Papers by Keyword: Nanostructured Materials

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Authors: Nariman A. Enikeev, T.S. Orlova, Igor V. Alexandrov, A.E. Romanov
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Authors: Jin Sun, Qing Zhong Xue, Yong Gang Du, Fu Jun Xia, Qi Kai Guo
Abstract: Porous graphene is a collection of graphene-related materials which exhibits properties distinct from those of graphene, and it has widespread potential applications in various fields. Several approaches have been developed to produce porous graphene. However, the large-scale production of porous graphene nanosheets still remains a great challenge. Moreover, the costs of some methods are prohibitive for its commercial production and the processes are too complicated and time-consuming. In this work, we propose a simple and green method by which graphene nanosheets can be etched by sodium hydroxide under autogenous pressure at 180 °C. The morphologies and surface elements of the porous graphene nanosheets and sizes of pores were characterized. It is demonstrated that the one-step etching of graphene nanosheets is an effective method to obtain large-scale porous graphene nanosheets with high and uniform porosity. The pores in the porous graphene nanosheets were 6 nm depth (the same as the thickness of the graphene nanosheets) and 30-50 nm width.
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Authors: Dario Vallauri, Isabel M. Martins, Fabio A. Deorsola, Ignazio Amato, Francisco Delmas, Manuela Oliveira
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Authors: Radik R. Mulyukov, Ayrat A. Nazarov, Renat M. Imayev
Abstract: Deformation methods of nanostructuring (DMNs) of materials are proposed to classify into severe plastic deformation (SPD) and mild plastic deformation (MPD) methods according to fundamentally different low- and high-temperature grain refinement mechanisms they exploit. A general analysis of the fundamentals and nanostructuring efficiency of three most developed DMNs, high pressure torsion (HPT), equal-channel angular pressing (ECAP), and multiple isothermal forging (MIF) is done with a particular attention to ECAP and MIF. It is demonstrated that MIF is the most efficient method of DMNs allowing one to obtain the bulkiest nanostructured samples with enhanced mechanical properties.
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Authors: Marcin Kwapisz
Abstract: The paper presents the results of numerical simulations of the alternate indirect extrusion and multiaxial compression process, performed using commercial software designed for the thermomechanical analysis of plastic working processes, Forge 2009. The paper presents selected results on the distribution of deformation in the process of alternating extrusion and multiaxial compression. Examples of modifications to the shape of the die and punch, and their effect on the kinetics of the material flow as well as the likelihood of defects of materials are provided. The results confirm that suitable modifying the shape of the die and punch enables to obtain a material with no internal defects. Iterative process, alternating squeezing and multiaxial compressive strain allows the accumulation of which results in fragmentation of the microstructure.
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Authors: Viktor Varyukhin, Yan Beygelzimer, Sergey Synkov, Dmitry Orlov
Abstract: Twist Extrusion (TE) is a process of severe plastic deformation (SPD) being developed by us during recent 5 years. Upon this time we published few papers on mechanics of the process and influence of the TE processing on materials structure and properties. Here we reported some results on application of the twist extrusion processing and made few general conclusions.
335
Authors: Kai Feng Zhang, Hui Zhou, Rui Peng Sang, Zhi Hua Wan, Han Jun Hu
Abstract: With an extended service life expectancy of space crafts, fluid lubricants attracted intense interests of the fields of tribology, due to their long life under EDH conditions, higher thermal conductance, lower frictional and torque noise, and rapid processing compared to the solid lubricants. However, there are still some disadvantages of fluid lubricants, such as finite vapor pressure, narrow range of operating temperature, degradation of some oils, viscosity temperature-dependence and so on. So far, there have existed some space fluid lubricants, such as PFPE, MAC, PAO and mineral oil based lubricants. It seems that there will be a challenge for a new type of fluid lubricants to come out without any limits above. Recent arisen nanostructured materials assisted in improvement of the research of space fluid lubricants, and the results indicated that some nanostructured materials exactly promoted the tribological properties of fluid lubricants. This paper reviewed recent development of nanostructured materials as additives in space fluid lubricants.
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Authors: M.A. Alvarez-Pérez, M. García-Hipolito, J. de La Fuente Hernández, H. Arzate, B. Carmona-Rodriguez, L.A. Ximenez-Fyvie, J.A. Juarez-Islas, O. Alvarez-Fregoso
Abstract: We have used zinc aluminate nanostructured films deposited by spray pyrolysis to determine its biocompatibility assessed by cells attachment and cell differentiation. Cell attachment onto zinc aluminate showed an increase of 53, 81 and 86% at 180, 300 and 420 minutes (p<0.05) when compared to controls. Mineralization was analyzed at 5 and 14 days of culture by scanning electron microscopy, microanalysis and atomic force microscopy. Our results showed in experimental culture a higher density of mineral-like tissue with small needle-shaped crystal and granular nanoparticles with preferential orientation when compared to controls. The composition of the mineral-like tissue deposited in zinc aluminate nanostructured material had a Ca/P ratio of 1.6, whereas control culture had a Ca/P ratio of 1.50. Our finding revealed that ZnAl2O4 promoted higher expression of type I collagen, bone sialoprotein, osteocalcin and alkaline phosphatase, suggesting that zinc aluminate provides a microenvironment that favors mineral formation and cell differentiation. Our results point to the potential use of ZnAl2O4 for the osteoinductive process in biomedical implants.
169
Authors: Mohammadjavad Mahdavinejad, Leili Hashemi Rafsanjani, Maryam Rasoolzadeh, Marzieh Nazari
Abstract: Development of ultrafine grained and nanostructured materials helps other disciplines and has made a meaningful contribution to other fields especially materials and building construction. New nanostructured materials open new horizons to scientific bases of building and construction materials. Sustecture - sustainable high-tech architecture is to meet new life architectural prerequisites regarding latest achievements in material engineering and new materials developments especially smart and nanostructured materials. Despite this fact, usage of new composite materials in building construction industry had yet to be widespread. Therefore the most important question which is remained to be answered is: what are the most challenges regarding to usage of nanostructured materials in contemporary building construction? Logical argumentation has been adopted as research method of this paper to answer research question, which finalized by descriptive - analytical techniques and depth diagnostic interviews. Samples have been selected randomly among from three major groups namely: 1-accademic scholars, 2-architectural consultants and 3-construction practitioners. The research is to find out the level of their awareness about new developed nanomaterials. In order to find out what are the most challenging issues which prohibited sustecture in achievement of its goals and objectives? The results of the paper show that level of technical knowledge and public awareness regarding to developments of new materials is not in a satisfactory condition especially in building construction and architectural performance side. In other word, however general knowledge regarding to ultrafine grained and nanostructured materials enhanced among architectural contributors, there is not enough technical knowledge among construction practitioners.
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