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IMPROVING THE ACCURACY OF MACHINED PARAMETRIC SURFACES USING CUTTING FORCE SYNTHESIS AND SURFACE OFFSET TECHNIQUES

IMPROVING THE ACCURACY OF MACHINED PARAMETRIC SURFACES USING...

ASME 1997 International mechanical engineering Congress and Exposition, IMECE 1997 - Manufacturing science and engineering

作者： Gadalla, Mohamed A.E. El Maraghy, Waguih H. Dept. of Mechanical and Materials Engineering Faculty of Engineering Science University of Western Ontario LondonONN6A 5B9 Canada Dept. of Industrial and Manufacturing Systems Engineering Faculty of Engineering University of Windsor WindsorONN9B 3P4 Canada

ISBN: (纸本)9780791826782

Prediction of machining errors and compensation for these enors during the tool path generation stage can improve the product quality significantly. A traditional approach would be machining a few parts, followed by a measuring process to estimate the enors, and finally using a scheme to compensate for the enors. In this paper two approaches are used to avoid trial runs. In the first approach prediction of the deflection of the cutting tool (based on modelling of the cutting forces) at certain points distributed on the design surface is calculated. An inverse operator is then applied to these enors to calculate a compensation vector at each point. A variable offset geometrical model was developed that uses these vectors to build the compensated surface. A detailed simulation analysis for the proposed compensation scheme is presented for different surface shapes in both up and down milling. The second approach is based on improving the roughing strategy by leaving a uniform thickness layer during the roughing phase on top of the finished surface. This leads to more uniform distribution of the cutting forces that may improve the accuracy of the finished surface. © 1997 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Cutting tools

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Compositional Effects on the Degradation of PVD-Tisin

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MRS Online Proceedings Library 1997年第1期473卷 241-246页

作者： W. F. McArthur F. Deng K. Ring P. M. Pattison K. L. Kavanagh Electrical and Computer Engineering Dept. Materials Science Program University of California San Diego La Jolla

PVD-TixSiyNz films formed by reactive RF-magnetron co-sputtering of Ti and Si in Ar/N2 are evaluated as a diffusion barrier between Cu and Si. A complete range of compositions are obtained by Ti targets inlaid with Si. Film composition is controlled by the target ratio of titanium to silicon and N2 partial pressure. Electrical results versus thermal history for films of ∼6-18% Si as well as the composition and microstructure as determined by Rutherford back scattering (RBS), TEM and electron diffraction are reported. These films are an amorphous matrix with imbedded nanocrystals of titanium nitride as-deposited and undergo phase separation to yield titanium nitride and silicon nitride after a 1000r.C anneal. As-deposited compositions which lie above the TiN-Si3N4 phase line yield crystals of TiN. Compositions below the TiN-Si3N4 phase line yield crystals of Ti2N. Bulk resistivity as-deposited (<400µΩ-cmµ) is acceptable for use as a contact liner/barrier material and improves with annealing. Si pn-diodes metallized with 20nm Ti40Si15N45 and Cu show no significant increase in reverse leakage current at anneal temperatures below 700r.C.

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Microstructural Defects in SrTiO 3 Bicrystals and Their Influence on YBa 2 Cu 3 O 7 Film Growth and Junction Performance

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MRS Online Proceedings Library 1997年第1期474卷 91-98页

作者： J. W. P. Hsu E. B. McDaniel R. A. Rao C. B. Eom Dept. of Physics Univ. of Virginia Charlottesville USA Dept. of Mechanical Engineering and Materials Science Duke Univ. Durham USA

We use a near-field scanning optical microscope (NSOM) to investigate microstructural defects at the fusion boundaries of SrTiO3 bicrystal substrates. The optical transmission across the fusion boundary shows circular dark spots with diameters varying from 0.1 to 1 fum that are distributed non-uniformly along the boundary. After detailed characterization of the substrates, a thin YBa2Cu3O7 (YBCO) film (∼ 40 nm) was deposited on a 24° bicrystal. Combining NSOM and scanning force microscopy, we show that these substrate defects can cause the grain boundary of a YBCO thin film grown on the bicrystal to wander up to 0.8 micron in the film. Strain fields associated with these substrate defects are attributed to their influence on YBCO growth. The relation between these structural defects and the electrical characteristics of YBCO grain boundary junctions are also discussed.

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COMPARISON OF CAVITATION EROSION TEST RESULTS BETWEEN VIBRATORY AND CAVITATING JET METHODS

COMPARISON OF CAVITATION EROSION TEST RESULTS BETWEEN VIBRAT...

