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Characterization of AL-Y alloy thin films deposited by direct current magnetron sputtering

Journal of Vacuum science & Technology B: Microelectronics Processing and Phenomena 1997年第6期15卷 1990-1990页

作者： Liu, Y. Singh, R. Poole, K. Diefendorf, R.J. Harriss, J. Cannon, K. Materials Science and Engineering Program Clemson University Clemson South Carolina 29634 Department of Electrical and Computer Engineering Materials Science and Engineering Program Clemson University Clemson South Carolina 29634 Department of Ceramic Engineering and Materials Science and Engineering Program Clemson University Clemson South Carolina 29634 Department of Electrical and Computer Engineering Clemson University Clemson South Carolina 29634 Cryovac North America W. R. Grace & Co. Duncan South Carolina 29334

Thin films of Al-1.27 wt %Y were deposited by dc magnetron sputtering. Adding yttrium to the aluminum drastically reduced the metal’s grain size and also improve the uniformity of grain size distribution. Upon annealing at a temperature of 450 °C for 30 min, grain growth was insignificant, while the electrical resistance dropped from 6.05 to 2.95 μΩ cm. The as deposited films consisted of Al4Y and α-Al supersaturated with yttrium. After annealing, β-Al3Y precipitated instead of α-Al3Y. The Al–Y films had much higher resistance to hillock formation than did Al-1 wt %Si films.

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Tensile strength of high speed proof tested fiber optics

Tensile strength of high speed proof tested fiber optics

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SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics (IMOC)

作者： G.M. Camilo J. Matthewson Departamento Acadêmico de Mecânica CEFET Paraná Curitiba Parana Brazil Fiber Optics Materials Research Program Department of Ceramic Science and Engineering Rutgers University Piscataway NJ USA

Using the "Statistical Theory of Fracture for Brittle Materials" and performing tests for long lengths of fibers at distinct proof stresses and different velocities, the performance of a high velocity test machine and detected level of damage in the fiber samples, are assessed. To confirm the damage and to know the strength of the fiber samples after proof tests, tensile tests were performed.

关键词： Optical fiber testing Optical fibers Optical fiber devices Optical fiber theory Optical materials ceramics Performance evaluation Optical device fabrication Materials testing Tensile stress

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NONLINEAR HERTZIAN INDENTATION FRACTURE-MECHANICS

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JOURNAL OF THE AMERICAN ceramic SOCIETY 1995年第9期78卷 2321-2327页

作者： BURNS, SJ CHIA, KY Materials Science Program Department of Mechanical Engineering University of Rochester Rochester New York 14627–0133 Member American Ceramic Society. Standard Ceramics Inc. Alfred New York 14802–0848.

Indentation cracking under blunt indenters is analyzed using nonlinear fracture mechanics. The usual assumptions of linear elastic fracture mechanics have been replaced with a nonlinear load vs load-point displacement curve while assuming the material is linear elastic, The load, the load-point displacement, and a function of the crack area have been related to the crack driving force, J, while assuming a cone fracture under the Hertzian sphere, Experimentally, it was found that the load-displacement curve during loading, cracking, and unloading is nonlinear. The crack length is empirically shown to be proportional to the load-point displacement for several indenters, The experimentally measured relations between indenter load, load-point displacement, and crack geometries are then analyzed with mechanical energy balances based on the similitude of crack lengths with load-point displacements. The Hertz hardness that describes the nonlinear load vs load-point displacement relation during cracking is derived on the constant J line in load-displacement space. Finally, well-known experimental expressions that relate load to crack length are shown to be indistinguishable from the load-point displacement analysis reported.

关键词： Fracture mechanics

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NONLINEAR COMPLIANCE TESTING APPLIED TO INDENTATION CRACKING IN ceramicS

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JOURNAL OF THE AMERICAN ceramic SOCIETY 1995年第9期78卷 2328-2334页

Indentation cracking under sharp-pointed indenters is analyzed using compliance-based, nonlinear, fracture mechanics, The stress intensity factor, K, in linear elastic fracture mechanics is well known to be proportional to the load, P;in this nonlinear analysis K is proportional to P-3/4. The observed relation between indenter load-point displacement and crack length is based on similitude of crack lengths with load-point displacements as a strain-controlled fracture. The equations that relate load and a function of the crack length to the crack driving force, J, have been found for Vickers indentations. Analysis of the nonlinear load vs displacement assumes an equilibrium crack in the elastic material surrounding the indent, The hardness that describes the load vs load-point displacement during cracking is derived on a constant J line in load-displacement space. The crack length is shown experimentally to be proportional to the load-point displacement after crack initiation for several different indenters in ZnS. The measured loading curves are nonlinear and display crack initiation during loading, The K-Ic expressions found here are very similar to correlations that have been applied to indentation cracks.

