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Journal articles on the topic 'Graphite nanopowder'

Author: Grafiati

Published: 5 June 2025

Last updated: 15 July 2025

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Cazzanelli, Massimo, Luca Basso, Claudio Cestari, et al. "Fluorescent Nanodiamonds Synthesized in One-Step by Pulsed Laser Ablation of Graphite in Liquid-Nitrogen." C 7, no. 2 (2021): 49. http://dx.doi.org/10.3390/c7020049.

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In this work, we present a relevant upgrade to the technique of pulsed laser ablation of fluorescent nanodiamonds (NDs), relying on an automatized graphite-target movement maintaining a constant level of liquid nitrogen over its surface during hours of deposition. Around 60 mg of NDs nanopowder was synthesized and optomagnetically characterized to assess its optical quality. Chemical purification of the ablated nanopowders, which removes the graphitic byproducts, permits to obtain pure fluorescent NDs with an efficiency of 7 ± 1% with respect to the total nanopowder mass. This value compares positively with the efficiency of other commercial NDs synthesis techniques such as detonation, cavitation, and high pressure–high temperature.

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Kozub, Barbara, Jan Kazior, and Aneta Szewczyk-Nykiel. "Sintering Kinetics of Austenitic Stainless Steel AISI 316L Modified with Nanographite Particles with Highly Developed BET Specific Surface Area." Materials 13, no. 20 (2020): 4569. http://dx.doi.org/10.3390/ma13204569.

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The subject of this work was the study of processes occurring during sintering of water atomized AISI 316L austenitic stainless steel powder modified by the addition of graphite nanoparticles. The main purpose of the work was to determine the effect of modification of the AISI 316L stainless steel austenitic powder by the addition of graphite nanopowder on the sintering kinetics and oxide reduction mechanism. The phenomena occurring during the sintering process and oxide reduction mechanisms were subjected to detailed characterizations. Mixtures with two types of nanopowder with a high BET (measurement technique of the specific surface area of materials based on Brunauer–Emmett–Teller theory) specific surface area of 350 and 400 m2/g and for comparison with graphite micropowder with a poorly developed BET specific surface area of 15 m2/g were tested. The conducted thermal analysis showed that the samples made of austenitic stainless steel doped with 0.2% and 0.3% by weight graphite nanopowder with a BET specific surface area of 400 m2/g, sintered best the oxide reduction reactions, with a more intensive participation of carbon, for these samples.

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David, B., N. Pizúrová, O. Schneeweiss, et al. "Annealing Behaviour of Fe-C-N Nanopowder: Formation of Iron/Graphite Core-Shell Structured Nanoparticles." Materials Science Forum 482 (April 2005): 187–90. http://dx.doi.org/10.4028/www.scientific.net/msf.482.187.

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We are reporting the core-shell structured iron/graphite nanoparticles formed by annealing of a nanopowder. The original Fe-C-N based nanopowder has been synthesized by the laser pyrolysis of gas phase reactants. TEM, XRD, Raman spectroscopy, Mössbauer spectroscopy and magnetic measurements were used for its characterization. Nanopowder was heated up to 800°C at ~ 1 Pa vacuum. Presence of iron nanoparticles with the mean diameter of 40 nm in the annealed state of the nanopowder was confirmed from the width of α-Fe X-ray diffraction lines and their core-shell structure was observed under TEM.

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Sharin, P. P., A. V. Sivtseva, and V. I. Popov. "Air-thermal oxidation of diamond nanopowders obtained by the methods of mechanical grinding and detonation synthesis." Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya, no. 4 (December 10, 2022): 67–83. http://dx.doi.org/10.17073/1997-308x-2022-4-67-83.

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In this work, using the methods of X-ray phase analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy, the features of the impact of annealing in air within the temperature range of t = 200÷÷550 °C on the morphology, elemental and phase composition, chemical state and structure of primary particles of nanopowders obtained by grinding natural diamond and the method of detonation synthesis are studied. It is shown that heat treatment in air at given values of temperature and heating time does not affect the elemental composition and atomic structure of primary particles of nanopowders obtained both by the methods of detonation synthesis (DND) and natural diamond grinding (PND). Using XPS, Raman spectroscopy, and transmission electron microscopy, it has been found that annealing in air within the temperature range of 400–550 °C results in the effective removal of amorphous and graphite-like carbon atoms in the sp2- and sp3-states from diamond nanopowders by oxidation with atmospheric oxygen. In the original DND nanopowder, containing about 33.2 % of non-diamond carbon atoms of the total number of carbon atoms, after annealing for 5 h at a temperature of 550 °C, the relative number of nondiamond carbon atoms in the sp2-state decreased to ~21.4 %. In this case, the increase in the relative number of carbon atoms in the sp3-state (in the lattice of the diamond core) and in the composition of oxygen-containing functional groups ranged from ~39.8 % to ~46.5 % and from ~27 % to ~32.1 %, respectively. In the PND nanopowder, which prior to annealing contains about 10.6 % of non-diamond carbon atoms in the sp2-state of the total number of carbon atoms, after annealing under the same conditions as the DND nanopowder, their relative number decreased to 7.1 %. The relative number of carbon atoms in the sp3-state increased from 72.9 % to 82.1 %, and the proportion of carbon atoms in the composition of oxygen-containing functional groups also slightly increased from 10.2 % to 10.8 %. It is demonstrated that the annealing of PND and DND nanopowders in air leads to a change in their color, they become lighter as a result of oxidation of non-diamond carbon by atmospheric oxygen. The maximum effect is observed at a temperature of 550 °C and an annealing time of 5 h. In this case, the weight loss of PND and DND nanopowders after annealing was 5.37 % and 21.09 %, respectively. The significant weight loss of DND nanopowder compared to PND is primarily caused by the high content of non-diamond carbon in the initial state and the high surface energy of primary particles due to their small size.

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David, B., N. Pizúrová, O. Schneeweiss, Petr Bezdička, I. Morjan, and R. Alexandrescu. "Iron/Graphite Core-Shell Structured Nanoparticles Prepared by Annealing of Nanopowder." Materials Science Forum 480-481 (March 2005): 469–76. http://dx.doi.org/10.4028/www.scientific.net/msf.480-481.469.

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We present magnetic and morphological characterization of iron- and iron-carbide- based nanopowder obtained by the laser synthesis from sensitized gas phase mixture containing acetylene and iron pentacarbonyl vapors. The analysis was performed on the as-prepared material and the annealed material. The results of TEM, XRD, Mössbauer and magnetic measurements are reported. Phase transformations taking place during annealing of the nanopowder when core-shell nanoparticles appear are discussed.

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Cho, Namtae, Kathleen G. Silver, Yolande Berta, Robert F. Speyer, Noel Vanier, and Cheng-Hung Hung. "Densification of carbon-rich boron carbide nanopowder compacts." Journal of Materials Research 22, no. 5 (2007): 1354–59. http://dx.doi.org/10.1557/jmr.2007.0155.

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The densification behavior of 20–40-nm graphite-coated B4C nano-particles was studied using dilatometry, x-ray diffraction, and electron microscopy. The sintering onset temperature was higher than expected from a nanoscale powder (∼1500 °C); remnant B2O3 kept particles separated until B2O3 volatilization, and the graphite coatings imposed particle-to-particle contact of a substance more refractory than B4C. Solid-state sintering (1500–1850 °C) was followed by a substantial slowing of contraction rate attributed to the formation of eutectic liquid droplets more than 10× the size of the original nano-particles. These droplets were induced to form well below the B4C-graphite eutectic temperature by the high surface energy of nanoparticles. They were interpreted to have quickly solidified to form a vast number of voids in particle packing, which in turn, impeded detection of continued solid-state sintering. Starting at 2200 °C, a permanent and interconnected liquid phase formed, which facilitated rapid contraction by liquid phase sintering and/or compact slumping.

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Kozub, Barbara, Marimuthu Uthayakumar, and Jan Kazior. "The Influence of Nanographite Addition on the Compaction Process and Properties of AISI 316L Sintered Stainless Steel." Materials 15, no. 10 (2022): 3629. http://dx.doi.org/10.3390/ma15103629.

