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Explosive Surface Hardening of Austenitic Stainless Steel

IOP Conference Series: materials science and engineering 2016年第1期123卷

作者： T Kovacs-Coskun Obuda University Banki Donat Faculty of Mechanical and Safety Engineering - Material Science Department - 1081 Budapest - Hungary

In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea mean indirect hardening setup. Austenitic stainless steels have high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

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Thermodynamically consistent phase field theory of phase transformations with anisotropic interface energies and stresses

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Physical Review B 2015年第14期92卷 144106-144106页

作者： Valery I. Levitas James A. Warren Iowa State University Departments of Aerospace Engineering Mechanical Engineering and Material Science and Engineering Ames Iowa 50011 USA Material Measurement Laboratory National Institute of Standards and Technology Gaithersburg Maryland 20899 USA

The main focus of this paper is to introduce, in a thermodynamically consistent manner, an anisotropic interface energy into a phase field theory for phase transformations. Here we use a small strain formulation for simplicity, but we retain some geometric nonlinearities, which are necessary for introducing correct interface stresses. Previous theories have assumed the free energy density (i.e., gradient energy) is an anisotropic function of the gradient of the order parameters in the current (deformed) state, which yields a nonsymmetric Cauchy stress tensor. This violates two fundamental principles: the angular momentum equation and the principle of material objectivity. Here, it is justified that for a noncontradictory theory the gradient energy must be an isotropic function of the gradient of the order parameters in the current state, which also depends anisotropically on the direction of the gradient of the order parameters in the reference state. A complete system of thermodynamically consistent equations is presented. We find that the main contribution to the Ginzburg-Landau equation resulting from small strains arises from the anisotropy of the interface energy, which was neglected before. The explicit expression for the free energy is justified. An analytical solution for the nonequilibrium interface and critical nucleus has been found and a parametric study is performed for orientation dependence of the interface energy and width as well as the distribution of interface stresses.

关键词： FREE energy (Thermodynamics) PHASE transformations (Physics) NONLINEAR theories ENERGY density CAUCHY problem

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Vertically aligned nanocomposite oxide thin films with enhanced ionic conductivity 228

Vertically aligned nanocomposite oxide thin films with enhan...

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Symposium on Ionic Conducting Oxide Thin Films - 228th ECS Meeting

作者： Su, Qing Zhang, Wenrui Jacob, Clement Yoon, Daeil Manthiram, Arumugam Wang, Haiyan Department of Material Science and Engineering Texas A and M University College StationTX77843-3128 United States Department of Electrical and Computer Engineering Texas A and M University College StationTX77843-3128 United States Electrochemical Energy Laboratory Materials Science and Engineering Program University of Texas at Austin AustinTX78712 United States

ISBN: (纸本)9781607685395

Oxide thin films with high ionic conductivity are crucial for sustainable energy production systems such as fuel cells that provide efficient and environmental-friendly energy. Key materials science efforts are associated with developing such oxides with high ionic conductivity. Of particular importance for developing thin film oxide materials is high performance and good stability in the operation temperature range. In this paper, vertically aligned nanocomposites (VAN) approach is reviewed. It creates vertical interfaces of two oxide materials and provides a new design paradigm to manipulate functionalities that cannot be obtained in individual constituents. Two major examples corresponding to ionic conducting oxide thin films in the VAN form presented are: (1) vertically aligned electrolyte/electrolyte nanocomposites with superior vertical ionic conductivity, and (2) vertically aligned electrode/electrolyte nanocomposites as an interlayer to increase the catalytic reaction probability. Finally, opportunities of tuning functionalities of such VAN systems are introduced. © The Electrochemical Society.

