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Impurity Segregation at TGO/Bondcoat Interfaces and Its Effect on TGO Adherence

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中国腐蚀与防护学报 2009年第4期29卷 277-285页

作者： p. y. HOU Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley CA 94720 USA

Impurity segregation at the interfaces between thermally grown aluminum oxide and a few coatings deposited on single crystal Ni-based superalloys are *** are compared with studies made at oxide/metal interfaces formed on model Al_2O_3-forming *** coatings were NiptAl on CMSX4 or AM1 with two different bulk sulfur contents,and NiCoCrAly on *** electron microscopy was used to study the chemistry at the TGO/coating interface after portions of the oxide scale were removed in ultra high vacuum by scratching the oxidized *** extent of oxide spallation in relation to the scratch width was utilized to evaluate the interfacial strength,which was then related to the interface chemistry,particular its sulfur *** show strong relationship between sulfur segregation and the alloy substrate *** relationship is discussed in terms of the effects of pt,Hf,y and Cr and the alloy sulfur content.

关键词： TGO 金属腐蚀防护

Fabrication of large-bulk ultrafine grained 6061 aluminum alloy by rolling and low-heat-input friction stir welding

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Journal of Materials Science & Technology 2018年第1期34卷 112-118页

作者： C.y.Liu B.Qu p.Xue Z.y.Ma K.Luo M.Z.Ma R.p.Liu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Key Laboratory of New processing Technology for Nonferrous Metal & Materials Ministry of Education Guilin University of Technology Guangxi Key Laboratory of Universities for Clean Metallurgy and Comprehensive Utilization of Nonferrous Metal Resources Guilin University of Technology State Key Laboratory of Metastable Materials Science and Technology Yanshan University

In this study, the ultrafine grained （UFG） 6061 Al alloys fabricated by cold rolling were friction stir welded （FSW） with different rotation rates under both air cooling and rapid cooling in water. Low-heat-input parameters of 400 rpm rotation rate in water （400-Water） could effectively inhibit the coarsening of recrystallized grains, reduce the precipitation rate, and retain more dislocations of the UFG 6061 Al parent metal. 400-Water joint showed high lowest-hardness value, narrow low-hardness zone, and high tensile strength, attributing to the effect of dislocation, grain boundary, solid-solution, and precipitation hardening. This work provides an effective strategy to fabricate large-sized bulk UFG AI alloy by cold rolling with large deformation and low-heat-input FSW.

关键词： Aluminum alloys Ultrafine grained materia Friction stir welding Mechanical properties

Twinning behavior of hot extruded AZ31 hexagonal prisms during uniaxial compression

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Journal of Magnesium and Alloys 2019年第1期7卷 90-97页

作者： y.R.Zhao L.L.Chang J.Guo y.p.Jin School of Materials Science and Engineering Shandong UniversityJinanShandong 250061China Key Laboratory for Liquid-Solid Structure Evolution and processing of Materials Ministry of EducationShandong UniversityJinan 250061China

Hot-extruded magnesium alloy AZ31 bar was cut into hexagonal prisms and then compressed at room temperature with the loading direction parallel to the extrusion direction(ED)or perpendicular to *** effective stress and strain evolution at center and corner region of the hexagonal prisms was simulated by using DEFORM 3D,while microstructure evolution was characterized by electron backscatter diffraction(EBSD).Relationship between twinning behavior and stress-strain evolution during compression at room temperature was *** results indicated that the compressive stress and strain levels at central region of hexagonal prisms were lower than those at the corner *** examination revealed that{10-12}twins activate during the compression and the volume fraction of twins at corner parts were less than that at the central parts,which was attributed to twin thickening and coalescence ***,the EBSD map indicated that the arise of{10-11}contraction twins and{10-11}-{10-12}double twins in compressed samples,especially in the corner region with loading axis perpendicular to ED,which were considered to be related to the high stress level at corner *** dislocation slips led to low-angle boundaries in LA⊥ED and LA//ED.