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This paper presents the effect of graphite addition on the pressing process and selected mechanical properties of AISI 316L austenitic stainless steel. The graphite powders used in this study differed in the value of the specific surface area of the particles, which were 15 (micropowder), 350, and 400 m2/g (nanopowder). Mixtures with the addition of lubricants—stearic acid and Kenolube—were also created, for comparison purposes. The scope of the tests included compressibility of blends, measurements of the ejection force while removing the compacts from the die, micro-structural studies, a static tensile test, a three-point bending test, a Kc impact test, Rockwell hardness, and Vickers microhardness measurements. The study demonstrated that the addition of graphite nanopowder to the studied steel acts as a lubricant, providing a significant improvement in lubricity during the pressing process. Moreover, the addition of nanographite allowed for a significant increase in the mechanical properties studied in this work; it was observed that, for the sinters made of mixtures with a higher graphite content and with a large specific surface area of its particles, better values for the tested properties were obtained.

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Iannitto, Robyn, Dante Filice, Ali Asgarian, Gaofeng Li, and Sylvain Coulombe. "Novel Nonthermal Plasma Injector for the in-Flight Synthesis and Coating of Battery Materials." ECS Meeting Abstracts MA2024-02, no. 10 (2024): 5116. https://doi.org/10.1149/ma2024-02105116mtgabs.

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As CO2 emissions continue to rise and the demands for electric vehicles and energy storage grow, efforts need to be made to produce higher performing lithium ion batteries (LIBs). Therefore, it is critical to improve the performance of the anode materials. Graphite has gained recognition as the most popular anode for commercial LIBs due to its low cost, low toxicity and cycle stability. However, there are a number of disadvantages with graphite, such as its limited storage capacity, which hinders further LIB development. As a result, silicon has emerged as a promising anode material due to its high charge storage capacity, which is approximately 10 times larger than graphite. Despite this, silicon as an anode for LIBs faces its own challenges, namely its extreme volume expansion during the lithiation and delithiation process, which leads to poor cycle performance. To combat this, silicon nanoparticles with carbon coatings have been identified as a promising candidate for LIBs anodes. The carbon will provide continuous conduction during cycling and prevent pulverization, and the core-shell structure will reduce volumetric expansion and therefore improve the anode stability. Ideally, silicon nanopowder (core) with carbon coating (functional shell) should be integrated in a single process. This would prevent the synthesized nanoparticle from immediately oxidizing upon contact with air or agglomerating, irreversibly affecting the sought-after surface properties. However, the successful one-step synthesis of core-shell nanopowders still remains a challenge. Therefore, the bottleneck for the integration of silicon anodes with carbon coatings into LIBs is the development of a cost-effective and environmentally friendly synthesis method. A number of industries have adopted inductively coupled plasma (ICP) reactors since they are well-suited for large scale production of nanopowders, but these currently lack the ability for in-situ modification of nanopowder surfaces. This is where non-thermal plasmas (NTPs) come into play. NTPs host high-temperature electrons that initiate the formation of chemical radicals and ions in the gas phase which, upon reaction with a nanopowder surface, form coatings and/or graft functional groups. In this work, we developed a novel radial non-thermal plasma injector that can be added to our ICP reactor for the in-flight synthesis and coating of nano silicon with carbon. Here, we show that ICP produces nano silicon particles which is then coated by an organic carbon layer in-flight by the NTP injector using an Ar/C2H6 gas mixture. To evaluate the success of the injector, the phase composition was evaluated using x-ray diffraction (XRD), the morphology and particle size was confirmed using scanning electron microscopy (SEM) and the chemical composition was validated using energy dispersive X-ray analysis (EDX). The novel NTP injector developed in this work coupled with ICP provides an efficient pathway for the synthesis of core-shell anodes necessary for further battery development.

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Amelkovich, Yuliya A., and Olga B. Nazarenko. "Production of Precursors for Ceramics Materials on the Base of Aluminum Nanopowders in Mixtures with Some Simple Substances." Advanced Materials Research 872 (December 2013): 70–73. http://dx.doi.org/10.4028/www.scientific.net/amr.872.70.

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Chemical activity parameters for aluminum nanopowder in mixtures with zinc, graphite, silicon, iron and copper powders are explored. The study of the phase content of combustion products shows that these mixtures can be used to produce precursors for ceramic materials.

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Blechta, Václav, Martin Mergl, Karolina Drogowska, Václav Valeš, and Martin Kalbáč. "NO2 sensor with a graphite nanopowder working electrode." Sensors and Actuators B: Chemical 226 (April 2016): 299–304. http://dx.doi.org/10.1016/j.snb.2015.11.130.

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Blagoveshchenskiy, Yu V., N. V. Isaeva, E. A. Lantsev, et al. "Spark plasma sintering of WC – 10 Co nanopowders with various carbon content obtained by plasma-chemical method." Perspektivnye Materialy, no. 8 (2020): 73–86. http://dx.doi.org/10.30791/1028-978x-2020-8-73-86.

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The features of high-speed sintering of WC – Co nanopowders with various contents of excess carbon (colloidal graphite) were studied. To obtain powders, a process was used that included plasma-chemical and low-temperature syntheses and a chemical-metallurgical method of applying ultrathin cobalt layers by precipitation from a solution of salts. The consolidation of powder materials was carried out by the method of high-speed Spark Plasma Sintering. It was found that an increase in the concentration of free carbon (colloidal graphite) has the greatest effect on the shrinkage and sintering rate at the stage of intense shrinkage of WC-Co nanopowders. It is shown that an increase in the carbon content in the composition of nanopowders leads to a decrease in the value of sintering activation energy at the stage of intense shrinkage.It has been established that the process of nanopowder compaction at the intense shrinkage stage is determined by the intensity of the plastic flow and the grain boundary diffusion of cobalt. It is shown that the mechanism of plastic deformation of the γ-phase based on cobalt corresponds to the Coble diffusion creep. It was found that an increase in carbon content leads to decreased in activation energy at the intense shrinkage and does not significantly affect at stage III of sintering where decrease in the shrinkage intensity is observed. It was shown that a decrease in the sintering activation energy is due to a decrease in the tungsten concentration in the γ-phase.

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Duda, P., R. Muzyka, Z. Robak, and S. Kaptacz. "Mechanical Properties of Graphene Oxide–Copper Composites." Archives of Metallurgy and Materials 61, no. 2 (2016): 863–68. http://dx.doi.org/10.1515/amm-2016-0146.

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Abstract Due to their characteristics, sintered Cu-C composites are materials used in electrical equipment. These characteristics include high electrical conductivity, thermal conductivity and excellent resistance to abrasion. Currently, graphite nanopowder is used successfully as a carbon material. Metal-graphite, which is created on its basis, exists in different proportions of graphite to metal. A larger graphite content has a positive effect on smaller wear of commutators and rings. In contrast, a material with a higher copper content is used at high current densities. An example of such machines is a DC motor starter characterized by low voltage and large current. Tribological properties of Cu-C composites depend on the form of carbon they include. Owing to the capability to manufacture graphene, it has become possible to produce composites with its content. The present study tested the effect of a graphene oxide content on tribological properties in contact with steel. Tests were conducted on a ball-on-disk apparatus in conditions of dry friction. Microscopic observation was performed on the Hitachi SU70 field emission electron microscope. EDS analyses were performed using the Thermo Scientific X-ray Microanalysis system. Disk wear and surface geometrical structure parameters (SGP) of the samples after tribological tests were determined on the basis of measurements made on the Talysurf 3D contact profilometer from Taylor Hobson.

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Khairunnisa, Amreen, and Senthil Kumar Annamalai. "Graphite nanopowder chemically modified electrode for hydrogen peroxide sensing." Journal of Indian Chemical Society Vol. 92, Apr 2015 (2015): 478–80. https://doi.org/10.5281/zenodo.5595731.

