Articles de revues : « Graphite Technique »

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Yürüm, Yuda, Burcu Saner Okan, Firuze Okyay, Alp Yürüm, Fatma Dinç, Neylan Görgülü et Selmiye Alkan Gürsel. « An Improved Technique for the Exfoliation of Graphene Nanosheets and Utilization of their Nanocomposites as Fuel Cell Electrodes ». Key Engineering Materials 543 (mars 2013) : 9–12. http://dx.doi.org/10.4028/www.scientific.net/kem.543.9.

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Graphene is a flat monolayer of carbon atoms tightly packed into a two-dimensional 2D honeycomb lattice. The graphene sheets in graphite interact with each other through van der Waals forces to form layered structure. The first graphene sheets were obtained by extracting monolayer sheets from the three-dimensional graphite using a technique called micromechanical cleavage in 2004 [. There are numerous attempts in the literature to produce monolayer graphene sheets by the treatment of graphite. The first work was conducted by Brodie in 1859 and GO was prepared by repeated treatment of Ceylon graphite with an oxidation mixture consisting of potassium chlorate and fuming nitric acid [. Then, in 1898, Staudenmaier produced graphite oxide (GO) by the oxidation of graphite in concentrated sulfuric acid and nitric acid with potassium chlorate [. However, this method was time consuming and hazardous. Hummers and Offeman found a rapid and safer method for the preparation of GO and in this method graphite was oxidized in water free mixture of sulfuric acid, sodium nitrate and potassium permanganate [.

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Misra, Shikhar, Nirmal Kumar Katiyar, Arvind Kumar, Saurav Goel et Krishanu Biswas. « Nanofabrication route to achieve sustainable production of next generation defect-free graphene : analysis and characterisation ». Nanofabrication 6, n^o 1 (1 janvier 2021) : 36–43. http://dx.doi.org/10.1515/nanofab-2020-0101.

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Abstract In the past two decades, graphene has been one of the most studied materials due to its exceptional properties. The scalable route to cost-effective manufacture defect-free graphene has continued to remain a technical challenge. Intrinsically defect-free graphene changes its properties dramatically, and it is a challenging task to control the defects in graphene production using scaled-down subtractive manufacturing techniques. In this work, the exfoliation of graphite was investigated as a sustainable low-cost graphene manufacturing technique. The study made use of a simple domestic appliance e.g., a kitchen blender to churn graphene in wet conditions by mixing with N-Methyl-2-pyrrolidone (NMP). It was found that the centrifugal force-induced turbulent flow caused by the rotating blades exfoliates graphite flakes to form graphene. The technique is endowed with a high yield of defect-free graphene (0.3 g/h) and was deemed suitable to remove 10% fluoride content from the water and color absorption from fizzy drinks.

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Ishikawa, Makoto, Shu Kamiya, Shoji Yoshimoto, Masaru Suzuki, Daisuke Kuwahara, Naruo Sasaki et Kouji Miura. « Nanocomposite Materials of Alternately StackedC60Monolayer and Graphene ». Journal of Nanomaterials 2010 (2010) : 1–6. http://dx.doi.org/10.1155/2010/891514.

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We synthesized the novel nanocomposite consisting alternately of a stacked single graphene sheet and aC60monolayer by using the graphite intercalation technique in which alkylamine molecules help intercalate largeC60molecules into the graphite. Moreover, it is found that the intercalatedC60molecules can rotate in between single graphene sheets by usingC13NMR measurements. This preparation method provides a general way for intercalating huge fullerene molecules into graphite, which will lead to promising materials with novel mechanical, physical, and electrical properties.

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Okan, Burcu Saner, Selmiye Alkan Gürsel et Yuda Yürüm. « Surface Modifications of Graphene-based Polymer Nanocomposites by Different Synthesis Techniques ». MRS Proceedings 1451 (2012) : 131–36. http://dx.doi.org/10.1557/opl.2012.1455.

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ABSTRACTWith the appropriate surface treatments, graphene sheets can be separated from graphite material and the layer-to-layer distance can be extended. In the present work, graphene nanosheets (GNS) were separated from graphite by an improved, safer and mild method including the steps of oxidation, thermal expansion, ultrasonic treatment and chemical reduction. For the production of advanced polymer nanocomposites, the distinguished properties of GNS were combined with the structural properties of conducting polypyrrole by the proposed simple and low-cost fabrication technique. The changes in surface morphologies and surface functional groups were estimated by controlling the polymer coating on graphite oxide (GO) sheets, expanded GO and GNS.

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Saranya, K., N. Sivasankar et A. Subramania. « Microwave-assisted exfoliation method to develop platinum-decorated graphene nanosheets as a low cost counter electrode for dye-sensitized solar cells ». RSC Adv. 4, n^o 68 (2014) : 36226–33. http://dx.doi.org/10.1039/c4ra05044d.

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Ilnicka, Anna, Malgorzata Skorupska, Piotr Kamedulski et Jerzy P. Lukaszewicz. « Electro-Exfoliation of Graphite to Graphene in an Aqueous Solution of Inorganic Salt and the Stabilization of Its Sponge Structure with Poly(Furfuryl Alcohol) ». Nanomaterials 9, n^o 7 (3 juillet 2019) : 971. http://dx.doi.org/10.3390/nano9070971.

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We demonstrate an accessible and effective technique for exfoliating graphite foil and graphite powder into graphene in a water solution of inorganic salt. In our research, we report an electrochemical cathodic exfoliation in an aqueous solution of Na2SO4. After electro-exfoliation, the resulting graphene was premixed with furfuryl alcohol (FA) and an inorganic template (CaCO3 and Na2CO3). Once FA was polymerized to poly(furfuryl alcohol) (PFA), the mixture was carbonized. Carbon bridges originating in thermally-decomposed PFA joined exfoliated graphene flakes and stabilized the whole sponge-type structure after the nano-template was removed. Gases evolved at the graphite electrode (cathode) played an important role in the process of graphene-flake splitting and accelerated the change of graphite into graphene flakes. Starting graphite materials and graphene sponges were characterized using Raman spectroscopy, SEM, high-resolution transmission electron microscopy (HRTEM), elemental analysis, and low-temperature adsorption of nitrogen to determine their structure, morphology, and chemical composition. The discovered manufacturing protocol had a positive influence on the specific surface area and porosity of the sponges. The SEM and HRTEM studies confirmed a high separation degree of graphite and different agglomeration pathways. Raman spectra were analyzed with particular focus on the intensities of ID and IG peaks; the graphene-type nature of the sponges was confirmed.

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Aguilera Mandujano, A., et J. Serrato Rodriguez. « Synthesis and characterization of titania/graphene nanocomposite for application in photocatalysis ». Revista Mexicana de Física 66, n^o 5 Sept-Oct (1 septembre 2020) : 610. http://dx.doi.org/10.31349/revmexfis.66.610.

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Titanium dioxide has been extensively investigated as a photocatalyst for water purification, presenting limitations such as recombination of electron-hole pairs generated by photons. The titania / graphene nanocomposites are promising materials to overcome these limitations due to the high specific area of graphene and unique electronic properties. In this work, an anatase-graphene nanocomposite was synthesized by a simple mixture assisted by ultrasound. Graphene was obtained by electrochemical exfoliation of graphite using the electrolysis technique. On the other hand, anatase was synthesized using the sol gel method. The obtained graphene, anatase and the nanocomposite material, were characterized with the X-ray diffraction technique (DRX), scanning electron microscopy (MEB) and transmission electron microscopy (MET). Using Raman spectroscopy, it was possible to verify that the graphite exfoliated correctly producing few layer-graphene. The lamellar nano-structure of the exfoliated graphite has crystallographic planes characteristic of graphite, graphene and graphene oxide. The presence of the anatase phase is shown in the diffraction spectrum of titania. The images obtained with SEM and TEM of the graphene sample show a layered lamellar structure and the TiO2 images show agglomerates of ellipsoidal nanoparticles. Obtained titania nanoparticles have a size of about 6 nm. Band gap value for such extremely low particle size nanocomposite is around 3.6 eV and presumably corresponds to the TiO2 (anatase) phase that completely surrounds the graphene. A nanocomposite model based on HRTEM observations is proposed. Considering the graphene electrical properties and the photocatalytic properties of TiO2, this nanocomposite promises to have applications in photocatalysis.