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ASME 1997 International mechanical engineering Congress and Exposition, IMECE 1997

作者： Yamaguchi, Atsushi Kazama, Toshiharu Inoue, Kosuke Onoue, Jiro Dept. of Mechanical Engineering and Materials Science Yokohama National University 79-5 Tokiwadai Hodogaya-ku Yokohama240 Japan Dept. of Mechanical Systems Engineering Muroran Institute of Technology 27-1 Mizumoto-cho Muroran050 Japan Production Engineering Research Laboratory Hitachi Ltd. 292 Yoshida-cho Totsuka-ku Yokohama244 Japan Basic Technology R & D Center Kayaba Ind. Co. Ltd. 1805-1 Asamizodai Sagamihara228 Japan

ISBN: (纸本)9780791818367

The relationship of the test results between the vibratory and cavitating jet methods was clarified experimentally. Six types of metallic specimens which were made of aluminum alloy, superduralumin, high-strength brass, stainless steel, carbon steel and chrome-molybdenum steel were tested. The ratio of eroded volume by the vibratory to cavitating jet methods became constant as the time proceeded. The eroded volume of aluminum alloy was the largest, and that of superduralumin, that of high-strength brass, that of steel, in order. The order agreed well with both test methods. Striation, plastic deformation and fatigue fracture were observed. © 1997 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Aluminum alloys

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Microstructural and Photoluminescence Studies on Europium Doped Yttrium Oxide Films Synthesized by Metallorganic Vapor Deposition

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MRS Online Proceedings Library 1997年第1期495卷 39-43页

作者： G. A. Hirata J. McKittrick J. Yi S. G. Pattillo K. V. Salazar M. Trkula Dept. of Applied Mechanics and Engineering Sciences and Materials Science Program University of California at San Diego La Jolla USA Materials Science and Technology Division Los Alamos National Laboratory Los Alamos USA

The microstructural and luminescence properties of europium doped yttrium oxide (Y2O3:Eu) thin films deposited by metallorganic chemical vapor deposition are presented in this work. It was found that surface morphology, crystallinity and photoluminescent emission properties are strongly dependent on substrate temperature during deposition. The depositions were carried out in a stainless steel chamber using yttrium and europium 2,2,6,6,-tetramethyl-3,5-heptanedionates as volatile precursors and O2 as the reactant gas. Post-annealing increased the crystallite size and decreased the lattice parameter, resulting in an increased photoluminescent emission intensity.

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Experimental Investigation and Thermodynamic Calculation of the Ternary System Mn-Y-Zr

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International Journal of materials Research 1997年第7期88卷 529-538页

作者： Flandorfer, Hans Gröbner, Joachim Stamou, Athanasis Hassiotis, Nikitas Saccone, Adriana Rogl, Peter Wouters, Ria Seifert, Hans Macciò, Daniele Ferro, Riccardo Haidemenopoulos, Gregory Delaey, Luc Effenberg, Günter Universität Wien Institut fur Physikalische Chemie ViennaA-1090 Austria Material Science International Nobelstr. 15 Postfach 800749 StuttgartD-70507 Germany University of Thessaly Laboratory of Materials Dept. of Mechanical Engineering Pedion Areos Volos Greece Universitàdi Genova Dipartimento di Chimica e Chimica Industriale Via Dodecaneso 31 GenovaI-16146 Italy Katholieke Universiteit Leuven Department of Metallurgy and Materials Engineering HeverleeB-3001 Belgium

Phase equilibria were established in the ternary system Mn-Y-Zr for an isothermal section at 800 °C by use of X-ray powder diffraction, light optical microscopy and quantitative EPMA. No ternary compounds were observed. Mutual solid solubilities among the binary phases were found to be generally less than ∼ 2 at.%. Solubility of Mn, Y in αZr at 800 °C was 2.1 at.% Mn and 2.9 at.% Y, whereas no Mn dissolves in α Y. A reinvestigation of the binary solid solubility limits of Mn2Zr1-x at 800 °C by quantitative EPMA and X-ray powder full profile analyses revealed a smaller homogeneous region, Mn2Zr1-x, 0 ≤ x ≤ 0.20, than previously reported in literature. There is little solubility of Y in stoichiometric Mn2Zr and maximum solubility of Mn, Zr in αY was determined from as cast alloys to be 1.8 at.% Mn and 2.4 at.% Zr. Based on this experimental findings and the literature data relevant to the binary systems a thermodynamic calculation of the ternary system was attempted, requesting a significantly higher heat of formation of Mn2Zr than previously reported. A nearly pseudobinary section was experimentally established for the join Y-Mn2Zr with a maximum eutectic at 1072 ± 10°C at 57 at.% Y (calculated at 1064 °C and 58 % Y). Three ternary eutectics were defined: L Mn2Zr + Mn2Y + Mn23Y6 at 1090 ± 10 °C at a composition of Mn75Y23Zr2 (calculated at 1087 °C and at Mn72Y26Zr2), L (αY) + Mn2Y + Mn2Zr at 870 ± 10 °C at a composition of Mn40Y57Zr3 (calculated at 883 °C and at Mn36Y63Zr1) and L (αY)+ (βZr) + Mn2Zr at 1054 ± 10 °C at a composition of Mn26Y15Zr59 (calculated at Mn24Y21Zr55 and at 992 °C). © 1997 Carl Hanser Verlag, München.