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Environmental and Analytical Chemistry Division, School of Advanced Sciences, Vellore Institute of Technology University, Vellore-632 014, Tamilnadu, India E-mail : askumarchem@yahoo.com Chemically modified electrodes (CMEs) are the recent impeccable achievements of electrochemists. The point lies in making simpler CMEs without any complicated methods of preparations. Here in, we present a graphite nanopowder (GNP) coated glassy carbon electrode (GCE), designated as GCE/GNP, for simple electrochemical sensing of H2O2 in pH 7 phosphate buffer solution. Note that H2O2 is extensively used in cosmetics and food products (as preservative in milk) and if the usable concentration exceeds certain limit then it may lead to severe health hazards. Thus, simple and low cost detection methodologies are most needed for the real sample analysis. Meanwhile, carbon nanomaterial have attracted great interest among researchers due to their unique structures, good electrical, mechanical, and chemical properties. GNP is one of such carbon nanomaterial which is very cheap and easy available in market. Here in we report a GCE/GNP modified electrode, without any enzyme and addition redox mediator, as a sensor for H2O2 . CV of the GCE/GNP showed a H2O2 -reduction peak at –0.5 V vs Ag/AgCl in pH 7 phosphate buffer solution. Control experiments with activated charcoal modified and unmodified glassy carbon electrodes failed to show any such marked H2O2 reduction signal. Furthermore, GCE/GNP was subjected to amperometric i–t curve technique which gave significant response to H2O2 -sensing. Biochemicals like cysteine, ascorbic acid, uric acid, dopamine and nitrate were also tested for interference.

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Khartaeva, Е. Ch, А. V. Nomoev, S. P. Bardakhanov, et al. "Experiments to Improve the Efficiency of Obtaining Brass Nanoparticles by Evaporation by a Continuous Beam of High-Energy Electrons." SIBERIAN JOURNAL OF PHYSICS 18, no. 3 (2024): 83–94. http://dx.doi.org/10.25205/2541-9447-2023-18-3-83-94.

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Composite, copper and zinc containing nanoparticles and brass nanoparticles have been obtained by a high-performance method of evaporation of substances by a relativistic electron beam. The change in the stoichiometry of nanopowders produced by stepwise irradiation of a brass ingot placed in a single-zone graphite crucible is considered. It was found that the production of such particles depends on the concentration of saturated vapors of zinc and copper. A two-zone configuration of the crucible has been developed, which makes it possible to realize the simultaneous evaporation of the constituent components, thereby providing the conditions for the formation of uniform brass nanoparticles with a uniform distribution of elements and a high yield of nanopowder. X-ray diffraction analysis (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDX) were carried out, and the specific surface of the obtained nanoparticles was determined. The mechanism of formation of composite nanoparticles is discussed.

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MUZYKA, Roksana, Piotr DUDA, Zbigniew ROBAK, Sławomir KAPTACZ, and Sabina DREWNIAK. "TRIBOLOGICAL PROPERTIES OF GRAPHENE OXIDE-METAL-CARBON COMPOSITES." Tribologia 281, no. 5 (2018): 53–64. http://dx.doi.org/10.5604/01.3001.0012.7654.

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Cu-C composites are materials used for the production of brushes, contacts, and pressing shoes for electric machines due to their mechanical and wear properties. These characteristics include good thermal and electrical conductivity, a low coefficient of friction, and lubricity under varying operating conditions. Currently, graphite and copper nanopowder based materials are used as a metal-carbon material in different ratios of these components. Graphite content in this kind of material has a positive effect on the smaller consumption of, e.g., rings and commutators. In contrast, a material without graphite content is used at high current densities. The examples of such machines are a DC motor starter or generators for electrolysis characterized by large current and low voltage. The present study tested the effect of graphene oxide (rGO) content on tribological properties in contact with steel in Cu-C composites. Tests were conducted on a ball-on-disk apparatus in conditions of dry friction. Disk wear and surface geometrical structure parameters (SGP) of the samples after tribological tests were determined on the basis of measurements made on the Talysurf.3D contact profilometer from Taylor Hobson. Damage mechanisms were identified and their relationships with structural characteristics were deducted. The hardness of Cu-C materials was higher than in copper. Cu-C based materials produce a better improvement of wear resistance, while the wear resistance of the graphene oxide based composites also decreased.

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Nayak, Manoj Kumar, M. Mubashir Bhatti, Oluwole Daniel Makinde, and Noreen Sher Akbar. "Transient Magneto-Squeezing Flow of NaCl-CNP Nanofluid over a Sensor Surface Inspired by Temperature Dependent Viscosity." Defect and Diffusion Forum 387 (September 2018): 600–614. http://dx.doi.org/10.4028/www.scientific.net/ddf.387.600.

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Present study is to a great extent explains the time dependent squeezing magneto-hydrodynamic flow of Sodium Cloride-Carbon nanopowder nanofluid past a sensor surface. The current study is all about the influence of temperature dependent viscosity represented by Reynolds model and Vogel’s model on the MHD flow of the nanofluid considered. Successive Taylor series linearization method has been implemented in order to obtain the numerical solution of the transformed non-linear governing equations. It is very important to mention that irrespective of whether it is NaCl-Graphite or NaCl-Carbon Black or NaCl-Carbon nanopowder, the presence of magnetic field strength contributes the impede movement of the fluid while enhancement in the volume fraction, Reynolds model and Vogel’s model viscosity parameters exhibit the diametrically opposite trend. Keywords: NaCl-CNP nanofluid; MHD; Variable viscosity; Unsteady Squeeze flow; Sensor surface.

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Zhang, Xian, Lai Fei Cheng, Li Tong Zhang, Shou Jun Wu, and Yong Dong Xu. "Effect of Yttria Nanopowder on Multi-Layer Coatings of Yttria And CVD SiC/Graphite." Key Engineering Materials 334-335 (March 2007): 653–56. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.653.

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Nano-yttria powder can be synthesized by yttrium citrate-urea precursor, combusted at 600°C in air. The CVD SiC coated on graphite (CVD SiC/Graphite) infiltrated by the yttrium citrate-urea precursor, combusted at of 600°C, and then sintered at 1450°C, the thin yttria film can be achieved. The SEM morphology and EDS result of the thin yttria film show a mass of needle-shaped pining into the CVD SiC layer, which improves the combination of CVD SiC layer and wash yttria coating. Therefore, it is an effective transition layer between CVD SiC coating and wash yttria layer.

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Saad, M., A. G. Kiiamov, S. I. Nikitin, D. A. Tayurskii, and R. V. Yusupov. "Ferromagnetism of the graphite nanopowders with cobalt oxide impurity and its evolution under mild annealing." Materials Science, no. 6 (2022): 3–8. http://dx.doi.org/10.31044/1684-579x-2022-0-6-3-8.

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In the paper, the influence of a small impurity of the cobalt oxide CoO on the magnetic properties of the graphite nanopowder is studied. It is shown that such an impurity causes a weak ferromagnetism of the as-prepared and annealed in the air at 670 K samples which significantly increases after an annealing in vacuum. Exchange bias effect is observed that originates from the partial reduction of the antiferromagnetic CoO particles to the ferromagnetic metallic state.

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Ben Mansour, N., G. Khouqeer, N. Abdel All, and J. El Ghoul. "Synthesis of hybrid nanocomposites by sol-gel method and their characterizations." Journal of Ovonic Research 18, no. 1 (2022): 57–65. http://dx.doi.org/10.15251/jor.2022.181.57.

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In this work, we report the synthesis of different hybrid nanocomposites by sol-gel method. Therefore, we used picric acid as a catalyst to incorporate the nanopowder oxides of nickel (NiO), copper (CuO) and manganese (MnO) in the porous carbon matrix based on pyrogallol and formaldehyde (PF). After a drying and heat treatment for two hours at 650 °C pyrolysis temperature, the obtained materials have been characterized by different structural and electrical techniques. The X-ray diffraction (XRD) spectra show that the incorporation of inorganic nanoparticles improved the crystallization of different nanocomposites with the existance of a graphite phase. The transmission electron microscopy (TEM) images reveal that the graphite nanoparticles size depends to the incorporated inorganic oxide. From the electrical studies, we notice that electrical conduction is linked to the presence of graphite nanoparticles. The variation of the electrical conductivity and the relaxation time with the measurement temperature, ranging between 80 and 300 K, explain the effect of the hopping conduction mechanism in these nanocomposites.