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Patil, Rohan, Manisha Phadatare, Jonas Örtegren, Magnus Hummelgård, Nicklas Blomquist, Håkan Olin, Santosh Limaye et al. « A Scalable Furnace Technique to Grow Silicon Nanoparticles for High-Performance Li-Ion Battery Anodes ». ECS Meeting Abstracts MA2023-02, n^o 2 (22 décembre 2023) : 425. http://dx.doi.org/10.1149/ma2023-022425mtgabs.

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Lithium-ion battery (LIB) technology is one of the key technologies to lower the emission from fossil fuel while maintaining stable supply of energy to the society. One way to increase the capacity of LIBs is to add silicon to the graphite anode, since silicon can store much more lithium ions than graphite. Silicon does however expand and contract during lithiation and delithiation, leading to cracks which deteriorates the performance of the LIB anode. Mechanical cracking can be avoided by using sufficiently small silicon nanoparticles. Several high-performance schemes utilizing silicon nano materials such as nanoparticles, nanotubes, nanorods etc. have been demonstrated but industrial-scale implementation of these solutions still poses a challenge. The Siemens process is one of the most commonly used methods to create silicon nanoparticles and uses chemical vapor deposition (CVD) processes involving silane or silane derivatives as precursors. Due to the flammable and toxic nature of silane, the CVD process requires special handling care and expensive instrumentation. In this work, a novel scalable furnace technique to create silicon nanoparticles attached to graphene flakes LIB anode applications is presented. With this technique, we can avoid the silane precursor. In addition, the instrumentation requirements of the furnace technique are quite simple and inexpensive and the technology is compatible with already established industrial-scale electrode manufacturing techniques. In the work presented here we demonstrate how silicon nanoparticles are grown from micro sized silicon powder onto graphene flakes using simple thermal treatment. Thermal gravitometry, mass spectrometry and differential scanning calorimetry was used to show how silicon powder and a binder can be converted to silicon nanoparticles by simple pyrolysis. The silicon nanoparticles are grown on top of graphene flakes to create a LIB anode. The anode, when tested in a half cell assembly shows a capacity that is considerably higher than standard graphene/graphite electrodes.

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Chaban, Vitaly V., et Eudes Eterno Fileti. « Graphene exfoliation in ionic liquids : unified methodology ». RSC Advances 5, n^o 99 (2015) : 81229–34. http://dx.doi.org/10.1039/c5ra16857k.

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Rubanik, V. V., V. O. Savitsky, V. V. jr Rubanik, V. F. Lutsko, I. V. Nikiforova, Hung Thang Bui et Dinh Phuong Doan. « OBTAINING GRAPHENE STRUCTURES AND NANOPOLYMERS USING ULTRASONIC VIBRATIONS ». Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta, n^o 3 (2021) : 74–83. http://dx.doi.org/10.18323/2073-5073-2021-3-74-83.

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Graphene-based polymer nanocomposites are considered a promising class of future materials. The degree of filling, the filler and binder nature, and the shape, size, and mutual arrangement of filler particles determine the properties of a polymer composite material. The destruction of nanoparticles aggregates occurs most effectively in liquid media under the action of ultrasonic vibrations. The authors proposed the technique and designed laboratory equipment for ultrasonic treatment of the finely-dispersed graphite suspension, carried out the ultrasonic treatment (UST) of finely-dispersed graphite powder. The suspensions based on graphite with a solvent were obtained. The authors carried out the experiments on producing graphene using the graphite liquid-phase exfoliation method at the ultrasonic treatment with different ultrasonic treatment times, analyzed experimental data, and selected the UST optimal time. The paper contains the results of the study of the effect of the graphite suspension base on the degree of ultrasonic liquid-phase exfoliation of graphite. The most effective synthesis of graphene structures using UST is synthesis from graphite suspensions based on dichloroethane, benzol, and dichlorobenzene. Graphene structures’ output ratio amounts to up to 66 %. The authors developed the technology for producing polymers modified with graphene structures using ultrasonic dispersion. Based on graphene synthesized by the graphite liquid-phase exfoliation, the authors obtained nanopolymers using ultrasonic vibrations, carried out DSC measurements, and studied their strength properties. The limit strength of elastic polymers is from 1.9 to 3.6 MPa at different concentrations of graphene inclusions. The residual elongation of samples within the deviation did not change and amounted to 200 %.

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Rubanik, V. V., V. O. Savitsky, V. V. jr Rubanik, V. F. Lutsko, I. V. Nikiforova, Hung Thang Bui et Dinh Phuong Doan. « OBTAINING GRAPHENE STRUCTURES AND NANOPOLYMERS USING ULTRASONIC VIBRATIONS ». Vektor nauki Tol'yattinskogo gosudarstvennogo universiteta, n^o 3 (2021) : 74–83. http://dx.doi.org/10.18323/2073-5073-2021-3-74-83.

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Graphene-based polymer nanocomposites are considered a promising class of future materials. The degree of filling, the filler and binder nature, and the shape, size, and mutual arrangement of filler particles determine the properties of a polymer composite material. The destruction of nanoparticles aggregates occurs most effectively in liquid media under the action of ultrasonic vibrations. The authors proposed the technique and designed laboratory equipment for ultrasonic treatment of the finely-dispersed graphite suspension, carried out the ultrasonic treatment (UST) of finely-dispersed graphite powder. The suspensions based on graphite with a solvent were obtained. The authors carried out the experiments on producing graphene using the graphite liquid-phase exfoliation method at the ultrasonic treatment with different ultrasonic treatment times, analyzed experimental data, and selected the UST optimal time. The paper contains the results of the study of the effect of the graphite suspension base on the degree of ultrasonic liquid-phase exfoliation of graphite. The most effective synthesis of graphene structures using UST is synthesis from graphite suspensions based on dichloroethane, benzol, and dichlorobenzene. Graphene structures’ output ratio amounts to up to 66 %. The authors developed the technology for producing polymers modified with graphene structures using ultrasonic dispersion. Based on graphene synthesized by the graphite liquid-phase exfoliation, the authors obtained nanopolymers using ultrasonic vibrations, carried out DSC measurements, and studied their strength properties. The limit strength of elastic polymers is from 1.9 to 3.6 MPa at different concentrations of graphene inclusions. The residual elongation of samples within the deviation did not change and amounted to 200 %.

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Pan, Changkang, et Fred L. King. « Direct Determination of Trace Elements in Graphite Matrices Using Modulated Glow Discharge Atomic Absorption Spectrometry ». Applied Spectroscopy 47, n^o 3 (mars 1993) : 300–304. http://dx.doi.org/10.1366/0003702934066730.

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The trace element concentrations in high-purity graphites were determined by atomic absorption spectrometry (AAS) with the use of a modulated glow discharge atomizer. Glow discharge power was modulated at SO Hz to enhance sensitivity and to permit time-resolved atomic absorption measurements. The influence of discharge operating parameters including current, pressure, and plasma sampling on the analytical performance of this technique was investigated. This analytical technique was evaluated in terms of stability, sensitivity, reproducibility, and accuracy. The method of standard additions was used to determine the impurity levels of the standard graphite matrix. Linear analytical calibration curves were constructed for four elements of interest in samples of nuclear-grade graphite. Detection limits for these elements were calculated to be in the tens of parts-per-billion range for graphite matrices.