关键词： Magnesium alloy Simulation Microstructure Twinning Coalescence

Comparing the Effectiveness of Motor Control Exercises versus Mckenzie Exercises for Work Related Back pain

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Open Journal of Therapy and Rehabilitation 2016年第3期4卷 178-185页

作者： Tanvi Tanna Senthilkumar Thiyagarajan prabhu chinna Gounder Department of Musculoskeletal and Sports The Oxford College of Physiotherapy Bangalore India

Background: Work related low back pain has been identified as a one of the most costly disorders among the worldwide working population. This condition was highly prevalent that approximately 85% patients having back pain were brought on by prolonged sitting. With the rapid development of modern technology, sitting has now become the most common posture in today’s work- place. Idea of using motor control learning approach provides the optimal control and coordination of the spine. The McKenzie evaluation was received using repeated movements and sustained positions. Therefore high quality randomized clinical trial was required to compare the effectiveness of these treatments for work related low back pain. Objectives: To compare the effectiveness of motor control exercises and McKenzie exercises in reducing pain and disability in work related low back pain. Method: The study included 40 subjects with work related low back pain due to prolonged sitting. They were randomly allocated into two groups (Group A and Group B). Group A was treated with motor control exercises and group B was treated with McKenzie exercises for 4 weeks. Results: Both the groups have shown statically significant improvement in vas with p p parison was done after the 4 weeks, the percentage of improvement in group A was much higher than Group B. Conclusion: The study concluded that motor control exercises have shown statically and clinically significant improvement in reducing pain and disability when compared to McKenzie exercises among work related low back pain subjects.

关键词： Low Back pain (LBp) Oswestry Disability Index (ODI) Motor Control Exercise (MCE) McKenzie Exercise (MKZ) Visual Analogue Scale (VAS)

Electron Spin Resonance Studies of Mn^2＋ in Freshwater Snail Shells： pomacea Canaliculata Lamarck and Fossilized Snail Shell

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Chinese physics Letters 2005年第7期22卷 1780-1783页

作者： N.Udomkan S.Meejoo p.Limsuwan p.Winotai y.Chaimanee DepartmentofChemistry FacultyofScienceMahidolUniversityRamaVIRoadBangkok10400_Thailand Departmentofphysics FacultyofScienceKingMongkut'sUniversityofTechnologyThonburiPrachautidRoadBangkok10140Thailand paleontologySection GeologicalSurveyDivisionDepartmentofMineralResourcesRamaVIRoadBangkok10400Thailand Departmentofphysics FacultyofScienceKingMongkut'sUniversityofTechnologyThonburiPrachautidRoadBangkok10140Thailand//846/227BangmodPrachautid44ThungkruBangkok10140Thailand

We study paramagnetic Mn2+ ions present in the nowadays shells of univalve freshwater snails of pomacea canaliculata lamarck (pCL) and the fossilized freshwater snail (FFS), Viviparus. All these shells are abundant in Thailand. The pCL shells were ground into fine powder. A set of seven samples were then separately annealed for 2h in air atmosphere at different annealing temperatures while the FFS powder was characterized as-received. The pCL shells mainly consist of aragonite and a fraction of calcite. The heat treatments of the pCL powder samples at temperature higher than 450 degrees C resulted in an irreversible phase transformation from aragonite to calcite. However, it is found that the FFS shell is mainly made of calcite, with a minor fraction of aragonite. The crystal structure of the high-temperature-annealed pCL samples are quite similar to that of FFS, which indicates that the metamorphosis (aragonite → calcite) in the FFS shell had occurred but was not yet completed, although it had remained under the pressure and temperature of the Earth's crusts over millions of years. Our detailed ESR spectral analyses of pCL and FFS show that Mn2+ ions enter the Ca2+ sites during a biomineralization process. Simulated ESR parameters of pCL-500 of Mn2+ at a uniaxial site of calcite are reported. It is surprising to find that the ratio of Mn2+ concentration present in FFS to those in pCL shells evaluated from ESR spectra is as much as 10:1.

关键词： EGAT pCL ESR

Simulation of kinematic and workspace analysis of 3-pRS parallel manipulator

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International Journal of Modeling, Simulation, and Scientific Computing 2015年第1期6卷 111-122页

作者： y.D.patel p.M.George Department of Mechanical Engineering A.D.patel Institute of Technology New Vallabh Vidyanagar GujaratIndia Department of Mechanical Engineering Birla Vishvakarma Mahavidyalaya Engineering College Vallabh Vidyanagar India

In the present era,the competitive producers are forced to use maximally newer advanced technology and its effective fast implementation using various available tools for synthesis of new product *** of current state of art computer aided technology supports the creation of flexible assemblies and their built up though unified modular *** design of robotic mechanism is a complex process involving geometric,kinematic,singularity analyses during its synthesis *** present work is aimed at the effective utilization of CAx system pro/Engineer tools for creation,ease in modifi-cation and analysis of spatial parallel *** degrees of freedom of 3-pRS parallel manipulator is obtained using mobility *** manipulator with 3-DOF with 3-pRS configuration is *** kinematics simulation of the robot is carried out using mechanism simulation and compared with closed form *** concept of reachable,orientation and dexterous workspace is *** tip coordinates obtained through simulation are plotted for workspace *** and outer workspace boundaries are developed and analyzed for four different cases to understand the problem of interior singularity within workspace.