关键词： Nanocomposites

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Distributed manufacturing with 3-D printing: a case study of recreational vehicle solar photovoltaic mounting systems

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Journal of Frugal Innovation 2015年第1期1卷 1-7页

作者： Ben Wittbrodt John Laureto Brennan Tymrak Joshua M Pearce Material Science and Engineering Michigan Technological University Houghton USA Mechanical Engineering and Engineering Mechanics Michigan Technological University Houghton USA Electrical & Computer Engineering Michigan Technological University Houghton USA

For the first time, low-cost open-source 3-D printing provides the potential for distributed manufacturing at the household scale of customized, high-value, and complex products. To explore the potential of this type of ultra-distributed manufacturing, which has been shown to reduce environmental impact compared to conventional manufacturing, this paper presents a case study of a 3-D printable parametric design for recreational vehicle (RV) solar photovoltaic (PV) racking systems. The design is a four-corner mounting device with the ability to customize the tilt angle and height of the standoff. This enables performance optimization of the PV system for a given latitude, which is variable as RVs are geographically mobile. The open-source 3-D printable designs are fabricated and analyzed for print time, print electricity consumption, mechanical properties, and economic costs. The preliminary results show distributed manufacturing of the case study product results in an order of magnitude reduction in economic cost for equivalent products. In addition, these cost savings are maintained while improving the functionality of the racking system. The additional electrical output for a case study RV PV system with improved tilt angle functionality in three representative locations in the U.S. was found to be on average over 20% higher than that for conventional mass-manufactured racking systems. The preliminary results make it clear that distributed manufacturing - even at the household level - with open-source 3-D printers is technically viable and economically beneficial. Further research is needed to expand the results of this preliminary study to other types of products.

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Temperature Dependence of Raman Scattering in 4H-SiC Films under Different Growth Conditions

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Chinese Physics Letters 2015年第4期32卷 134-138页

作者：王洪朝何依婷孙华阳丘志仁谢灯梅霆 Tin C. C 冯哲川 Institute of Optoelectronic Material and Technology South China Normal University Guangzhou 510631 State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering Sun YatSen University Guangzhou 510275 The Key Laboratory of Space Applied Physics and Chemistry Ministry of Education and Shaanxi Key Laboratory ofOptical Information Technology School of Science Northwestern Polytechnical University Xi'an 710072 Department of Mechanical Engineering University of Malaya Kuala Lumpur 50603 Malaysia College of Physics Science and Technology and GXU-NAOC Center for Astrophysics and Space Science Guangxi University Nanning 530004

The microRaman scattering of 4H-SiC films, fabricated by low pressure chemical vapor deposition under different growth conditions, is investigated at temperatures ranging from 80 K to 550K. The effects of growth conditions on E2 （TO）, E1 （TO） and A1 （LO） phonon mode frequencies are negligible. The temperature dependences of phonon linewidth and lifetime of E2 （TO） modes are analyzed in terms of an anharmonic damping effect induced by thermal and growth conditions. The results show that the lifetime of E2 （TO） mode increases when the quality of the sample improves. Unlike other phone modes, Raman shift of A1 （longitudinal optical plasma coupling （LOPC）） mode does not decrease monotonously when the temperature increases, but tends to blueshift at low temperatures and to redshift at relatively high temperatures. Theoretical analyses are given for the abnormal phenomena of A1 （LOPC） mode in 4H-SiC.

关键词： Ra SiC Temperature Dependence of Raman Scattering in 4H-SiC Films under Different Growth Conditions

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Rotor load analysis method for twin Screw compressors with considering gaseous pressure and working temperature 14

Rotor load analysis method for twin Screw compressors with c...

