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971.
Jun-Young Cho Tae-Ho An Soo Young Shin Hwang Sun Kim Young Seok Kim Hyunick Shin Sung-Hwan Bae Miyoung Kim Seong-Hyeon Hong Chan Park 《Bulletin of Materials Science》2018,41(6):157
The effects of sintering conditions on the microstructure and mechanical properties of the sintered SiC prepared using the SiC powder recovered from the kerf loss sludge were investigated. The recovered SiC powders were consolidated by spark plasma sintering (SPS) and conventional sintering methods. The effects of sintering temperature, time and methods (SPS and conventional sintering) on the phase, grain size and density of SiC were systematically studied. The Vickers hardness of spark plasma-sintered (SPSed) samples was higher than that of conventional sintered samples due to small grain size. When holding time was increased from 10 to 30 min, the grain size and relative density of SPSed samples were also increased, which lead to the almost constant Vickers hardness by competing effects of grain size and relative density. When holding time was over 30 min, no appreciable change of the relative density and grain size were observed, which can lead to similar values of Vickers hardness. SPS process can be used to make SiC with high density and hardness at relatively low temperature compared with the conventional sintering process. 相似文献
972.
973.
Aya Shin Marc Chevalier Eleanor Laney Jonathan Pearson 《Materials at High Temperatures》2018,35(1-3):30-38
AbstractEDF Energy operates 14 advanced gas cooled reactors (AGRs) in the UK to generate electricity. CO2 gas is used as the primary coolant in the AGRs, and a range of steels are used as for the structural components: e.g. 9Cr-1Mo ferritic steels and stainless steels. These steels are susceptible to both oxidation and carburisation in CO2 dominated primary coolant gas under high pressure between 300 and 650 °C. Material degradation is a key concern for lifetime extension of the power stations, and EDF Energy and its predecessors have carried out a series of research programmes to better understand steel oxidation behaviour in AGRs and to develop more realistic lifetime prediction methodologies. These are used to secure safe and reliable operation of the AGRs. In this paper, an overview of oxidation behaviour of steels used in AGRs and some examples from the above programmes are described. 相似文献
974.
On the treatments of heterogeneities and periodic boundary conditions for isogeometric homogenization analysis
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Seishiro Matsubara Shin‐Nosuke Nishi Kenjiro Terada 《International journal for numerical methods in engineering》2017,109(11):1523-1548
The treatments of heterogeneities and periodic boundary conditions are explored to properly perform isogeometric analysis (IGA) based on NURBS basis functions in solving homogenization problems for heterogeneous media with omni‐directional periodicity and composite plates with in‐plane periodicity. Because the treatment of the combination of different materials in IGA models is not trivial especially for periodicity constraints, the first priority is to clearly specify points at issue in the numerical modeling, or equivalently mesh generation, for IG homogenization analysis (IGHA). The most awkward, but important issue is how to generate patches for NURBS representation of the geometry of a rectangular parallelepiped unit cell to realize appropriate deformations in consideration of the convex‐hull property of IGA. The issue arises from the introduction of overlapped control points located at angular points in the heterogeneous unit cell, which must satisfy multiple point constraint (MPC) conditions associated with periodic boundary conditions (PBCs). Although two measures may be conceivable, we suggest the use of multiple patches along with double MPC that imposes PBCs and the continuity conditions between different patches simultaneously. Several numerical examples of numerical material and plate tests are presented to demonstrate the validity of the proposed strategy of IG modeling for IGHA. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
975.
Seung-Min Lee Wonchul Choi Junsoo Kim Taekwang Kim Jaewoo Lee Sol Yee Im Jung Yoon Kwon Sunae Seo Mincheol Shin Seung Eon Moon 《International Journal of Thermophysics》2017,38(12):176
On Si and sapphire substrates, 6–45 nm thick films of atomic layer-deposited Al\(_{2}\)O\(_{3}\) were grown. The thermal conductivity of ALD films has been determined from a linear relation between film thickness and thermal resistance measured by the 3\(\omega \) method. ALD films on Si and sapphire showed almost same thermal conductivity in the temperature range of 50–350 K. Residual thermal resistance was also obtained by extrapolation of the linear fit and was modeled as a sum of the thermal boundary resistances at heater–film and film–substrate interfaces. The total thermal resistance addenda for films on sapphire was close to independently measured thermal boundary resistance of heater–sapphire interface. From the result, it was deduced that the thermal boundary resistance at ALD Al\(_{2}\)O\(_{3}\)–sapphire interface was much lower than that of heater–film. By contrast, the films on Si showed significantly larger thermal boundary resistance than films on sapphire. Data of \(< 30\) nm films on Si were excluded because an AC coupling of electrical heating voltage to semiconductive Si complicated the relation between 3\(\omega \) voltage and temperature. 相似文献
976.
