speed on the filler's orientation angle and through-plane TC was investigated. [ABSTRACT FROM AUTHOR]

The high concentration graphene aqueous dispersion was obtained by high-pressure homogenization liquid phase exfoliation (HPH-LPE) of flake graphite in water. The effect of surfactant concentration, HPH pressure and cycle number on the concentration of graphene dispersion CG was studied by UV-Vis spectra. The structure and morphology of graphene were analyzed by Roman spectra, SEM and TEM. The results indicate that CG is obtained up to 324.3mg·L-1 for the first time by the parameters optimization, which is 10 times higher than that obtained by sonication; graphene obtained has few defects, thin thickness and large size, indicating the good quality of graphene production; the conductivity of free-standing film prepared by the obtained graphene dispersion can reach 3.2×104S·m-1.

Flotation is one of the most used methods to upgrade natural graphite resources. However, the efficiency is usually decreased due to the entrainment of undesirable fine gangue minerals. In this work, the impact of different factors such as particle size, pulp density, and flotation reagent on the entrainment of mica and quartz in a flake graphite flotation was studied. The single gangue mineral flotation results showed increased gangue entrainment when reducing the particle size of gangue minerals and increasing the pulp density. Moreover, the flotation of artificial mixtures indicated enhanced entrainment of mica and quartz in the presence of graphite particles. The collector and frother also strongly affect gangue entrainment by modifying the structure and stability of the froth. Kerosene, which has a prominent deforming feature, can reduce gangue entrainment more effectively than diesel.

Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years; this is due to the ultra-stable cycling, high capacity, and good safety of the systems. This study discussed the change of electrochemical behaviors caused by the structural difference between flake graphite and expandable graphite, the effects of temperature on the electrochemical performance of graphite in low-cost AlCl3–NaCl inorganic molten salt, and the reaction mechanisms of aluminum complex ions in both graphite materials by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, cyclic voltammetry, and galvanostatic charge–discharge measurements. It was found that flake graphite stacked with noticeably small and thin graphene nanosheets exhibited high capacity and fairly good rate capability. The battery could achieve a high capacity of ∼219 mA hg−1 over 1200 cycles at a high current density of 5 Ag−1, with Coulombic efficiency of 94.1%. Moreover, the reaction mechanisms are clarified: For the flake graphite with small and thin graphene nanosheets and high mesopore structures, the reaction mechanism consisted of not only the intercalation of AlCl 4 − anions between graphene layers but also the adsorption of AlCl 4 − anions within mesopores; however, for the well-stacked and highly parallel layered large-size expandable graphite, the reaction mechanism mainly involved the intercalation of AlCl 4 − anions. [ABSTRACT FROM AUTHOR]

The surface modified flake graphite (FG) was filled into polypropylene (PP) and mixed by a double-roll open mill. FG/PP composites with high thermal conductivity were prepared by compression molding. Studies had shown that the modification of FG by coupling agent was beneficial to the dispersion in FG/PP composites. The effect was better when the amount of NDZ-201 was 0.7wt%. With the increase of FG particle size, the thermal conductivity of FG/PP composites increased obviously. Compared with 17μm FG, the average, vertical and parallel thermal conductivity of FG/PP composites prepared with 148μm FG increased by 65.9%, 87.7% and 47.0% respectively. The thermal conductivity of FG/PP composites were improved with the increase of FG content. When FG content was 70wt%, the thermal conductivity increased significantly, the average, vertical and parallel thermal conductivity reached 4.16 W·m-1·K-1, 0.938 W·m-1·K-1 and 18.4 W·m-1·K-1.

The flake graphite occurrence in Piippumäki, Eastern Finland, as indicated by an airborne electromagnetic anomaly, was located during fieldwork by electromagnetic measurements with Slingram. The anomaly is approximately 0.1 × 1 km in size. The flake graphite is hosted by quartz-feldspar gneiss and amphibolite that have been subjected to retrograde metamorphism. This is observed in thin sections as granulite facies (garnet + cordierite + sillimanite + melt) regressing to greenschist facies (epidote, chlorite, albite, and white mica). The graphite (up to 1 mm large flakes) is found in graphite-bearing layers in the gneiss, and to a minor extent disseminated in the amphibolite. The average total sulfur (TS) is 0.33%, total carbon (TC) is 6.49%, and the average content of graphitic carbon (Cg) is 6.41% for the analyzed graphite-bearing rocks. SEM, XRD, and Raman spectroscopy were used for analyzing the flake graphite, indicating that the graphite is almost defect-free, of high quality, and has not been affected by the retrograde metamorphism. The peak metamorphic temperature of 737 °C was determined by a Raman thermometer, and no temperatures of greenschist facies were observed. A pseudosection was constructed from whole-rock chemical composition and indicated equilibration at ca 5 kbar and 740 °C, which corresponds to the observed mineral assemblages. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploration of effective electromagnetic wave absorption (EWA) materials is still urgent in terms of the electromagnetic wave pollution and radiation. Herein, the thin-layered flake graphite prepared by shear-assisted supercritical CO 2 exfoliation possesses excellent absorption property over the frequency range of 2–18 GHz, with broad effective absorption peaks at 4–8 GHz and 10–18 GHz where the value of reflection loss (RL) is below −30 dB and the RL min of −49 dB at a thickness of 1.49 mm with only 20 wt% loading. The thin-layered flake graphite with large size (average 179.9 μm) possesses high conductivity, contributing to a large number of electronics migrating. However, the graphite with small size distribution is favorable to dipole polarization and interfacial polarization. As the small size graphite sheets (25 wt%) were distributed among the gaps between the large flake graphite sheets (75 wt%), the enhanced electronics migrating bridge effect between the large flake graphite sheets would be available for the enhanced dielectric loss. Our study paves an effective way for scalable and green production of high efficient EWA materials. The thin-layered flake graphite with suitable transverse size distribution was exfoliated by shear-assisted supercritical CO 2 fluid, which has excellent microwave absorption performance. Image 1 [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)