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Usuda, Teruki, K. Matsuno, Hisao Matsunaga, Keiji Yanase et Masahiro Endo. « Hydrogen-Induced Ductility Loss in Cast Irons ». Materials Science Forum 750 (mars 2013) : 260–63. http://dx.doi.org/10.4028/www.scientific.net/msf.750.260.

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Effect of hydrogen-charging was investigated with respect to the tensile properties of three types of cast irons: JIS FCD400, FCD450 and FCD700. In this study, hydrogen charging led to a marked ductility loss in all the cast irons. The thermal desorption spectroscopy and the hydrogen microprint technique revealed that, in the hydrogen-charged specimens, most of solute hydrogen was diffusive and mainly segregated at graphite, graphite/matrix interface zone and pearlite. In the fracture process of non-charged specimen, neighboring graphites were interconnected with each other mainly by ductile dimple fracture. On the other hand, in the fracture process of hydrogen-charged specimen, the graphites were interconnected by cracks. The difference in the fracture morphology between the non-charged and the hydrogen-charged specimens is attributed to the presence of diffusive hydrogen in graphite and graphite/matrix interface. During early stage of fracture process in hydrogen-charged specimen, the interspace between graphite and matrix is filled with hydrogen gas, which leads to the ductility loss of matrix in the vicinity of graphite. Even after the initiation of crack from graphite, hydrogen is continuously outgassed from graphite and supplied to the crack tip. Therefore, concerning the hydrogen effect on the strength of cast irons, a role of subsurface graphite as a “local hydrogen supplier” should be taken into consideration.

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Hares, Essam, Ahmed H. El-Shazly, M. F. El-Kady et A. S. Hammad. « Enhancing the Hydrophobicity of a Copper Pipe by Electrophoretic Deposition of Graphene Oxide ». Key Engineering Materials 801 (mai 2019) : 153–59. http://dx.doi.org/10.4028/www.scientific.net/kem.801.153.

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Thin film coatings of graphene oxide (GO) onto copper pipe was investigating using electrophoretic deposition (EPD) technique. Graphite oxide was produced from graphite powder by chemical oxidation using modified Hummers' method. An aqueous colloidal suspension of graphene oxide was prepared by exfoliation of the graphite oxide via ultrasonic treatment. GO coatings were deposited on copper pipes through EPD from GO aqueous suspension. The EPD parameters such as voltage, time and particle concentration were optimized to obtain uniform GO coatings. The optimal EPD conditions for well-formed deposits were observed when the operating voltage was equal to 30 V and 90 s deposition time. The thin film coated copper pipe was characterized using various techniques such as SEM, XRD and contact angle. XRD confirmed that GO was reduced during the EPD process itself due to the removal of oxygen containing functional groups. SEM images elucidated the formation of GO thin layer onto copper pipe with thickness 5 μm. The contact angle improved from 70° for bare copper to 102.4° for GO coating.

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Deerattrakul, Varisara, Wisit Hirunpinyopas, Nuttapon Pisitpipathsin, Thanit Saisopa, Montree Sawangphruk, Chakrit Nualchimplee et Pawin Iamprasertkun. « The electrochemistry of size dependent graphene via liquid phase exfoliation : capacitance and ionic transport ». Physical Chemistry Chemical Physics 23, n^o 20 (2021) : 11616–23. http://dx.doi.org/10.1039/d1cp00887k.

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This work explores the capacitance and ionic transport properties of size dependent graphene (from 100 nm to 1 μm) prepared through the liquid phase exfoliation of graphite in which the size of graphene was finely selected using a multi-step centrifugation technique.

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Hussein, Mohamed Khazal, Walaa W. Jameel et Noor Fadhil Athraa Sabah. « Fabrication of Copper-Graphite MMCs Using Powder Metallurgy Technique ». Journal of Engineering 24, n^o 10 (1 octobre 2018) : 49. http://dx.doi.org/10.31026/j.eng.2018.10.04.

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Copper, and its, alloys and composites (being the matrix), are broadly used in the electronic as well as bearing materials due to the excellent thermal and electrical conductivities it has. In this study, powder metallurgy technique was used for the production of copper graphite composite with three volume perc ent of graphite. Processing parameters selected is (900) °C sintering temperature and (90) minutes holding time for samples that were heated in an inert atmosphere (argon gas). Wear test results showed a pronounced improvement in wear resistance as the percent of graphite increased which acts as solid lubricant (where wear rate was decreased by about 88% as compared with pure Cu). Microhardness and compressive strength increased (about 8% and 16%, for each of them) and reached to the maximum values at 1% graphite percentage as compared with pure Cu, then it decreased after that critical graphite concentration. Microstructure test indicated that the dark region in the copper matrix was increased as the percent of graphite increased and the reinforcement particles were homogeneously distributed which means that the powder metallurgy technique is suitable for such task.

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Yang, Yin, Ziyang Wang et Shaobo Zheng. « Secondary Exfoliation of Electrolytic Graphene Oxide by Ultrasound Assisted Microwave Technique ». Nanomaterials 12, n^o 1 (28 décembre 2021) : 68. http://dx.doi.org/10.3390/nano12010068.

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Scalable production of large size and high quality graphene is an important prerequisite to fully realize its commercial applications. Herein, we propose a high-efficient route for preparing few-layer graphene. The secondary exfoliation of unexfoliated graphite flakes from electrochemical exfoliation was achieved by using ultrasonication assisted microwave exfoliation technique. The results show that the as-prepared sample has a C/O of 15.2, a thickness of about 1 nm and a transverse dimension of over 100 nm, and the Raman spectrogram shows low defects upon reduction of the sample. These results suggest that electrolytic graphene can be exfoliated to form graphene nanosheets under ultrasonic-assisted microwave technology, thus indicating that the current method has great potential for synthesizing high-quality graphene at an industrial-scale.

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Barnakov, Ch N., G. P. Khokhlova, A. N. Popova, S. A. Sozinov et Z. R. Ismagilov. « XRD Characterization of the Structure of Graphites and Carbon Materials Obtained by the Low-Temperature Graphitization of Coal Tar Pitch ». Eurasian Chemico-Technological Journal 17, n^o 2 (11 mars 2015) : 87. http://dx.doi.org/10.18321/ectj198.

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The structure of some commercial graphites and carbon materials (CMs) obtained by the low-temperature catalytic graphitization of coal tar pitch with iron salt, needle coke, foamed graphite as the catalysts has been studied. The study was performed using the X-ray diffraction technique with reflections from base plane and their decomposition into two components corresponding to the structural phases of graphite which have different XRD characteristics. Various CMs were compared with respect to the structural phase ratio, distance between polyarene layers in these phases, and sizes of the coherent scattering regions. The (004) reflection provided a better fit of some properties of graphites to the calculated XRD characteristics as compared to calculation from the (002) reflection. In the case of carbonization of coal tar pitch with investigated catalyst additions, prepared carbon materials have a higher degree of graphitization and a crystallite size greater than in the other case of carbonization of the individual pitch. The highest catalytic activity is shown by foamed graphite. It was found that the use of foamed graphite as the catalyst at 800-900 ºC produced carbon materials possessing a crystalline structure with interplanar spacing close to that in commercial graphites, while in the absence of catalyst the coal tar pitch material has an amorphous structure.