Flexible Hard Coating: Glass‐Like Wear Resistant,Yet Plastic‐Like Compliant,Transparent Protective Coating for Foldable Displays
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Gwang‐Mun Choi Jungho Jin Dahye Shin Yun Hyeok Kim Ji‐Hoon Ko Hyeon‐Gyun Im Junho Jang Dongchan Jang Byeong‐Soo Bae 《Advanced materials (Deerfield Beach, Fla.)》2017,29(19)
A flexible hard coating for foldable displays is realized by the highly cross‐linked siloxane hybrid using structure–property relationships in organic–inorganic hybridization. Glass‐like wear resistance, plastic‐like flexibility, and highly elastic resilience are demonstrated together with outstanding optical transparency. It provides a framework for the application of siloxane hybrids in protective hard coatings with high scratch resistance and flexibility for foldable displays. 相似文献
977.
Interface Control of Ferroelectricity in an SrRuO3/BaTiO3/SrRuO3 Capacitor and its Critical Thickness
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Yeong Jae Shin Yoonkoo Kim Sung‐Jin Kang Ho‐Hyun Nahm Pattukkannu Murugavel Jeong Rae Kim Myung Rae Cho Lingfei Wang Sang Mo Yang Jong‐Gul Yoon Jin‐Seok Chung Miyoung Kim Hua Zhou Seo Hyoung Chang Tae Won Noh 《Advanced materials (Deerfield Beach, Fla.)》2017,29(19)
The atomic‐scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure during growth plays an important role in controlling the interfacial terminations of SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high (around 150 mTorr), usually exhibits a mixture of RuO2–BaO and SrO–TiO2 terminations. By reducing , the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO–TiO2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells. 相似文献
978.
Fabrication of Millimeter‐Long Carbon Tubular Nanostructures Using the Self‐Rolling Process Inherent in Elastic Protein Layers
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Hyojin Ko Leila F. Deravi Sung‐Jin Park Jingon Jang Takhee Lee Cheong Kang Jin Seok Lee Kevin Kit Parker Kwanwoo Shin 《Advanced materials (Deerfield Beach, Fla.)》2017,29(31)
Millimeter‐long conducting fibers can be fabricated from carbon nanomaterials via a simple method involving the release of a prestrained protein layer. This study shows how a self‐rolling process initiated by polymerization of a micropatterned layer of fibronectin (FN) results in the production of carbon nanomaterial‐based microtubular fibers. The process begins with deposition of carbon nanotube (CNT) or graphene oxide (GO) particles on the FN layer. Before polymerization, particles are discrete and nonconducting, but after polymerization the carbon materials become entangled to form an interconnected conducting network clad by FN. Selective removal of FN using high‐temperature combustion yields freestanding CNT or reduced GO microtubular fibers. The properties of these fibers are characterized using atomic force microscopy and Raman spectroscopy. The data suggest that this method may provide a ready route to rapid design and fabrication of aligned biohybrid nanomaterials potentially useful for future electronic applications. 相似文献
979.
Hiroya Nishikawa Kazuya Shiroshita Hiroki Higuchi Yasushi Okumura Yasuhiro Haseba Shin‐ichi Yamamoto Koki Sago Hirotsugu Kikuchi 《Advanced materials (Deerfield Beach, Fla.)》2017,29(43)
An anomalously large dielectric permittivity of ≈104 is found in the mesophase temperature range (MP phase) wherein high fluidity is observed for a liquid‐crystal compound having a 1,3‐dioxane unit in the mesogenic core (DIO). In this temperature range, no sharp X‐ray diffraction peak is observed at both small and wide Bragg angles, similar to that for a nematic phase; however, an inhomogeneous sandy texture or broken Schlieren one is observed via polarizing optical microscopy, unlike that for a conventional nematic phase. DIO exhibits polarization switching with a large polarization value, i.e., P = 4.4 µC cm?2, and a parallelogram‐shaped polarization–electric field hysteresis loop in the MP phase. The inhomogeneously aligned DIO in the absence of an electric field adopts a uniform orientation along an applied electric field when field‐induced polarization switching occurs. Furthermore, sufficiently larger second‐harmonic generation is observed for DIO in the MP phase. Second‐harmonic‐generation interferometry clearly shows that the sense of polarization is inverted when the +/? sign of the applied electric field in MP is reversed. These results suggest that a unidirectional, ferroelectric‐like parallel polar arrangement of the molecules is generated along the director in the MP phase. 相似文献
980.
Wanjun Liu Yu Shrike Zhang Marcel A. Heinrich Fabio De Ferrari Hae Lin Jang Syeda Mahwish Bakht Mario Moisés Alvarez Jingzhou Yang Yi‐Chen Li Grissel Trujillo‐de Santiago Amir K. Miri Kai Zhu Parastoo Khoshakhlagh Gyan Prakash Hao Cheng Xiaofei Guan Zhe Zhong Jie Ju Geyunjian Harry Zhu Xiangyu Jin Su Ryon Shin Mehmet Remzi Dokmeci Ali Khademhosseini 《Advanced materials (Deerfield Beach, Fla.)》2017,29(3)