关键词： Binary alloys

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Corrosion inhibitors in fertilizer production and handling

Corrosion inhibitors in fertilizer production and handling

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Corrosion 1996

作者： Prabhu-Gaunkar, G.V. Raman, A. Dept. of Metallurgical Engineering and Materials Science Indian Institute of Technology Bombay400076 India Materials Group Dept. of Mechanical Engineering Louisiana State University Baton RougeLA70808 United States

In fertilizer production, storage and handling, corrosion inhibitors play a very important role in ensuring the durability of the equipment and plant structures. The plants handle very corrosive raw materials and several corrosive intermediates and by-products under operating conditions. Fluid velocity and high temperatures and pressures compound the corrosion problems. In this paper an attempt is made to review the materials commonly utilized in the fertilizer plants and the role of inhibitors in mitigating various corrosion problems encountered, based on the chemicals commonly handled and the products generated and distributed. Corrosion inhibitors for liquid ammonium nitrate-urea fertilizer are described in detail. © 1996 by NACE International.

关键词： Ammonia

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Some issues in life assessment of longitudinal seam welds based on creep tests with cross-weld specimens

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INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 1996年第1-3期66卷 199-222页

作者： Segle, P Tu, ST Storesund, J Samuelson, LA Swedish Plant Inspection Ltd Box 49306 S-10029 Stockholm Sweden The Royal Institute of Technology Dept. of Materials Science and Engineering S-10044 Stockholm Sweden Nanjing Institute of Chemical Technology Dept. of Mechanical Engineering Nanjing 210009 P.R. China Swedish Institute for Metals Research Drottning Kristinas väg 48 S-114 28 Stockholm Sweden

In order to reduce production costs, it is of great interest to use longitudinal seam welds when manufacturing large diameter pipes. The cost reduction can be as high as 30%. However, severe inservice accidents for this type of pipes working in the creep regime have occurred mainly due to mismatch match in weldment creep properties. In many cases, creep tests of cross-weld specimens, taken from the seam weld, are used to predict the behaviour of the seam weld assuming that the creep behaviour of specimen and weldment is equivalent. Experiences of this procedure indicate that further knowledge is required before translation between specimen and component can be made. In the present paper, both full scale seam welded pipes and cross-weld specimens are studied with the damage mechanics concept using finite element, FE, technique. The same mechanical model of multiple material zones is used for the two components. Both the influence of differences in creep properties between the weldment constituents and the size effect of the cross-weld specimen, are studied. It is found that the cross-weld test results can not directly be translated to the full scale component. Factors such as the creep properties and the relative geometry of the weldment constituents and the size of the cross-weld specimen have to be considered when performing creep life assessment.

关键词： creep creep damage creep-hard creep-soft cross-weld life assessment mis-match seam weld size effect weld

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A COMPARISON OF PIECEWISE-LINEAR AND CONTINUOUS APPROXIMATING MODELS

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MECHANICS RESEARCH COMMUNICATIONS 1995年第6期22卷 527-532页

作者： BEGLEY, CJ VIRGIN, LN Dept. of Mechanical Engineering and Materials Science Duke University Durham N.C. USA

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CHEMICAL PRESSURE ANALYSIS OF HIGH-TEMPERATURE SUPERCONDUCTORS - ANISOTROPIC EFFECTS IN YBA2CU3O7-X AND YBA2(CU1-YFEY)3O7-X

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materials CHEMISTRY AND PHYSICS 1994年第3-4期36卷 343-349页

作者： COCKS, FH HAMMARSTROM, HM Duke University Dept. of Mechanical Engineering and Materials Science Durham NC 27708 USA

Quantitative evaluation of selected sets of critical temperature and lattice parameter data for the orthorhombic compounds YBa2CU3O7-x and YBa2(Cu1-yFey)3O7-x reveals a strongly anisotropic dependence of the critical temperature on these parameters, especially for YBa2Cu3O7-x. This method of deriving the relationship between critical temperature and changes in lattice constants is termed chemical pressure analysis (CPA). The signs of the anisotropic chemical pressure coefficients, k(i), for the critical temperature of YBa2Cu3O7-x are found to be opposite to those determined for anisotropically applied physical (mechanical) pressure and of greatly increased magnitude. One explanation for these differences may be that physical pressures do not alter chemical bonds in the same manner as do chemical pressures. For pressures below 4 GPa, both CPA and physical pressure results indicate that increasing hydrostatic pressure increases T(c), but chemical pressures are found to be more effective at increasing critical temperature than are physical pressures. Hydrostatic pressures above 4 GPa, however, decrease T(c). Since the fracture strength of real crystals limits the magnitude of the anisotropic physical stresses that can be applied, only CPA appears capable of yielding the anisotropic dependence of critical temperature on individual lattice parameters in the ultrahigh stress regime above 4 GPa.

关键词： High temperature superconductors

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