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Tarannum, Fatema, Swapneel S. Danayat, Avinash Nayal, Rajmohan Muthaiah, Roshan Sameer Annam et Jivtesh Garg. « Large Enhancement in Thermal Conductivity of Solvent−Cast Expanded Graphite/Polyetherimide Composites ». Nanomaterials 12, n^o 11 (30 mai 2022) : 1877. http://dx.doi.org/10.3390/nano12111877.

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We demonstrate in this work that expanded graphite (EG) can lead to a very large enhancement in thermal conductivity of polyetherimide−graphene and epoxy−graphene nanocomposites prepared via solvent casting technique. A k value of 6.6 W⋅m−1⋅K−1 is achieved for 10 wt% composition sample, representing an enhancement of ~2770% over pristine polyetherimide (k~0.23 W⋅m−1⋅K−1). This extraordinary enhancement in thermal conductivity is shown to be due to a network of continuous graphene sheets over long−length scales, resulting in low thermal contact resistance at bends/turns due to the graphene sheets being covalently bonded at such junctions. Solvent casting offers the advantage of preserving the porous structure of expanded graphite in the composite, resulting in the above highly thermally conductive interpenetrating network of graphene and polymer. Solvent casting also does not break down the expanded graphite particles due to minimal forces involved, allowing for efficient heat transfer over long−length scales, further enhancing overall composite thermal conductivity. Comparisons with a recently introduced effective medium model show a very high value of predicted particle–particle interfacial conductance, providing evidence for efficient interfacial thermal transport in expanded graphite composites. Field emission environmental scanning electron microscopy (FE−ESEM) is used to provide a detailed understanding of the interpenetrating graphene−polymer structure in the expanded graphite composite. These results open up novel avenues for achieving high thermal conductivity polymer composites.

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Chen, Zhao Sheng. « Effect of Preparation Technique on Methyl Orange Sorption Behavior of Exfoliated Graphite ». Advanced Materials Research 284-286 (juillet 2011) : 193–96. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.193.

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Three natural graphite flakes (35, 50 and 80 mesh) were used as raw material. Exfoliated graphite (EG) was prepared by rapidly heating expandable graphite to 1000 °C in a muffle and by irradiating it in a microwave oven with a power of 280 W for 40 s, respectively. The EG samples were used for removing methyl orange (MO) from aqueous solution. The effect of preparation technique of EG (particle size of natural graphite and exfoliation method of expandable graphite) on MO removal properties was investigated, and a higher removal rate was achieved.

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WEI, XIANFENG, YONG HAN et XINPING LONG. « PREPARATION OF C60 BY DETONATION TECHNIQUE ». Modern Physics Letters B 26, n^o 28 (8 octobre 2012) : 1250182. http://dx.doi.org/10.1142/s0217984912501825.

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A mixture of TNT (Trinitrotoluene) and natural graphite was detonated in a vacuum container which was immersed into cooling water; detonation products were collected for detecting. The results of mass spectroscopy, high performance liquid chromatography showed significant signals of C 60, which proved that C 60 could be synthesized by detonating the mixture of TNT/graphite and the detonation pressure was around 12.3 GPa and the detonation temperature was around 1985 K.

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Li, Jiaxing, Xia Liu, Cheng Cheng, Tasawar Hayat, Njud S. Alharbi, Ahmed Alsaedi et Xiangke Wang. « Preparation of micron sized graphite using a spark plasma technique ». RSC Advances 6, n^o 56 (2016) : 50776–79. http://dx.doi.org/10.1039/c6ra07710b.

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Seidl, L., N. Bucher, E. Chu, S. Hartung, S. Martens, O. Schneider et U. Stimming. « Intercalation of solvated Na-ions into graphite ». Energy & ; Environmental Science 10, n^o 7 (2017) : 1631–42. http://dx.doi.org/10.1039/c7ee00546f.

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The reversible intercalation of solvated Na-ions into graphite and the concomitant formation of ternary Na–graphite intercalation compounds (GICs) are studied using several in operando techniques, such as X-ray-diffraction (XRD), electrochemical scanning tunnelling microscopy (EC-STM) and the electrochemical quartz crystal microbalance technique (EQCM).

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Farivar, Farzaneh, Pei Lay Yap, Ramesh Udayashankar Karunagaran et Dusan Losic. « Thermogravimetric Analysis (TGA) of Graphene Materials : Effect of Particle Size of Graphene, Graphene Oxide and Graphite on Thermal Parameters ». C 7, n^o 2 (27 avril 2021) : 41. http://dx.doi.org/10.3390/c7020041.

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Thermogravimetric analysis (TGA) has been recognized as a simple and reliable analytical tool for characterization of industrially manufactured graphene powders. Thermal properties of graphene are dependent on many parameters such as particle size, number of layers, defects and presence of oxygen groups to improve the reliability of this method for quality control of graphene materials, therefore it is important to explore the influence of these parameters. This paper presents a comprehensive TGA study to determine the influence of different particle size of the three key materials including graphene, graphene oxide and graphite on their thermal parameters such as carbon decomposition range and its temperature of maximum mass change rate (Tmax). Results showed that Tmax values derived from the TGA-DTG carbon combustion peaks of these materials increasing from GO (558–616 °C), to graphene (659–713 °C) and followed by graphite (841–949 °C) The Tmax values derived from their respective DTG carbon combustion peaks increased as their particle size increased (28.6–120.2 µm for GO, 7.6–73.4 for graphene and 24.2–148.8 µm for graphite). The linear relationship between the Tmax values and the particle size of graphene and their key impurities (graphite and GO) confirmed in this study endows the use of TGA technique with more confidence to evaluate bulk graphene-related materials (GRMs) at low-cost, rapid, reliable and simple diagnostic tool for improved quality control of industrially manufactured GRMs including detection of “fake” graphene.

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Negrea, Sorina Claudia, Lidia Ani Diaconu, Valeria Nicorescu, Dorian Neidoni, Ana Maria Baciu, Claudia Licurici et Florica Manea. « Comparative testing of Ag/Au/Pt graphene electromodified electrodes in electrochemical detection of tetracycline-emerging pollutant ». Romanian Journal of Ecology & ; Environmental Chemistry 2, n^o 2 (14 octobre 2020) : 153–65. http://dx.doi.org/10.21698/rjeec.2020.219.

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This study aimed to obtain new electrochemically modified electrodes with graphene and Au, Pt, Ag particles considering graphite (GP) and glassy carbon (GC) substrate by applying the chronoamperometry technique to develop the detection protocol of tetracycline (TC) considered as an emerging pollutant in water, using cyclic voltammetry (CV) technique. The graphite-based substrate used for Ag/ Au/ Pt electrodeposition led to the electrode compositions on which TC oxidation process was not diffusion-controlled and as consequence, TC detection failed. TC detection protocols were developed for all Ag/Au /Pt electrodeposited GC and GCGP electrodes. Better limits of TC detection was achieved for Ag electrodeposited on GC-GP at the cathodic potential of 0.460 V/SCE.

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Hendaoui, Ali, et Abdullah Alshammari. « Preparation of Nitrogen-doped Holey Multilayer Graphene Using High-Energy Ball Milling of Graphite in Presence of Melamine ». Materials 16, n^o 1 (26 décembre 2022) : 219. http://dx.doi.org/10.3390/ma16010219.