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Ciobanu, Mariana, Claudiu Nicolicescu, Simona Bejan, Gabriel Batin, and Ionel Mercioniu. "Studies Concerning the Microhardness of Sintered Carbon Steels Obtained from Fe and Fe₃C Nanopowders." Materials Science Forum 672 (January 2011): 223–28. http://dx.doi.org/10.4028/www.scientific.net/msf.672.223.

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Replacing the graphite with carbides in the mixture with Fe powder may be an alternative technological process, by the fact that as carbides decompose when heated, the carbon is set free and diffuses into the Fe network ensuring chemical and structural homogeneity corresponding to sintered steels. Using cementite nanopowder mix with Fe powder is to ensure a better compaction by pressing, less time to decompose and C diffusion into the Fe network in a remarkably chemical homogeneity. The obtaining procedure for Fe3C consists in direct carburation of Fe powder in a special chamber.

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Lantsev, E. A., A. V. Nokhrin, M. S. Boldin, et al. "Spark Plasma Sintering of ultrafine-grained WC – Al2O3 ceramics." Perspektivnye Materialy 4 (2023): 76–88. http://dx.doi.org/10.30791/1028-978x-2023-4-76-88.

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The sintering mechanisms of WC – Al2O3 nanopowder compositions with different contents of aluminum oxide particles (1, 3, 5 wt.%) were investigated. Samples of WC – Al2O3 ceramics were produced by Spark Plasma Sintering method (SPS) in vacuum, by heating to a temperature of 1450 °C at a rate of 50 °C/min under uniaxial stress 70 MPa. Plasma-chemical nanopowders of tungsten monocarbide and submicron powders of aluminum oxide were used to make the ceramics. The density, microstructure, phase composition, microhardness (Hv) and fracture toughness (KIC) of the ceramics were investigated. It was shown that the use of the SPS method makes it possible to obtain WC-Al2O3 ceramics with good relative density (95.4-98.1%) and a homogeneous microstructure with ultrafine grain size (0.1 – 0.2 μm). By the method of the X-ray phase analysis, it was established that in the process of SPS of WC-Al2O3 ceramics the formation of an undesirable W2C phase takes place, leading to decrease in the fracture toughness KIC. To reduce the intensity of W2C particle formation, colloidal graphite (0.1, 0.2, 0.3 wt.%) was added to WC – Al2O3 ceramics. Using the Young-Cutler model and the model of diffusion resorption of pores it was shown that the main mechanism of SPS of WC – Al2O3 ceramics is grain boundary diffusion. It is shown that the introduction of graphite leads to a decrease in the activation energy of SPS of WC – Al2O3 ceramics, which is probably due to a decrease in the W2C particle content to 0.5 wt.%.

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Chmielewski, Marcin, Katarzyna Pietrzak, Jan Dutkiewicz, Witold Piekoszewski, and Remigiusz Michalczewski. "Effect of Different Form of Carbon Addition on the Wear Behaviour of Copper Based Composites." Advances in Science and Technology 89 (October 2014): 31–36. http://dx.doi.org/10.4028/www.scientific.net/ast.89.31.

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Copper-carbon composites are very promising functional materials used as electrical contact devices due to their high electrical conductivity, thermal conductivity and excellent wear resistance. In the present study the influence of carbon forms (including carbon nanotubes, graphite nanopowder and graphene) on the properties of copper matrix composites was examined. The composites were fabricated using the powder metallurgy method. The optimal parameters of the hot-pressing process in vacuum were fixed as follows: the temperature of 525°C, the pressure of 600 MPa and the time of 10 min. The wear tests were performed in dry conditions using an SRV (Schwingungs Reibung und Verschleiss) friction and wear tester in a reciprocating motion. The friction and wear behaviour of copper with 3 vol.% of carbon were investigated. Scanning electron microscopy (SEM) was used to analyse the worn surfaces and debris, and finally the wear mechanism was discussed.

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KOROLEV, Albert V., Andrey A. KOROLEV, and Albina S. BONDAREVA. "INFLUENCE OF THE APPLYING MODE OF THE ANTIFRICTION COATING BY ULTRASONIC TREATMENT ON THE ROUGHNESS OF THE TREATED SURFACE." Mechanics of Machines, Mechanisms and Materials 1, no. 66 (2024): 43–49. http://dx.doi.org/10.46864/1995-0470-2024-1-66-43-49.

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The article presents an experimental study of the effect of the ultrasonic diamond smoothing mode on the surface roughness of the roller bearing roller end face in the presence of graphite nanopowder on the treated surface. In the presence of graphite nanopowder on the surface, the diamond smoothing process is accompanied by the formation of a solid antifriction coating on the treated surface, which can affect the formation of the microrelief of the treated surface. The design of an ultrasonic installation is described for diamond smoothing of the rollers end surface with the possibility of simultaneous application of a solid antifriction coating to this surface. The installation is assembled on the basis of a 16K20 screw-cutting machine. It consists of a device for installing rollers in the chuck of the lathe and an ultrasonic transducer mounted on the caliper of the machine. A diamond tip was used as a working tool in this device which was attached to the end of the oscillation concentrator of the ultrasonic transducer. Axle box bearing rollers of 36-42726E2M series (GOST 18855-94) were used as experimental samples. The subject of research was regression dependences of the influence of ultrasonic processing mode on the treated surface roughness. Full factorial experiment method was used to conduct the research. The tool tip rounding radius, tool transverse feed, specimen rotation speed, and tool pressure force on the machined surface of the specimen were used as varying factors. The power-law dependence of treatment indices on the adopted varying factors was taken as a mathematical model. It is shown that the greatest influence on the surface roughness is exerted by the tool transverse feed and the diamond tip rounding radius.

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Srikiran, S., P. N. L. Pavani, and Kumaran Palani. "Modeling of Nanolubricant-Assisted Machining Process by using Multiple Regression Analysis." Journal of Nanomaterials 2023 (February 14, 2023): 1–12. http://dx.doi.org/10.1155/2023/3669399.

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Graphite, due to its hexagonally arranged crystal structure, is a preferred lubricant. The crystal structure within a planar condensed ring system indicates that the layers are stacked in a direction that is parallel to each other. Researchers have reported that the use of graphite powder as a lubricant during machining has exhibited promising results. Mixture of graphite in a carrying medium demonstrated multifunctional lubrication performance due to the separation of sliding surfaces by a liquid lubricant film and protected by solid powder. Scientific literature has pointed out that graphite powder at the nanoscale has been used in various mechanical operations exhibiting promising results. It is found that nanolevel graphite powder has been used previously by researchers in the metal-forming operations and tribological tests. This emphasizes the significance of the present work, which investigates the impact of nanoscale differences in the particle size of graphite powder has on the machining of hardened steel. With SAE 40 oil functioning as the carrying medium and nanocrystalline graphite of various size range performing as the lubricant, the current work attempts to determine the effects of solid-lubricant-assisted machining. It is observed experimentally that the machining parameters have improved with respect to the particle size of the nanopowder. The experimental results show that the cutting forces, tool temperatures, and surface roughness are found to increase as the size of the nanocrystalline graphite powder is reduced from 70–90 to 5–10 nm. Using the experimental values, regression analysis is carried out to develop nonlinear expressions between the input and output variables using SPSS statistical tool. The data are used to develop the models to predict cutting forces, tool temperatures, and surface roughness for the input parameters like size of the nanocrystalline graphite powder, depth of cut, feed rate, and cutting velocity for a considerably good range in a scientific way so that further researchers can use it. Further, the outputs obtained from the experimentation and the regression equations are compared and analysis is carried out in terms of the error percentage.

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Sun, Yuning, Ki Nam Yun, Guillaume Leti, Sang Heon Lee, Yoon-Ho Song, and Cheol Jin Lee. "High-performance field emission of carbon nanotube paste emitters fabricated using graphite nanopowder filler." Nanotechnology 28, no. 6 (2017): 065201. http://dx.doi.org/10.1088/1361-6528/aa523e.

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Stefan-van Staden, Raluca-Ioana, and Oana-Raluca Musat. "Enantioanalysis of Leucine in Whole Blood Samples Using Enantioselective, Stochastic Sensors." Chemosensors 11, no. 5 (2023): 259. http://dx.doi.org/10.3390/chemosensors11050259.