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14th International Federation for the Promotion of Mechanism and Machine science World Congress, IFToMM 2015

作者： Hsu, Ruei-Hung Wu, Yu-Ren Wu, Wei-Te Tran, Van-The Bachelor's Program in Precision System Design Feng Chia University Taichung Taiwan Department of Mechanical Engineering National Central University Taoyuan Taiwan Department of Biomechatronics Engineering National Pingtung University of Science and Technology Pingtung Taiwan

ISBN: (纸本)9789860460988

Screw rotors of a twin screw compressor often deform and interfere due to the cyclic gas pressure and working temperature, which lead to noise, vibration and abrasion of the screw rotors. Therefore, this paper proposed a simplified CAE (Computer Aided engineering) method instead of the past massive and complex CFD (Computational Fluid Dynamics) method to simulate and estimate reasonably the screw rotor load and deformation with considering the gas pressure and working temperature applied on its operating process. The analysis results could provide the possible maximum rotor deformation and cyclic load acting on the rotors for design consideration.

关键词： Deformation

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Investigation of 3D printing parameters of shape memory alloy powders

Investigation of 3D printing parameters of shape memory allo...

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materials science and Technology Conference and Exhibition 2015, MS and T 2015

作者： Caputo, Matthew Krizner, Mike Virgil Solomon, C. Materials Science and Engineering Program Youngstown State University One University Plaza YoungstownOH44555 United States Mechanical and Industrial Engineering Youngstown State University One University Plaza YoungstownOH44555 United States

ISBN: (纸本)9781510813939

Additive manufacturing (AM) is an emerging technology for creating near-net shape solid parts. Three dimensional printing (3DP) resembles ink jet printing, but with multiple passes to build materials upward using binder deposition layer by layer into a 3D part. The goal of this work is to determine the manufacturing parameters for 3DP of Ni-Mn-Ga shape memory alloy powders. The cause for an initial failed attempt to print as-spark powders was related to the irregular shape and size of starting materials. Using mechanical separation methods, the powder was separated into two categories: irregular shaped and spherical particles. The spherical powders were further sieved in several class sizes. Within each class the size distribution was determined by image analysis of scanning electron micrographs. This paper will report on the separation methodology to increase spherical particles gain, and printing parameters considered for improving mechanical integrity of 3D printed parts. © Copyright 2015 MS&T15.

关键词： 3D printers

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Pseudogap phase of cuprate superconductors confined by Fermi surface topology

arXiv

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arXiv 2017年

作者： Doiron-Leyraud, N. Cyr-Choinière, O. Badoux, S. Ataei, A. Collignon, C. Gourgout, A. Dufour-Beauséjour, S. Tafti, F.F. Laliberté, F. Boulanger, M.-E. Matusiak, M. Graf, D. Kim, M. Zhou, J.-S. Momono, N. Kurosawa, T. Takagi, H. Taillefer, Louis Institut Quantique Département de Physique & RQMP Université de Sherbrooke SherbrookeQCJ1K 2R1 Canada Institute of Low Temperature and Structure Research Polish Academy of Sciences Wroclaw50-422 Poland National High Magnetic Field Laboratory Florida State University TallahasseeFL32306 United States École Polytechnique CNRS Université Paris-Saclay Palaiseau91128 France Collège de France Paris75005 France Materials Science and Engineering Program/Mechanical Engineering University of Texas - Austin AustinTX78712 United States Department of Applied Sciences Muroran Institute of Technology Muroran050-8585 Japan Department of Physics Hokkaido University Sapporo060-0810 Japan Department of Advanced Materials University of Tokyo Kashiwa277-8561 Japan Canadian Institute for Advanced Research TorontoONM5G 1Z8 Canada

The properties of cuprate high-temperature superconductors are largely shaped by competing phases whose nature is often a mystery. Chiefly among them is the pseudogap phase, which sets in at a doping p* that is material-dependent. What determines p* is currently an open question. Here we show that the pseudogap cannot open on an electron-like Fermi surface, and can only exist below the doping pFS at which the large Fermi surface goes from hole-like to electron-like, so that p* ≤ pFS. We derive this result from high-magnetic-field transport measurements in La1.6−xNd0.4SrxCuO4 under pressure, which reveal a large and unexpected shift of p* with pressure, driven by a corresponding shift in pFS. This necessary condition for pseudogap formation, imposed by details of the Fermi surface, is a strong constraint for theories of the pseudogap phase. Our finding that p* can be tuned with a modest pressure opens a new route for experimental studies of the pseudogap. Copyright © 2017, The Authors. All rights reserved.