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Holey graphene, consisting of graphene sheets with in-plane nanopores, has recently attracted more attention as it expands graphene applications to other fields inaccessible by the pristine graphene. To ensure an effective implementation of holey graphene in the market, it is crucial to explore new preparation methods that are simple, cost effective, eco-friendly, versatile, and scalable. While ball milling of graphite in presence of exfoliating agents was found very effective in the preparation of graphene (doped and undoped) and graphene-composites, this technique remains unexplored for the preparation of holey graphene. In the present work, Nitrogen-doped multilayer holey graphene sheets were prepared by an all-solid, one-step procedure based on high-energy ball milling of graphite as the starting material in presence of melamine in a shaker-type mill for 1 hour under ambient conditions. Melamine acted simultaneously as an exfoliating agent to enhance the exfoliation of graphene layers and a diluent to protect graphite against the continuous fragmentation into amorphous carbon during the high-energy “shock” mode of ball milling. The high-energy “shock” mode of ball milling of graphite in presence of melamine induced the formation of multilayer defective graphene as an intermediate product before being converted into N-doped multilayer holey graphene after the removal of the in-plane defects during the milling process. The characterization of the final product confirmed the formation of N-doped multilayer holey graphene with a content in nitrogen as high as 12.96 at.%, making it promising for energy storage and energy conversion applications.

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Rajamani, Praveen Kannan, et Róbert Boros. « The Effect of Filler Orientation and Distribution on the Electrical and Mechanical Properties of Graphene Based Polymer Nanocomposites ». Acta Technica Jaurinensis 11, n^o 4 (30 octobre 2018) : 185–205. http://dx.doi.org/10.14513/actatechjaur.v11.n4.479.

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The aim of my proposed study is to develop an alternative production technique of graphene via in-situ exfoliation of graphite in the hosting polymer matrix. The production process is carried out by an alternative top-down production technique for graphene-based polymer nanocomposites called ‘pressing and folding’ (P&F), via in situ exfoliation of expanded graphite (EG) inside the hosting linear low-density polyethylene (LLDPE) matrix. In this way, the properties of the samples containing different wt % of EG is studied as a function of P&F cycles, corresponding to EG exfoliation and distribution throughout the matrix volume. The results confirm that the EG particles was exfoliated completely and increasingly distributed in LLDPE with the number of cycles, and mainly oriented on the plane of the samples. This find was confirmed by a low in-plane resistivity was found for samples prepared between 50 and 150 cycles.

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Mohd Sofian Alias, Norinsan Kamil Othman, Siti Radiah Mohd Kamarudin, Siti Fatahiyah Mohamad, Mohd Hamzah Harun, Mahathir Mohamed, T. Rida et al. « Encouragement of Graphite and Graphene Oxide Particles on Corrosion Protection Properties for Polyurethane Palm Oil Based UV Curable Coating ». International Journal of Nanoelectronics and Materials (IJNeaM) 16, DECEMBER (26 décembre 2023) : 253–66. http://dx.doi.org/10.58915/ijneam.v16idecember.408.

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This research explores the impact of derivative graphite additives in enhancing the corrosion prevention system of UV curable polyurethane coatings based on palm oil. UV irradiation technique was used in this study to produce cured protection coating. Two types of particles, respectively graphite and graphene oxide were used to understand the differential of both particles in physicomechanical behaviour of the curable coating. The study delves into the formulation and characterization of these coatings, assessing their effectiveness in preventing corrosion. The polymerisation effect by UV irradiation and influence of filler (graphene oxide and graphite) on physical properties of coating were studied by using Fourier Transform Infrared Spectroscopy (FTIR) and gel content together with hardness test. Besides that, X-ray Diffraction (XRD) and Field emission scanning electron microscopy (FESEM) were used to investigate the morphology of curable coating. Meanwhile Electro impedance spectroscopy (EIS) and contact angle measurement were carried out to investigate the related behaviour on corrosion protection properties. All the results were concluded to explain the role of graphite and graphene oxide in curable coating crosslink network. The finding in this study indicates that tortuosity structured which formed by graphite and graphene oxide in UV curable coating matrix were successfully retard corrosion rate per year on mild steel from 31.24 mpy to 43.91 x 10-6 mpy. This work aims to provide valuable insights into the development of eco-friendly and efficient corrosion protection solutions in the realm of coatings and materials science.

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P. Nandakumar, P. Nandakumar, K. N. Amba Sankar, A. Shankar Ganesh, BA Anandh BA. Anandh et R. Deepa R. Deepa. « Electrochemical Performance of Carbon Materials ». Oriental Journal Of Chemistry 38, n^o 3 (30 juin 2022) : 604–9. http://dx.doi.org/10.13005/ojc/380308.

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The surface modification on electrode materials generally improves the electron mobility and surface interactions at carbon materials. Exfoliate graphite has been prepared by the ball milling technique with three different milling time. The graphene oxide, reduced graphene oxide were prepared modified Hummers method and carbon quantum dots was prepared using chemical synthesis-pyrolysis technique. The synthesized materials were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), and investigated the electrochemical performances of Cyclic Voltammetry (CV) analysis to understand their specific capacitance.

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Shanmugharaj, AM, K. Thileep Kumar, G. Sivagaami Sundari, E. Senthil Kumar, A. Ashwini, M. Ramya, P. Varsha, R. Kalaivani, S. Raghu et SH Ryu. « Study on the effect of silica–graphite filler on the rheometric, mechanical, and abrasion loss properties of styrene–butadiene rubber vulcanizates ». Journal of Elastomers & ; Plastics 51, n^o 4 (13 juillet 2018) : 359–78. http://dx.doi.org/10.1177/0095244318787560.

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Silica–graphite filler was prepared via two-step grafting procedure by grafting silica particles onto the expanded graphite. In the first step, isocyanatopropyltriethoxysilane was chemically introduced onto the silica aggregates, which was followed by grafting onto the expanded graphite via urethane linkage in the second step. Successful grafting of silica aggregates onto the graphite was corroborated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The presence of a thin graphene layer on silica aggregates corroborated using transmission electron microscopy confirmed the grafting of silica aggregates onto the graphite surface. Styrene–butadiene rubber (SBR) composites with various silica–graphite loadings were prepared by melt processing technique to generate pristine silica and silica–graphite-filled elastomeric composites. Rheometric cure studies revealed that the torque difference (Δ S) increased with pristine silica loading, when compared to the unfilled SBR system, and this effect is more pronounced on loading silica–graphite filler. Improvements in mechanical properties such as modulus and tensile strength were observed with increasing loading of silica particles and this effect is more pronounced on loading silica–graphite fillers, indicating that this is due to the rise in the elastomer–filler interactions in the silica–graphite-loaded SBR systems. This fact was further corroborated using bound rubber content and equilibrium swelling ratios of the unvulcanized and vulcanized SBR composites.

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Iijima, Sumio. « Closed graphene nanostructures ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 194–95. http://dx.doi.org/10.1017/s0424820100137343.

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Graphene is named a single sheet of graphite, or a 2-D carbon hexagons network. The graphene structure has been observed in partially graphitized carbon which is familiar to electron microscopists and its HRTEM image properties were analyzed previously in detail. C60 molecules, which has brought a great excitements in interdisciplinary fields of science and technology, is basically the same graphene structure with a curvature. The individual C60 molecule can be imaged without difficulty by HRTEM. Many of fundamental problems with the molecule however are not solved by the HRTEM technique. On the other hand, carbon nanotubes, a family of the fullerene and discovered serendipitously by the present author5, are an ideal subject for the HRTEM investigation and in fact their structural details can only be analyzed by this technique. The present talk reviews the carbon nanotubes and related structures with an emphasis of usefulness of the HRTEM.Search for the multi-shell graphite particles leads to unexpected discovery of carbon nanotubes which grow on a cathode in a carbon-arc chamber for the C60 production.

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Sloan, Forrest E. « Chemical Attack of Graphite/Epoxy by Hydrogen Peroxide ». Applied Spectroscopy 46, n^o 3 (mars 1992) : 524–28. http://dx.doi.org/10.1366/0003702924125366.