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Enantioanalysis of amino acids became a key factor in the metabolomics of cancer. As a screening method, it can provide information about the state of health of patients. The main purpose of the study is to develop a highly reliable enantioanalysis method for the determination of D-, and L-leucine in biological samples in order to establish their role as biomarkers in the diagnosis of breast cancer. Two enantioselective stochastic sensors based on N-methyl-fullero-pyrrolidine in graphite and graphene nanopowder pastes were designed, characterized, and validated for the enantioanalysis of leucine in whole blood. Different signatures were recorded for the biomarkers when the stochastic sensors were used, proving their enantioselectivity. In addition, limits for detection on the order of ag L−1 were recorded for each of the enantiomers of leucine when the proposed enantioselective stochastic sensors were used. The wide linear concentration ranges facilitated the assay of the L-leucine in healthy volunteers, and also in patients confirmed with breast cancer. Recoveries of one enantiomer in the presence of the other enantiomer in whole blood samples, higher than 96.50%, proved that the enantioanalysis of enantiomers can be performed reliably from whole blood samples.

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Junin, Chabaiporn, Attera Worayingyong, Chanapa Kongmark, et al. "A Morphological Investigation of Ag/Graphite Oxide/TiO₂ Composites for Photocatalysis." Solid State Phenomena 302 (April 2020): 9–17. http://dx.doi.org/10.4028/www.scientific.net/ssp.302.9.

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To handle persistent toxic organic contaminants in water, advanced oxidation process (AOP) by titanium dioxide (TiO2) and its composites has been extensively utilized. A smart combination of composite materials was synthesized to improve photocatalytic activity of TiO2 via engineering effective charge transfer. In this study, synthesis of Ag/Graphite Oxide (GO)/TiO2 was investigated. Degussa P25 TiO2 (Rutile:Anatase of 85:15, 99.9%, 20nm) nanopowder was purchased. Graphite oxide was prepared using modified Hummer’s method. Photoreduction and ultrasonication were conducted to prepare Ag nanoparticles (AgNPs). XRD was used to confirm formation of Ag- GO- TiO2, i.e., peaks of GO, AgNPs and phases of anatase and rutile of TiO2 P25. Backscattered SEM was used to identify the AgNPs in different compositions of the AgNPs/GO/TiO2 composites. TEM was used for high resolution images to observe sizes and shapes of nanomaterials involved. X-ray absorption near edge structure (XANES) spectra of the Ag L3-edge were used to confirm zero-valence AgNPs. The best performed photocatalyst from this study was 5Ag0.5GOTiO2 with 78.86 % degradation of RhB after 2 hours. The AgNPs were found to be spherical with sizes of around 2-10 nanometers and evenly distributed within the GO/TiO2 matrix.

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Mukherjee, Priya, and Pichiah Saravanan. "Graphite nanopowder functionalized 3-D acrylamide polymeric anode for enhanced performance of microbial fuel cell." International Journal of Hydrogen Energy 45, no. 43 (2020): 23411–21. http://dx.doi.org/10.1016/j.ijhydene.2020.06.110.

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Piri, Somayyeh, Farideh Piri, Mohammad Reza Yaftian, and Abbasali Zamani. "Imprinted Azorubine electrochemical sensor based upon composition of MnO2 and 1-naphthylamine on graphite nanopowder." Journal of the Iranian Chemical Society 15, no. 12 (2018): 2713–20. http://dx.doi.org/10.1007/s13738-018-1459-z.

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SHEIBANI, S., A. ATAIE, and S. HESHMATI-MANESH. "FORMATION MECHANISM AND CHARACTERIZATION OF NANOCRYSTALLINE CU SYNTHESIZED BY MECHANO-CHEMICAL METHOD." International Journal of Modern Physics B 22, no. 18n19 (2008): 2962–69. http://dx.doi.org/10.1142/s021797920804781x.

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Nanocrystalline Cu particles were prepared by mechanochemical reduction of cuprite ( CU 2 O ) with graphite in a high-energy ball mill. In order to gain an understanding into the possible mechanisms, the kinetic of the process was investigated using Johnson-Mehl-Avrami (JMA) model. It can be seen that theoretical calculation agrees well with experimental data. It was found that the most important effect of mechanical activation is the formation of the lattice defects and grain boundaries in addition to activated fresh surface areas during milling, which promote the reduction process. The Cu nanopowder was characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM results showed the nano-structure nature of the product processed under the synthesis conditions; the crystallite size was measured almost 30 nm in the 30 h milled powders.

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Torrinha, Álvaro, Thiago M. B. F. Oliveira, Francisco W. P. Ribeiro, Adriana N. Correia, Pedro Lima-Neto, and Simone Morais. "Application of Nanostructured Carbon-Based Electrochemical (Bio)Sensors for Screening of Emerging Pharmaceutical Pollutants in Waters and Aquatic Species: A Review." Nanomaterials 10, no. 7 (2020): 1268. http://dx.doi.org/10.3390/nano10071268.

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Pharmaceuticals, as a contaminant of emergent concern, are being released uncontrollably into the environment potentially causing hazardous effects to aquatic ecosystems and consequently to human health. In the absence of well-established monitoring programs, one can only imagine the full extent of this problem and so there is an urgent need for the development of extremely sensitive, portable, and low-cost devices to perform analysis. Carbon-based nanomaterials are the most used nanostructures in (bio)sensors construction attributed to their facile and well-characterized production methods, commercial availability, reduced cost, high chemical stability, and low toxicity. However, most importantly, their relatively good conductivity enabling appropriate electron transfer rates—as well as their high surface area yielding attachment and extraordinary loading capacity for biomolecules—have been relevant and desirable features, justifying the key role that they have been playing, and will continue to play, in electrochemical (bio)sensor development. The present review outlines the contribution of carbon nanomaterials (carbon nanotubes, graphene, fullerene, carbon nanofibers, carbon black, carbon nanopowder, biochar nanoparticles, and graphite oxide), used alone or combined with other (nano)materials, to the field of environmental (bio)sensing, and more specifically, to pharmaceutical pollutants analysis in waters and aquatic species. The main trends of this field of research are also addressed.

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Lee, Gyoung-Ja, Hi Min Lee, Young Rang Uhm, Min Ku Lee, and Chang-Kyu Rhee. "Square-wave voltammetric determination of thallium using surface modified thick-film graphite electrode with Bi nanopowder." Electrochemistry Communications 10, no. 12 (2008): 1920–23. http://dx.doi.org/10.1016/j.elecom.2008.10.015.

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Vishnu Chandar, J., S. Shanmugan, D. Mutharasu, M. Khairudin, and A. A. Azlan. "Polysiloxane-graphite composites as thermal interface material for light emitting diode application: a study on impact of graphite nanopowder on thermal and surface properties." Polymer-Plastics Technology and Materials 59, no. 1 (2019): 106–15. http://dx.doi.org/10.1080/25740881.2019.1625392.

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Jahan, M. P., M. M. Anwar, Y. S. Wong, and M. Rahman. "Nanofinishing of hard materials using micro-electrodischarge machining." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 223, no. 9 (2009): 1127–42. http://dx.doi.org/10.1243/09544054jem1470.

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Micro-electrodischarge machining (micro-EDM) has been found to be an effective method of machining all types of conductive material, regardless of hardness. The process is being widely used in the production of tools and dies using hard and difficult-to-cut materials, where the surface quality of the product is of prime importance. The purpose of the present study is to investigate the feasibility of achieving fine surface finish in the micro-EDM of hard tungsten carbide (WC) and tool steel (SKH-51). Three different approaches: sinking, milling, and powder mixed dielectric (PMD) micro-EDM were applied in order to obtain a fine surface finish. The surface characteristics of machined WC and SKH-51 were studied and compared based on the surface topography achieved, the average surface roughness ( Ra), and the peak-to-valley roughness ( Rmax) of the machined surface. It has been found that the topography and finish of the machined surface greatly depend on the discharge energy during machining. The surface generated using micro-EDM milling is found to be smoother and defect-free compared with those generated by die-sinking. At the same discharge energy, SKH-51 tool steel provides lower Ra and Rmax when compared with WC. Finally, graphite PMD has been applied in the micro-EDM of SKH-51, as it provides comparatively lower Ra and Rmax. It has been found that both the Ra and Rmax were significantly reduced and crater distribution became more uniform when graphite nanopowder mixed dielectric was applied. Among the approaches, PMD milling micro-EDM has been found to provide a relatively improved surface finish during machining SKH-51.