关键词： parallel manipulator mobility constraints workspace

Molecular cloning of rice cDNAs related to pollen development using the subtraction hybridization technique

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Chinese Science Bulletin 1999年第20期44卷 1898-1903页

作者： Zee S.y yau C.p. The Botany Department University of Hong Kong Hong Kong ChinaThe Botany Department University of Hong Kong Hong Kong China

The meiotic stage of pollen mother cell is a very important stage in controlling the development and formation of pollen. In order to clone the rice cDNA(s) of this stage, a normal rice, Annong N and its thermosensitive mutant, Annong S-1 were used as the plant material. The mRNA has been extracted from the young panicle at the meiotic stage. By using the cDNA subtraction hybridization technique, three cDNA fragments, Rp-1, Rp-2 and Rp-3 have

关键词： cDNA subtraction hybridization pollen development rice.

Bio-amelioration of alkali soils through agroforestry systems in central Indo-Gangetic plains of India

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Journal of Forestry Research 2014年第4期25卷 887-896页

作者： y.p.Singh Gurbachan Singh D.K.Sharma Central Soil Salinity Research Institute Regional Research StationLucknow (U.P.) 226005 India Indian Council of Agricultural Research New Delhi 110001 India Central Soil Salinity Research Institute Karnal Haryana 132001 India

A long-term field study was initiated during 1995 at Central Soil Salinity Research Institute, Regional Research Station, Lucknow （26047＇58＂ N and 80°46＇24＂ E） to analyze the effect of agroforestry systems on amelioration of alkali soils. Three agroforestry systems （pas- toral, silvipastoral and silvicultural） were compared with the control where no agroforestry system was introduced. Tree-based silvicultural and silvipastoral systems were characterized by tree species prosopis juliflora and Acacia nilotica along with grass species Leptochloafusca, panicum maximum, Trifolium alexandrium and Chloris gayana. Growth of ten-year-old prosopis juliflora and Acacia nilotica planted in combi- nation with grasses was significantly higher over the silviculture system with the same species. Tree biomass yields of p. juliflora （77.20 t·ha-1） and A. nilotica （63.20 t·ha-1） planted under silvipastoral system were significantly higher than the sole plantation of （64.50 t·ha-1 and 52.75 t·ha-1）. Fodder yield under the pastoral system was significantly higher than the silvipastoral system during initial years but it was at par with that of silvipastoral systems after eight years of plantation. The microbial biomass carbon in the soils of silvipastoral systems was significantly higher than in soils under sole plantation of trees and control systems. The prosopis-based silvipastoral system proved more effective in reduc- ing soil pH, displacing Na＋ from the exchange complex, increasing or- ganic carbon and available N, p and K. Improvement in soil physical properties such as bulk density, porosity, soil moisture and infiltration rate was higher in the prosopis-based silvipastoral system than in the silviculture system or control On the basis of biomass production and improvement in soil health due to tree ＋ grass systems, silvipastoral agroforestry system could be adopted for sustainable reclamation ofhighly alkali soils.

关键词： agroforcstry systems alkali soils biomass production mi-crobial biomass soil amelioration

pREDICTION FOR FORMING LIMIT OF AL2024T3 SHEET BASED ON DAMAGE THEORy USING FINITE ELEMENT METHOD

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Acta Mechanica Solida Sinica 2006年第2期19卷 174-180页

作者： Tang C.y. Fan Jianping Tsui C.p. Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China

This paper presents the application of anisotropic damage theory to the study of forming limit diagram of A12024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite element cell model has been constructed. The cell model consists of two phases, the aluminum alloy matrix and the intermetallic cluster. The material behavior of the aluminum alloy matrix is described with a fully coupled elasto-plastic damage constitutive equation. The intermetallic cluster is assumed to be elastic and brittle. By varying the stretching ratio, the limiting strains of the sheet under biaxial stretching have been predicted by using the necking criterion proposed. The prediction is in good agreement with the experimental findings. Moreover, the finite element cell model can provide information for understanding the microscopic damage mechanism of the aluminum alloy. Over-estimation of the limit strains may result if the effect of material damage is ignored in the sheet metal forming study.

关键词： forming limit diagram (FLD) anisotropic damage finite element method (FEM) limit strain localized necking elasto-plastic deformation