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Techniques for studying the mechanisms of chemical corrosion in fiber-reinforced plastics are of considerable importance. The most common analysis technique for studying chemical changes in polymers is Fourier transform infrared (FT-IR) spectroscopy. For polymers reinforced with graphite fibers, however, study of the matrix is hindered by the presence of the graphite, which strongly absorbs IR radiation in a broad band of wavelengths. The purpose of this study was to investigate the degradation of AS-4/3501-5a graphite/epoxy composite material exposed to solutions of hydrogen peroxide. Evidence was also sought for degradation in high pH (up to pH = 12) solutions. After long-term environmental exposure, a simple gravity flotation technique was used to separate the epoxy matrix from the graphite fibers for FT-IR analysis. The resulting spectroscopic evidence indicates that hydrogen peroxide attacks the secondary amines in the cured epoxy structure. No evidence of attack by high pH solutions was found.

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Goh, Simon Chun Kiat, Wenshuai Wu, Chun Fei Siah, Derek Keng Yang Phee, Aiqun Liu et Beng Kang Tay. « Surface disinfection with silver loaded pencil graphite prepared with green UV photoreduction technique ». Nanotechnology 33, n^o 23 (15 mars 2022) : 235602. http://dx.doi.org/10.1088/1361-6528/ac54dd.

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Abstract Carbon-based materials have been studied for their antimicrobial properties. Previously, most antimicrobial studies are investigated with suspended nanoparticles in a liquid medium. Most works are often carried out with highly ordered pyrolytic graphite. These materials are expensive and are not viable for mass use on high-touch surfaces. Additionally, highly antimicrobial silver nanoparticles are often incorporated onto substrates by chemical reduction. At times, harmful chemicals are used. In this work, low-cost graphite pencils are mechanically exfoliated and transferred onto Si substrates. The sparsely-covered graphite flakes are treated by either plasma O2 or UV irradiation. Subsequently, Ag is photo reduced in the presence of UV onto selected graphite flake samples. It is found that graphite flake surface topography and defects are dependent on the treatment process. High surface roughness and (defects density, I D/I G) are induced by plasma O2 follows by UV and pristine graphite flake as follows: 6.45 nm (0.62), 4.96 nm (0.5), 3.79 nm (0.47). Antimicrobial tests with E. coli reveal high killing efficiency by photoreduced Ag-on-graphite flake. The reversible effect of Ag leaching can be compensated by repeating the photoreduction process. This work proposes that UV treatment is a promising technique over that of plasma O2 in view that the latter treated surface could repel bacteria resulting in lower bacteria-killing efficiency.

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Palomba, Mariano, Gianfranco Carotenuto, Angela Longo, Andrea Sorrentino, Antonio Di Bartolomeo, Laura Iemmo, Francesca Urban et al. « Thermoresistive Properties of Graphite Platelet Films Supported by Different Substrates ». Materials 12, n^o 21 (5 novembre 2019) : 3638. http://dx.doi.org/10.3390/ma12213638.

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Large-area graphitic films, produced by an advantageous technique based on spraying a graphite lacquer on glass and low-density polyethylene (LDPE) substrates were studied for their thermoresistive applications. The spray technique uniformly covered the surface of the substrate by graphite platelet (GP) unities, which have a tendency to align parallel to the interfacial plane. Transmission electron microscopy analysis showed that the deposited films were composed of overlapped graphite platelets of different thickness, ranging from a few tens to hundreds of graphene layers, and Raman measurements provided evidence for a good graphitic quality of the material. The GP films deposited on glass and LDPE substrates exhibited different thermoresistive properties during cooling–heating cycles in the −40 to +40 °C range. Indeed, negative values of the temperature coefficient of resistance, ranging from −4 × 10−4 to −7 × 10−4 °C−1 have been observed on glass substrates, while positive values varying between 4 × 10−3 and 8 × 10−3 °C−1 were measured when the films were supported by LDPE. These behaviors were attributed to the different thermal expansion coefficients of the substrates. The appreciable thermoresistive properties of the graphite platelet films on LDPE could be useful for plastic electronic applications.

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Kumar, S. R., et Kumar Anurag. « Synthesis and characterization of graphene via electrochemical exfoliation technique and study its electrochemical properties ». IOP Conference Series : Materials Science and Engineering 1291, n^o 1 (1 septembre 2023) : 012018. http://dx.doi.org/10.1088/1757-899x/1291/1/012018.

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Abstract In this study, we present a one-pot approach for the large-scale synthesis of multilayer to few-layer graphene nanosheets in an aqueous medium that is cost-effective, environmentally friendly, high-yielding, and simple. This electrochemical exfoliation method produces low defect and high yield graphene nanosheet products and is more efficient than chemical exfoliation methods. Two highly oriented pyrolytic graphite plates (HOPG) are utilized as the anode and cathode in this method, which also incorporates two electrode geometry configurations. XRD, HRTEM, AFM, XPS, and Raman spectroscopy are used to describe graphene nano-sheets. Raman characterization supports graphene’s inherent qualities. By using cyclic voltammetry, the electrochemical performance of the produced nano-sheets is evaluated.

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Arapov, Kirill, Robert Abbel, Gijsbertus de With et Heiner Friedrich. « Inkjet printing of graphene ». Faraday Discuss. 173 (2014) : 323–36. http://dx.doi.org/10.1039/c4fd00067f.

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The inkjet printing of graphene is a cost-effective, and versatile deposition technique for both transparent and non-transparent conductive films. Printing graphene on paper is aimed at low-end, high-volume applications,i.e., in electromagnetic shielding, photovoltaics or,e.g., as a replacement for the metal in antennas of radio-frequency identification devices, thereby improving their recyclability and biocompatibility. Here, we present a comparison of two graphene inks, one prepared by the solubilization of expanded graphite in the presence of a surface active polymer, and the other by covalent graphene functionalization followed by redispersion in a solvent but without a surfactant. The non-oxidative functionalization of graphite in the form of a donor-type graphite intercalation compound was carried out by a Birch-type alkylation, where graphene can be viewed as a macrocarbanion. To increase the amount of functionalization we employed a graphite precursor with a high edge to bulk carbon ratio, thus, allowing us to achieve up to six weight percent of functional groups. The functionalized graphene can be readily dispersed at concentrations of up to 3 mg ml⁻¹in non-toxic organic solvents, and is colloidally stable for more than 2 months. The two inks are readily inkjet printable with good to satisfactory spreading. Analysis of the sheet resistance of the deposited films demonstrated that the inks based on expanded graphite outperform the functionalized graphene inks, possibly due to the significantly larger graphene sheet size in the former, which minimizes the number of sheet-to-sheet contacts along the conductive path. We found that the sheet resistance of printed large-area films decreased with an increase of the number of printed layers. Conductivity levels reached approximately 1–2 kΩ □⁻¹for 15 printing passes, which roughly equals a film thickness of 800 nm for expanded graphite based inks, and 2 MΩ □⁻¹for 15 printing passes of functionalized graphene, having a film thickness of 900 nm. Our results show that ink preparation and inkjet printing of graphene-based inks is simple and efficient, and therefore has a high potential to compete with other conductive ink formulations for large-area printing of conductive films.

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Torres, Luis, Luis Gomez Armas et Antonio Carlos Seabra. « Optimization of Micromechanical Cleavage Technique of Natural Graphite by Chemical Treatment ». Graphene 03, n^o 01 (2014) : 1–5. http://dx.doi.org/10.4236/graphene.2014.31001.