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Skury, Ana Lúcia Diegues, Guerold Sergueevitch Bobrovinitchii, Marcia G. de Azevedo, and Sérgio Neves Monteiro. "Use of Niobium Oxide as a Binder in the Production of Diamond Nanostructured Composites." Materials Science Forum 727-728 (August 2012): 924–28. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.924.

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The sintering of nanodiamond powders is of interest for both applied engineering of tool materials and fundamental materials science of nanodisperse covalent-type ceramic materials. It is a accept as a general notion that the driving force for sintering of monophase particles is determined by the level of the surface energy. In the case of diamond nanopowder, this level must be significantly higher which makes sintering a difficult process. This difficulty of sintering is connected with the low diffusive mobility of carbon causing the formation of a graphite structure onto surface of the diamond crystals. From this point of view the use of niobium oxide as a binder could be a solution. In an attempt to inhibit the diamonds graphitization process, Nb2O5 and small amounts of amorphous carbon were introduced in the reaction zone. Sintering process was conducted at 6.0 GPa of pressure and 1100-1400oC for a processing time of 30 seconds. At the end of the process, the samples were cleaned, and prepared to be characterized by X-ray diffraction, scanning electron microscopy, density and porosity. From these results it was proposed a densification mechanism based on the consolidation of the particle by diffusion and coalescence of clusters.

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Ratov, Boranbay, Volodymyr Mechnik, Miroslaw Rucki, et al. "Enhancement of the Refractory Matrix Diamond-Reinforced Cutting Tool Composite with Zirconia Nano-Additive." Materials 17, no. 12 (2024): 2852. http://dx.doi.org/10.3390/ma17122852.

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This paper presents the results of the experimental research on diamond-reinforced composites with WC–Co matrices enhanced with a ZrO2 additive. The samples were prepared using a modified spark plasma sintering method with a directly applied alternating current. The structure and performance of the basic composite 94 wt.%WC–6 wt.%Co was compared with the ones with ZrO2 added in proportions up to 10 wt.%. It was demonstrated that an increase in zirconia content contributed to the intense refinement of the phase components. The composite 25 wt.%Cdiamond–70.5 wt.%WC–4.5 wt.%Co consisted of a hexagonal WC phase with lattice parameters a = 0.2906 nm and c = 0.2837 nm, a cubic phase (a = 1.1112 nm), hexagonal graphite phase (a = 0.2464 nm, c = 0.6711 nm), as well as diamond grits. After the addition of zirconia nanopowder, the sintered composite contained structural WC and Co3W3C phases, amorphous carbon, tetragonal phase t-ZrO2 (a = 0.36019 nm, c = 0.5174 nm), and diamond grits—these structural changes, after an addition of 6 wt.% ZrO2 contributed to an increase in the fracture toughness by more than 20%, up to KIc = 16.9 ± 0.76 MPa·m0.5, with a negligible decrease in the hardness. Moreover, the composite exhibited an alteration of the destruction mechanism after the addition of zirconia, as well as enhanced forces holding the diamond grits in the matrix.

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Martyushev, N. V., and E. N. Pashkov. "Bronze Sealing Rings Defects and Ways of its Elimination." Applied Mechanics and Materials 379 (August 2013): 82–86. http://dx.doi.org/10.4028/www.scientific.net/amm.379.82.

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In the article data about application nanopowder on a structure of coatings of the form are submitted at a casting of lead-tin bronzes. Elimination of gas porosity on a surface bronze cast preparations of high pressure compressors piston rings was the primary goal of such application protectively-dividing coverings. For experimental works mark of multicomponent bronze has been chosen. Its structure includes tin, lead, zinc and nickel. Casting from this bronze received a method of centrifugal molding. Influence of a structure of used protective - separating coating of a foundry core on a surface smoothness was probeed. Was compared action of coatings of a following composition: anti-burning-in coating (a blend of a low dispersible powder of chromium oxide with calcinated vegetable oil); anti-burning-in material ASPF-2/RgU (on the basis a low dispersible powder of graphite and the calcinated vegetable oil); the patent № 2297300 (blend of a ultradispersible powder of dioxide of zirconium with inpowderrial oil. Molding without use of coverings leads porosity depth to 4-5 mm and to a marriage significant amount (to 50 %). Use ASPF-2/RgU completely eliminates welding casting to a casting mold, but porosity on a surface remains. Application of coverings of a casting mold containing in quality of a filler ultradisperse powders oxide metals with low heat conductivity allows in to lower much a roughness and to eliminate gas porosity on a cast surface from lead-tin bronze. A gas time of a surface still remains, but them becomes much less and their form changes. Depth of defects doesn't exceed 1-1,5 mm that doesn't fall outside the limits the admission.

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Ezdin, B. S., S. A. Vasiljev, D. A. Yatsenko, et al. "The Synthesis of Carbon Nanoparticles in a Compression Reactor in the Atmosphere of Buffer Gases." SIBERIAN JOURNAL OF PHYSICS 17, no. 3 (2022): 29–46. http://dx.doi.org/10.25205/2541-9447-2022-17-3-29-46.

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We investigated the physicochemical aspects of the gas-phase nanopowder synthesis using a cyclic compression reactor. Compression of precursors (methane, ethylene, acetylene) under conditions close to the adiabatic ones in the atmosphere of buffer monatomic gases (argon, helium, neon) was used. The influence of pressure in the reactor and volumetric ratio of precursor/buffer gas mixture on the composition, morphology, and structure of carbon-containing particles representing the pyrolysis product was studied. Complete pyrolysis was observed for all studied precursors, but under different conditions. Thermal decomposition of methane, having the minimum enthalpy of formation, was observed in an atmosphere with argon content 97.5 % at a peak pressure more than 10 MPa. Helium showed limited possibilities for thermal relaxation under the conditions of fast reactions (< 50 ms). Only acetylene with the maximum enthalpy of formation was decomposed in the atmosphere of helium. The solid reaction products represented black colored powders with a bulk density of 20–30 mg/cm3. The powders were examined by transmission electron microscopy and scanning electron microscopy, Raman scattering and X-ray diffraction analysis. The particles represent globular bulbous structures up to 100 nm in size, either hollow or filled inside. X-ray diffraction analysis showed the presence of a graphite-like structure with crystallite sizes less than 10 nm in all samples. Raman analysis showed mainly sp2 hybridization of carbon. The cyclic compression method demonstrates wide range of opportunities for the pyrolysis of hydrocarbons aiming at the production of a variety of carbon structures, which enables for the fine tuning in terms of the yield of products of the required morphology for practical use.

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Elias, Rasha R. "Investigation of the Effect of Nano Powder Mixed Dielectric on EDM Process." Engineering and Technology Journal 38, no. 3A (2020): 295–307. http://dx.doi.org/10.30684/etj.v38i3a.337.

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In this paper, Artificial Neural Network was adopted to predict the effect of current, the concentration of aluminum oxide (Al2O3) and graphite Nanopowders in dielectric fluid for the machining of Carbon steel 304 using Electrical Discharge Machining (EDM). The process variables were utilized to find their effect on Material Removal Rate (MRR), Surface Roughness (SR), and Tool Wear Rate (TWR). It was revealed from the experimental work that the addition of aluminum oxide and graphite Nanopowders into dielectric fluid maximizing MRR, minimized the SR and TWR at various variables. Minitab software was used in the design of experiments. Analysis of the process outputs of EDM indicates that graphite powder concentration greatly influencing SR also the discharge current whereas the current and Nanopowders concentration has more percentage of influence on the TWR and MRR.

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Priya, I. Infanta Mary, and BK Vinayagam. "Enhancement of bi-axial glass fibre reinforced polymer composite with graphene platelet nanopowder modifies epoxy resin." Advances in Mechanical Engineering 10, no. 8 (2018): 168781401879326. http://dx.doi.org/10.1177/1687814018793261.