关键词： Fermi surface

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Analysis of thin-walled shells with inner ribs formed by inner spinning technology

Analysis of thin-walled shells with inner ribs formed by inn...

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作者： Wang, Z. Ma, S. Education Ministry Key Laboratory of Advanced Forging and Stamping Science and Technology College of Mechanical Engineering Yanshan University Qinhuangdao Hebei066004 China Special Material and Technic Institution of Aerospace Beijing100074 China

This study analysed the formation of thin-walled shells with inner reinforcing ribs formed by conventional spinning technology through the design of three different blanks. Various factors and processing parameters, which affected the formation of the product, were studied. It was discovered that the spinning times were influenced by the expansion ratios and the inner ring reinforcing ribs. The impacts of spindle speed and spinning roller radius on the formation of the thin-walled shells with inner ribs were found to be identical. The specimens formed by the inner spinning technology exhibited two kinds of failure modes, which are described and explained. © W. S. Maney & Son Ltd 2015.

关键词： Shells (structures)

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Study on preparation and flame retardant properties of epoxy/graphene oxide nanosheets composites 20

Study on preparation and flame retardant properties of epoxy...

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20th International Conference on Composite materials, ICCM 2015

作者： Chen, Wei-Jen Shen, Ming-Yuan Yang, Jia-Ming Chiang, Chin-Lung Department of Aviation Mechanical Engineering China University of Science and Technology 530 Sec. 3 Zhongshan Rd. Hukou Township Hsinchu County303 Taiwan Department of Aviation Mechanical Engineering China University of Science and Technology 530 Sec. 3 Zhongshan Rd Hukou Township Hsinchu County303 Taiwan Green Flame Retardant Material Research Laboratory Department of Safety Health and Environmental Engineering Hung-Kuang University Taichung433 Taiwan Green Flame Retardant Material Research Laboratory Department of Safety Health and Environmental Engineering Hung-Kuang University Taichung433 Taiwan

Epoxy is extensively used in everyday life, in coatings, semiconductor packaging, electrical equipment, insulation and adhesives. Since epoxy has very favorable mechanical properties and low shrinkage characteristics when cured, it has attracted much interest. However, since it is flammable, its development has been limited by its flammability. The flame retardant containing silicon and phosphorus was grafted onto the surface of graphene oxide nanosheets (GON) via a condensation reaction. Fourier transform infrared spectroscopy verifies that flame retardant did not only covalently bond to GON as a functionalization moiety, but partly restored its conjugated structure as a reducing agent. The flame retardant on graphene sheets oxide was observed by transmission electron microscopy. The flame retardancy and thermal stability of epoxy/functionalized GON (f-GON) nanocomposites that contain various weight fractions of f-GON were studied using the limiting oxygen index test, UL-94 test and by thermogravimetric analysis in nitrogen. The composites containing 10 wt% f-GON can pass V-0 rating in UL-94 test. Adding 10 wt % f-GON in epoxy greatly increased the char yield and LOI by 42% and 80%, respectively. Epoxy/f-GON nanocomposites with phosphorus, silicon and graphene layer structures were found to exhibit much greater flame retardancy than neat epoxy. The synergistic effects among silicon, phosphorus and GON can improve the flame retardancy of epoxy resin. The phosphorus, silicon and GON layer structures of DPPES-GNO caused the continuous and insulating char layer to protect the inner polymer matrix. The approach that is described herein has great potential for the development of a novel synergistic phosphorus/silicon-graphene nanosheets oxide flame-retardant with polymer nanocomposite applications. © 2015 International Committee on Composite materials. All rights reserved.

关键词： Epoxy Flame retardant Graphene oxide nanosheets Phosphorus Silicon

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