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Hares, Essam, Ahmed Hassan El-Shazly, Marwa Farouk El-Kady, Kholoud Madih, Hamdiya Orleans-Boham et Abdallah Yousef Mohammed Ali. « Anodic Aqueous Electrophoretic Deposition of Graphene Oxide on Copper Using Different Cathode Materials ». Materials Science Forum 1008 (août 2020) : 21–27. http://dx.doi.org/10.4028/www.scientific.net/msf.1008.21.

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The effect of four different cathode materials on the anodic deposition of graphene oxide (GO) nanosheets was studied experimentally. First, synthesis of graphite oxide from graphite powder was done by modified Hummers' method. Ultrasonic technique was adopted for the preparation of the stable aqueous suspension of GO by using liquid exfoliation of graphite oxide. Deposition of GO coating on copper sheets (the anode) was done via electrophoretic deposition (EPD) at the same operating condition (5V, 2 min, concentration of 0.5 mg/ml of GO per deionized water) with different cathode materials (copper, stainless steel, aluminum and graphite). The coatings’ morphological and microstructure were investigated using scanning electron microscope (SEM) and the effect of the current density in the EPD process was obtained. The change in the deposition weight was also measured. It was ascertained that the cathode’s material is a major factor can affect the GO’s EPD process and the characteristics of the final coating.

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Namsar, Orapim, Thanaphat Autthawong, Viratchara Laokawee, Ruttapol Boonprachai, Mitsutaka Haruta, Hiroki Kurata, Aishui Yu, Torranin Chairuangsri et Thapanee Sarakonsri. « Improved electrochemical performance of anode materials for high energy density lithium-ion batteries through Sn(SnO2)–SiO2/graphene-based nanocomposites prepared by a facile and low-cost approach ». Sustainable Energy & ; Fuels 4, n^o 9 (2020) : 4625–36. http://dx.doi.org/10.1039/d0se00597e.

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Novel anode materials for lithium-ion batteries, nanocomposites of Sn (or SnO₂) and SiO₂ with graphene-based sheets (GO, rGO and NrGO), were synthesized by a facile and low-cost technique. The capacity of all composites was relatively high as compared to traditional graphite.

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Wang, Yuzhou, Xianye Zhang, Haihui Liu et Xingxiang Zhang. « SMA-Assisted Exfoliation of Graphite by Microfluidization for Efficient and Large-Scale Production of High-Quality Graphene ». Nanomaterials 9, n^o 12 (21 novembre 2019) : 1653. http://dx.doi.org/10.3390/nano9121653.

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In this paper, the sodium salt of styrene-maleic anhydride copolymer (SMA) was used as a stabilizer in the process of graphite exfoliation to few-layer graphene using the technique of microfluidization in water. This method is simple, scalable, and cost-effective, and it produces graphene at concentrations as high as 0.522 mg mL−1. The generated high-quality graphene consists of few-layer sheets with a uniform size of less than 1 μm. The obtained graphene was uniformly dispersed and tightly integrated into a polyamide 66 (PA66) matrix to create high-performance multifunctional polymer nanocomposites. The tensile strength and thermal conductivity of 0.3 and 0.5 wt% EG/PA66 composites were found to be ~32.6% and ~28.8% greater than the corresponding values calculated for pure PA66, respectively. This confirms that the new protocol of liquid phase exfoliation of graphite has excellent potential for use in the industrial-scale production of high-quality graphene for numerous applications.

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Mbambo, Makhangela C., Saleh Khamlich, Touria Khamliche, Bakang M. Mothudi et Malik Maaza. « Pulsed Nd:YAG laser assisted fabrication of graphene nanosheets in water ». MRS Advances 3, n^o 42-43 (2018) : 2573–80. http://dx.doi.org/10.1557/adv.2018.275.

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AbstractGraphene nanosheets were prepared by pulsed Nd:YAG laser ablation of graphite target in H2O under ambient conditions. The synthesized graphene nanosheets were characterized by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman spectroscopy and Selected Area Electron Diffraction (SAED). The obtained structural and morphological analysis confirmed that the graphene nanosheets could be formed in an aqueous medium via one step method where a nanosecond pulsed near-infrared (NIR) laser (λ = 1064 nm) is used to ablate the surface of a pure graphite target. Compared to other used chemical methods to synthesis graphene nanosheets, laser ablation is an easy, versatile, environmental friendly and rapidly growing method for the synthesis of nanostructured materials such as graphene nanosheets. This technique showed normal operation in liquid medium (i.e. water or organic) under ambient conditions. Our study confirmed the great potential of laser ablation in liquid method for the fabrication of graphene nanosheets based nanofluids wich has a potential applicatiuon as a heat transfer fluid.

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Glukharev, Artem, Oleg Glumov, Ivan Smirnov, Evgeniy Boltynjuk, Olga Kurapova et Vladimir Konakov. « Phase Formation and the Electrical Properties of YSZ/rGO Composite Ceramics Sintered Using Silicon Carbide Powder Bed ». Applied Sciences 12, n^o 1 (24 décembre 2021) : 190. http://dx.doi.org/10.3390/app12010190.

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Fully stabilized zirconia/graphene composites are very promising advanced structural materials having mixed ion–electron conductivity for energy storage and energy conversion applications. The existing methods of the composite manufacturing have a number of disadvantages that limit their practical use. Thus, the search for new sintering methods is an actively developing area. In this work, we report for the first time the application of the SiC powder bed sintering technique for fully stabilized zirconia (YSZ) composite fabrication. The reduced graphene oxide (rGO) was used as a graphene derivative. As a result, well-formed ceramics with high density and crystallinity, the maximal microhardness of 13 GPa and the values of the ionic conductivity up to 10−2 S/cm at 650 °C was obtained. The effects of the sintering conditions and rGO concentration on the microstructure and conductivities of ceramics are discussed in detail. The suggested powder bed sintering technique in a layered graphite/SiC/graphite powder bed allowed well-formed dense YSZ/rGO ceramics fabrication and can become a suitable alternative to existing methods for various oxide ceramic matrix composite fabrication: both conventional sintering and non-equilibrium (SPS, flash sintering) approaches.

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Omidvar, Hamid, Mohammad Sajjadnejad, Guy Stremsdoerfer, Yunny Meas et Ali Mozafari. « Characterization of NiBP-graphite composite coatings deposited by dynamic chemical plating ». Anti-Corrosion Methods and Materials 62, n^o 2 (2 mars 2015) : 116–22. http://dx.doi.org/10.1108/acmm-11-2013-1320.

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Purpose – This paper aims to coat ternary composite NiBP-graphite films by Dynamic Chemical Plating “DCP” technique with a growth rate of at least 5 μm/h, which makes this technique a worthy candidate for production of composite films. Electroless nickel plating method can be used to deposit nickel–phosphorous and nickel–boron coatings on metals or plastic surface. However, restrictions such as toxicity, short lifetime of the plating-bath and limited plating rate have limited applications of conventional electroless processes. Design/methodology/approach – DCP is an alternative for producing metallic deposits on non-conductive materials and can be considered as a modified electroless coating process. Using a double-nozzle gun, two different solutions containing the precursors are sprayed simultaneously and separately onto the surface. With this technique, NiBP-graphite films are fabricated and their corrosion and tribological properties are investigated. Findings – With a film thickness of 2 μm, tribological analysis confirms that these coatings have favorable anti-friction and anti-wear properties. Corrosion resistance of NiBP-graphite composite films was investigated, and it was found that graphite incorporation significantly enhances corrosion resistance of NiBP films. Originality/value – DCP is faster and simpler to perform compared to other electroless deposition techniques. Using a double-nozzle gun, metal salt solution and reducing agents are sprayed to the surface, forming a deposit. Previously, coatings such as Cu, Cu-graphite, Cu-PTFE, Ni-B-TiO2, Ni-P, Ni-B-P and Ni-B-Zn with favorable compactness and adherence by DCP were reported. In this paper, the authors report the application of the DCP technique for depositing NiBP-PTFE nanocomposite films.