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The material used for the study is bi-axial glass cloth with epoxy resin. Two sets of laminates were manufactured using vacuum assisted resin transfer moulding, one laminate with parent material (P1, P2) and the other laminate with graphene platelet nanopowder (P1-GPN, P2-GPN). For the graphene platelet nanopowder samples, addition of 0.1% weight of graphene platelet nanopowder is mixed with epoxy resin. Three different tests such as tensile, compression and impact were conducted on the composite material. There was an increase of 11.18% and 33.4% in tensile strength, 26.4% and 24.6% in compression strength when compared to the parent samples of 2 and 3 mm thickness, respectively. This strength was obtained with the reduction of fibre content when compared to other research works. Also high-velocity impact test using gas-gun method was performed on parent and blended samples. The energy absorption levels of blended samples were 9.2% and 8.2% higher than the parent samples of 2 and 3 mm thickness, respectively. Therefore, this study reveals that the addition of graphene platelet nanopowder with the parent material has increased the strength of the composite tremendously.

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Dizge, Nadir, Hakan Gonuldas, Yasin Ozay, et al. "Synthesis and performance of antifouling and self-cleaning polyethersulfone/graphene oxide composite membrane functionalized with photoactive semiconductor catalyst." Water Science and Technology 75, no. 3 (2016): 670–85. http://dx.doi.org/10.2166/wst.2016.543.

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This study was performed to synthesize membranes of polyethersulfone (PES) blended with graphene oxide (GO) and PES blended with GO functionalized with photoactive semiconductor catalyst (TiO2 and ZnO). The antifouling and self-cleaning properties of composite membranes were also investigated. The GO was prepared from natural graphite powder by oxidation method at low temperature. TiO2 and ZnO nanopowders were synthesized by anhydrous sol–gel method. The surface of TiO2 and ZnO nanopowders was modified by a surfactant (myristic acid) to obtain a homogeneously dispersed mixture in a solvent, and then GO was functionalized by loading with these metal oxide nanopowders. The PES membranes blended with GO and functionalized GO into the casting solution were prepared via phase inversion method and tested for their antifouling as well as self-cleaning properties. The composite membranes were synthesized as 14%wt. of PES polymer with three different concentrations (0.5, 1.0, and 2.0%wt.) of GO, GO-TiO2, and GO-ZnO. The functionalization of membranes improved hydrophilicity property of membranes as compared to neat PES membrane. However, the lowest flux was obtained by functionalized membranes with GO-TiO2. The results showed that functionalized membranes demonstrated better self-cleaning property than neat PES membrane. Moreover, the flux recovery rate of functionalized membranes over five cycles was higher than that of neat membrane.

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Lantsev, Е. А., N. V. Malekhonova, V. N. Chuvil’deev, et al. "Study of high-speed sintering of fine-grained hard alloys based on tungsten carbide with ultralow cobalt content. III. Effect of C content on sintering kinetics of the nanopowders." Physics and Chemistry of Materials Treatment 2 (2022): 35–54. http://dx.doi.org/10.30791/0015-3214-2022-2-35-54.

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The features of high-speed spark plasma sintering (SPS) of plasma-chemical nanopowders WC – (0.3, 0.6, 1) wt. % Co with the addition of 0.3 and 0.5 wt. % graphite were studied. The structural features of the ultralow-cobalt hard alloys with graphite addition during SPS are due to the simultaneous influence of an increased concentration of oxygen adsorbed on the surface of plasma-chemical WC – Co nanoparticles during mixing with graphite, and the effect of graphite, which leads to a decrease in activation energy of sintering due to a decrease in the intensity of formation of η-phase particles in “oxidized” WC – Co nanopowders, as well as the formation of a fairly uniform fine-grained structure. Samples of fine-grained ultralow-cobalt hard alloys with increased hardness and fracture toughness were obtained (for a WC – 0.6 wt. % Co – 0.3 wt. % C hard alloy with an average grain size of ~ (1 – 1.5) mm, the hardness is Hv = 20.2 – 20.5 GPa with a minimum crack resistance coefficient KIC = 9.2 – 10.4 MPa·m1/2).

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Ospanov, Yerlan Kanatovich, Gulzhan Abdullaevna Kudaikulova, Murat Smanovich Moldabekov, and Moldir Zhumabaevna Zhaksylykova. "Improving Shale Stability through the Utilization of Graphene Nanopowder and Modified Polymer-Based Silica Nanocomposite in Water-Based Drilling Fluids." Processes 12, no. 8 (2024): 1676. http://dx.doi.org/10.3390/pr12081676.

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Shale formations present significant challenges to traditional drilling fluids due to fluid infiltration, cuttings dispersion, and shale swelling, which can destabilize the wellbore. While oil-based drilling fluids (OBM) effectively address these concerns about their environmental impact, their cost limits their widespread use. Recently, nanomaterials (NPs) have emerged as a promising approach in drilling fluid technology, offering an innovative solution to improve the efficiency of water-based drilling fluids (WBDFs) in shale operations. This study evaluates the potential of utilizing modified silica nanocomposite and graphene nanopowder to formulate a nanoparticle-enhanced water-based drilling fluid (NP-WBDF). The main objective is to investigate the impact of these nanoparticle additives on the flow characteristics, filtration efficiency, and inhibition properties of the NP-WBDF. In this research, a silica nanocomposite was successfully synthesized using emulsion polymerization and analyzed using FTIR, PSD, and TEM techniques. Results showed that the silica nanocomposite exhibited a unimodal particle size distribution ranging from 38 nm to 164 nm, with an average particle size of approximately 72 nm. Shale samples before and after interaction with the graphene nanopowder WBDF and the silica nanocomposite WBDF were analyzed using scanning electron microscopy (SEM). The NP-WBM underwent evaluation through API filtration tests (LTLP), high-temperature/high-pressure (HTHP) filtration tests, and rheological measurements conducted with a conventional viscometer. Experimental results showed that the silica nanocomposite and the graphene nanopowder effectively bridged and sealed shale pore throats, demonstrating superior inhibition performance compared to conventional WBDF. Post adsorption, the shale surface exhibited increased hydrophobicity, contributing to enhanced stability. Overall, the silica nanocomposite and the graphene nanopowder positively impacted rheological performance and provided favorable filtration control in water-based drilling fluids.

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Cabaleiro, David, Samah Hamze, Jacek Fal, Marco A. Marcos, Patrice Estellé, and Gaweł Żyła. "Thermal and Physical Characterization of PEG Phase Change Materials Enhanced by Carbon-Based Nanoparticles." Nanomaterials 10, no. 6 (2020): 1168. http://dx.doi.org/10.3390/nano10061168.

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This paper presents the preparation and thermal/physical characterization of phase change materials (PCMs) based on poly(ethylene glycol) 400 g·mol−1 and nano-enhanced by either carbon black (CB), a raw graphite/diamond nanomixture (G/D-r), a purified graphite/diamond nanomixture (G/D-p) or nano-Diamond nanopowders with purity grades of 87% or 97% (nD87 and nD97, respectively). Differential scanning calorimetry and oscillatory rheology experiments were used to provide an insight into the thermal and mechanical changes taking place during solid-liquid phase transitions of the carbon-based suspensions. PEG400-based samples loaded with 1.0 wt.% of raw graphite/diamond nanomixture (G/D-r) exhibited the lowest sub-cooling effect (with a reduction of ~2 K regarding neat PEG400). The influences that the type of carbon-based nanoadditive and nanoparticle loading (0.50 and 1.0 wt.%) have on dynamic viscosity, thermal conductivity, density and surface tension were also investigated in the temperature range from 288 to 318 K. Non-linear rheological experiments showed that all dispersions exhibited a non-Newtonian pseudo-plastic behavior, which was more noticeable in the case of carbon black nanofluids at low shear rates. The highest enhancements in thermal conductivity were observed for graphite/diamond nanomixtures (3.3–3.6%), while nano-diamond suspensions showed the largest modifications in density (0.64–0.66%). Reductions in surface tension were measured for the two nano-diamond nanopowders (nD87 and nD97), while slight increases (within experimental uncertainties) were observed for dispersions prepared using the other three carbon-based nanopowders. Finally, a good agreement was observed between the experimental surface tension measurements performed using a Du Noüy ring tensiometer and a drop-shape analyzer.