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Tsai, W. H., et J. C. S. Yang. « Nondestructive Evaluation of Composite Structures Using System Identification Technique ». Journal of Engineering Materials and Technology 110, n^o 2 (1 avril 1988) : 134–39. http://dx.doi.org/10.1115/1.3226021.

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A system identification technique is presented for nondestructive test to detect and to characterize the existence and location of cracks and other damages in composite structures. Various composite structures, including Kevlar-epoxy plate, graphite epoxy ring, and graphite-epoxy coupon have been tested for different damages such as crack, delamination, impact damage, fatigue damage, etc. In addition, the correlation between severity of any type of the damages mentioned above and changes in identified system parameters has also been systematically studied.

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Muhammad Arif Bhatti, Muhammad Arif Bhatti, Kamran Raza Kazmi Kamran Raza Kazmi, Samreen Zahra Samreen Zahra et Ansar Mehmood and Rashid Mehmood Ansar Mehmood and Rashid Mehmood. « Beneficiation Study on Low-Grade Graphite Ore of Shounter Valley, Azad Kashmir, Pakistan ». Journal of the chemical society of pakistan 42, n^o 1 (2020) : 1. http://dx.doi.org/10.52568/000617.

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A low-grade graphite ore originating from Kael area, Shounter Valley, Azad Kashmir, assaying 8.90% graphite content was upgraded by froth flotation technique to produce a commercial grade graphite concentrate. Mineral phases present in the ore were identified by using X-ray diffraction (XRD) technique. The variables of flotation process such as particle size of the feed, pH of the pulp, % solids of the pulp, speed of impeller, type and quantity of collecting and frothing agents, conditioning time and froth collecting time were optimized to get maximum grade and recovery of graphite mineral. The pH of the pulp was adjusted with sodium carbonate. Kerosene oil was used as collector while pine oil as frother respectively. Sodium silicate was employed as depressant. The grade of the final graphite concentrate produced was 85.80% C with overall recovery of 86.00%. Its surface morphology was studied using SEM-EDX technique while grain size by laser particle size analyzer.

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Muhammad Arif Bhatti, Muhammad Arif Bhatti, Kamran Raza Kazmi Kamran Raza Kazmi, Samreen Zahra Samreen Zahra et Ansar Mehmood and Rashid Mehmood Ansar Mehmood and Rashid Mehmood. « Beneficiation Study on Low-Grade Graphite Ore of Shounter Valley, Azad Kashmir, Pakistan ». Journal of the chemical society of pakistan 42, n^o 1 (2020) : 1. http://dx.doi.org/10.52568/000617/jcsp/42.01.2020.

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A low-grade graphite ore originating from Kael area, Shounter Valley, Azad Kashmir, assaying 8.90% graphite content was upgraded by froth flotation technique to produce a commercial grade graphite concentrate. Mineral phases present in the ore were identified by using X-ray diffraction (XRD) technique. The variables of flotation process such as particle size of the feed, pH of the pulp, % solids of the pulp, speed of impeller, type and quantity of collecting and frothing agents, conditioning time and froth collecting time were optimized to get maximum grade and recovery of graphite mineral. The pH of the pulp was adjusted with sodium carbonate. Kerosene oil was used as collector while pine oil as frother respectively. Sodium silicate was employed as depressant. The grade of the final graphite concentrate produced was 85.80% C with overall recovery of 86.00%. Its surface morphology was studied using SEM-EDX technique while grain size by laser particle size analyzer.

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Liu, Ruili, Huijun Cao, Zuobing Nie, Shihui Si, Xueliang Zhao et Xiaoming Zeng. « A disposable expanded graphite paper electrode with self-doped sulfonated polyaniline/antimony for stripping voltammetric determination of trace Cd and Pb ». Analytical Methods 8, n^o 7 (2016) : 1618–25. http://dx.doi.org/10.1039/c5ay03094c.

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Park, Jong Hyun, Hana Yoon, Younghyun Cho et Chung-Yul Yoo. « Investigation of Lithium Ion Diffusion of Graphite Anode by the Galvanostatic Intermittent Titration Technique ». Materials 14, n^o 16 (19 août 2021) : 4683. http://dx.doi.org/10.3390/ma14164683.

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Graphite is used as a state-of-the-art anode in commercial lithium-ion batteries (LIBs) due to its highly reversible lithium-ion storage capability and low electrode potential. However, graphite anodes exhibit sluggish diffusion kinetics for lithium-ion intercalation/deintercalation, thus limiting the rate capability of commercial LIBs. In order to determine the lithium-ion diffusion coefficient of commercial graphite anodes, we employed a galvanostatic intermittent titration technique (GITT) to quantify the quasi-equilibrium open circuit potential and diffusion coefficient as a function of lithium-ion concentration and potential for a commercial graphite electrode. Three plateaus are observed in the quasi-equilibrium open circuit potential curves, which are indicative of a mixed phase upon lithium-ion intercalation/deintercalation. The obtained diffusion coefficients tend to increase with increasing lithium concentration and exhibit an insignificant difference between charge and discharge conditions. This study reveals that the diffusion coefficient of graphite obtained with the GITT (1 × 10−11 cm2/s to 4 × 10−10 cm2/s) is in reasonable agreement with literature values obtained from electrochemical impedance spectroscopy. The GITT is comparatively simple and direct and therefore enables systematic measurements of ion intercalation/deintercalation diffusion coefficients for secondary ion battery materials.

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Brodu, Etienne, Emmanuel Bouzy, Jean Jacques Fundenberger, Benoit Beausir, Lydia Laffont et Jacques Lacaze. « Crystallography of Growth Blocks in Spheroidal Graphite ». Materials Science Forum 925 (juin 2018) : 54–61. http://dx.doi.org/10.4028/www.scientific.net/msf.925.54.

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A better understanding of spheroidal graphite growth is expected in a near future thanks to widespread use of transmission electron microscopy. However, common transmission electron microscopy is quite time consuming and new indexing techniques are being developed, among them is transmission Kikuchi diffraction in a scanning electron microscope, a recent technique derived from electron backscatter diffraction. In the present work, on-axis transmission Kikuchi diffraction in scanning electron microscope, completed by transmission electron microscopy, was used with the objective of producing new observations on the microstructure of spheroidal graphite. This study shows that disorientations between blocks and sectors in spheroidal graphite are quite large in the early growth stage, which may be indicative of a competition process selecting the best orientations for achieving radial growth along thecdirection of graphite.

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Wang, Zhigang, Jun Li et Daquan Li. « Analysis of tribological properties of graphite and aluminum composite materials prepared by powder metallurgy technique ». Materials Express 10, n^o 5 (1 mai 2020) : 663–70. http://dx.doi.org/10.1166/mex.2020.1692.

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In order to make full use of the wear resistance and antifriction of the mixed reinforced particles, improve the performance and utilization rate of the composite material, and reduce its wear amount, in this study, graphite and aluminum composite materials with different graphite concentration were prepared by powder metallurgy process. On this basis, the influence of different graphite concentration on the friction coefficient and wear amount of composite samples and different load on the wear amount of composite materials were discussed and analyzed. The results show that with the increase of graphite content, the friction coefficient and wear amount of the composite will decrease correspondingly. When the load is less than 30 N, the wear curve of the sample changes steadily. When the load is more than 30 N, the wear will increase sharply. Therefore, the analysis of the tribological properties of the graphite and aluminum composites based on the powder metallurgy process plays an important role in improving the utilization rate of the composite and reducing its wear.

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