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Khartaeva, Erzhena C., S. P. Bardakhanov, Andrey V. Nomoev, Konstantin V. Zobov, and Dmitriy Yur'yevich Trufanov. "Nanopowders Created by Irradiating Brass with Relativistic Electrons." Materials Science Forum 1083 (April 6, 2023): 61–69. http://dx.doi.org/10.4028/p-0j5bz6.

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The paper deals with changes in the stoichiometry of nanopowders obtained under staged irradiation of a brass ingot placed in a graphite crucible. Composite core-shell CuO/ZnO nanoparticles, copper nanoparticles, and copper and zinc oxides were obtained. The use of a relativistic electron accelerator is necessary to produce nanopowders on an industrial scale. Transmission electron microscopy and energy-dispersive analysis of the obtained nanoparticles were carried out. Thermodynamic calculation of the temperature dependence of the equilibrium content of copper and zinc is presented for the condensed and gas phases. The formation mechanism of CuO/ZnO composite nanoparticles is discussed.

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Sirajunisha, H., A. Krishnaveni, D. Sellathamil Selvaraj, and T. Balakrishnan. "Cationic and Anionic Substitutions in the Antibacterial and Biocompatibility Properties of Sol-Gel Derived Hydroxyapatite Nanocomposites." Journal of Scientific Research 66, no. 05 (2022): 103–19. http://dx.doi.org/10.37398/jsr.2022.660514.

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This paper deals the synthesis and characterization of Pure Hydroxyapatite (Pure HAp) nanopowderan its nanocomposites. Hydroxyapatite - Zinc (HAp-Zn), Hydroxyapatite - Manganese (HAp-Mn) Hydroxyapatite - Titanium (HAp-Ti) and Hydroxyapatite - reduced Graphene oxide (HAp-rGO). The impact of Zn, Mn, Ti and rGO on the underlying, morphological, antimicrobial property and biocompatibility of hydroxyapatite nanopowders are contemplated. The structural characterization analysed through XRD. Pure HAp, HAp-Ti and HAp-rGO displayed hexagonal structure and fuse of Zn and Mn in the host lattice changed the construction into orthorhombic and rhombohedral. The normal crystallite size goes from 51 nm to 37 nm for different nanocomposites. The consolidation of cations (Zn2+ Mn2+ and Ti4+) and anion (CO3 2- ) diminished the crystallite size. Blended nanocomposites has hexagonal construction though there is hexagonal to orthorhombic progress in HAp-Zn and hexagonal to rhombohedral change in HAp-Mn nanocomposites The presence of functional groups in the samples is investigated utilizing FTIR examination. Surface morphology and compound organizations are examined utilizing Scanning Electron Microscope (SEM) and Energy Dispersive X-beam investigation (EDX) individually. The in-vitro antibacterial exercises and biocompatibility of the combined hydroxyapatite and its nanocomposite are examined utilizing Kirby-Bauer antibacterial testing and MTT assay individually. The outcomes show that Titanium and reduced Graphene Oxide fused hydroxyaptite nanocomposites are more harmful against every bacterial strain and didn't show any harmfulness against living tissues.

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Majchrzycki, Łukasz, Monika Michalska, Mariusz Walkowiak, Zbigniew Wiliński, and Ludwika Lipińska. "Graphene oxide-assisted synthesis of LiMn2O4 nanopowder." Polish Journal of Chemical Technology 15, no. 3 (2013): 15–19. http://dx.doi.org/10.2478/pjct-2013-0038.

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Abstract The article reports sol-gel synthesis of nanosized spinel-type lithium manganese oxide LiMn2O4 (LMO) carried out in the presence of graphene oxide (GO) and its electrochemical lithium insertion ability. The synthesis was performed in an aqueous environment with lithium acetate and manganese acetate used as precursors and citric acid as a chelating agent. The material was characterized by X-ray diffraction, SEM microscopy, Raman spectroscopy and cyclic voltammetry. The calcination step totally eliminated graphene from the final product, nevertheless its presence during the synthesis was found to affect the resulting LiMn2O4 morphology by markedly reducing the size of grains. Moreover, potentials of electrochemical lithium insertion/deinsertion reactions have been shifted, as observed in the cyclic voltammetry measurements. Along with the diminished grain size the voltammetric curves of the graphene oxide-modified material exhibit higher oxidation and lower reduction peak currents. The study demonstrates that GO mediation/assistance during the sol-gel synthesis fosters more nanostructured powder and changes the electrochemical characteristics of the product

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Jang, Dawoon, Jung-Hyun Kim, and Sungjin Park. "Graphene Supported Silicon Nanocomposites As Anode for Lithium-Ion Batteries." ECS Meeting Abstracts MA2024-01, no. 7 (2024): 803. http://dx.doi.org/10.1149/ma2024-017803mtgabs.

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This work indicates Silicon/Grphene (Si/G) nanocomposites anode on the performance in lithium-ion batteries (LIBs). The self-assembled graphene aerogel and silicon (Si/G) anode materials with some surface defects have been successfully prpared by hydrothermal synthesis using chemically modified graphene oxide and commercial Si nanopowder (about 50 nm) as precursor. The morphologies and textural properties of as-obtained Si/G were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, and other sturucture techniques. The surface defects and electrical conductivities of Si/G can be controlled by adjusting the amount of Si nanopowder. The results indicate that Si/G with Si amount of half exhibits excellent stability and reversible capacity and superior rate capability with excellent cycling stability. It is demonstrated that the 3D porous network with increased defect density, as well as the considerable electrical conductivity, results in the excellent electrochemical performance of the as-made Si/G anodes in LIBs.

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Prasanthi, P. Phani, K. Sivaji Babu, M. S. R. Niranjan Kumar, and A. Eswar Kumar. "Comparison of elastic properties of different shaped particle reinforced composites using micromechanics and finite element method." International Journal of Computational Materials Science and Engineering 09, no. 02 (2020): 2050011. http://dx.doi.org/10.1142/s2047684120500116.

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In this work, differently shaped carbon nano-sized allotropes reinforced composite properties are estimated and interfacial stresses are calculated and compared to get the best carbon reinforcement. Carbon nanopowder, carbon nanotubes, nanographene and Buckminster fullerenes are selected as these materials have different shapes and reinforcement of these materials in the aluminium matrix will give different properties. The comparative studies are performed by using the Micromechanics and Finite element method. The longitudinal, transverse modulus, Poisson’s ratio are estimated along with the interface stresses between the constituents of carbon power/Al matrix composite, fullerene/Al matrix composite, CNT/Al matrix composite and graphene/Al matrix composite. From this work, it is found that the longitudinal modulus of the composite will be higher by using CNT or Graphene reinforcement and carbon particle or Buckminster fullerene reinforcement will give high transverse modulus than CNT and graphene reinforcement. The interfacial stresses generated between the reinforcement and the Aluminum matrix will be less by using carbon nanopowder than the other allotropes consider for the studies. This work will give an idea of the selection of nanoreinforcement of composite material in the perspective of elastic properties and interfacial stresses.

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Yin, Zheng E., He Zhang, Yan Ru Kang, Jian Min Feng, and Ya Li Li. "Fabrication of Graphene/Zirconia Nanocomposite by Mixing Graphite Oxide and Zirconia Nanopowders and Pressureless Sintering." Key Engineering Materials 512-515 (June 2012): 65–68. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.65.

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Graphene has unique two-dimensional nanostructure with high specific surface areas, superior mechanical properties which has promising applications for the development of high performance nanocomposite materials. Most of previous work on graphene nanocomposites addresses on polymer matrix. In the present work, we have fabricated zirconia and graphene nanocomposites (ZrO2/GNS) by simple mechanical mixing and pressureless sintering process. Microstructural observations of the composite show the homogeneous and random distributions of graphene nanosheet in the zirconia matrix. Scanning electronic microscopy observes partially pulled out graphene nanosheets with well combined interface with the matrix in fractural surface, showing promising reinforcement effects.

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