关键词： ceramic materials

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EFFECT OF LOADING MODE AND COATING ON DYNAMIC FATIGUE OF OPTICAL-FIBER IN 2-POINT BENDING

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JOURNAL OF THE AMERICAN ceramic SOCIETY 1993年第1期76卷 139-144页

作者： RONDINELLA, VV MATTHEWSON, MJ Fiber Optic Materials Research Program Department of Ceramic Science and Engineering Rutgers University

Two-point bending is a useful method for investigating the mechanical properties of optical fiber and has several advantages when compared to the traditional tensile test. However, the strength of the fiber is usually determined at constant faceplate velocity rather than at constant strain rate as in the uniaxial tensile test, and previous work casts doubt on the comparability of fatigue results obtained using different loading modes and hence on the reliability of the bending technique. This paper presents dynamic fatigue results using a two-point bend apparatus that can be programmed to operate in constant velocity, constant strain rate, and constant stress rate loading modes. These results, obtained for both bare and polymer-coated fused silica optical fiber, show no significant differences in the calculated fatigue parameters for the three loading modes and clearly indicate the reliability of the two-point bend method at constant faceplate velocity. The results, however, show that the obtained value of the stress corrosion susceptibility parameter, n, is dependent on the quantity used to define it, i.e., stress or strain to failure, because of the nonlinear elastic behavior of silica.

关键词： .constant strain loading modes constant stress

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INFLUENCE OF AMORPHOUS GRAIN-BOUNDARY PHASES ON THE SUPERPLASTIC BEHAVIOR OF 3-MOL-PERCENT-YTTRIA-STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS (3Y-TZP)

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JOURNAL OF THE AMERICAN ceramic SOCIETY 1993年第7期76卷 1681-1690页

作者： GUST, M GOO, G WOLFENSTINE, J MECARTNEY, ML Materials Science and Engineering Program Department of Mechanical and Aerospace Engineering University of California Irvine California 92717 Member American Ceramic Society.

Amorphous silicate grain boundary phases of varying chemistry and amounts were added to 3Y-TZP in order to determine their influence on the superplastic behavior between 1200-degrees and 1300-degrees-C and on the room-temperature mechanical properties. Strain rate enhancement at high temperatures was observed in 3Y-TZP containing a glassy grain boundary phase, even with as little as 0.1 wt% glass. Strain rate enhancement was greatest in 3Y-TZP with 5 wt% glass, but the room-temperature hardness, elastic modulus, and fracture toughness were degraded. The addition of glassy grain boundary phases did not significantly affect the stress exponent of 3Y-TZP, but did lower the activation energy for superplastic How. Strain rate enhancement was highest in samples containing the grain boundary phase with the highest solubility for Y2O3 and ZrO2, but the strain rate did not scale inversely with the viscosity of the silicate phases. Grain boundary sliding accommodated by diffusional creep controlled by an interface reaction is proposed as the mechanism for superplastic deformation in 3Y-TZP with and without glassy grain boundary phases.

关键词： ceramic materials

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FUEL-CELL POWER-PLANTS FOR SURFACE FLEET APPLICATIONS

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NAVAL ENGINEERS JOURNAL 1994年第3期106卷 59-76页

作者： GOUBAULT, P GREENBERG, M HEIDENREICH, T WOERNER, J Philippe Goubault:graduated in 1983 from the “Ecole Nationale Superieure de Techniques Avancees” in Paris with a major in naval architecture. After one year of military service with the French navy he worked as naval architect and program director for the French navy between 1984 and 1988. He was in charge of the development of AGNES200 Surface Effect Ship design which completed its sea trials in 1992. He also was responsible for the construction of five ships (four hydrographic vessels and one experimental MCM vessel) which entered service between 1988 and 1991. He has been involved in a number of projects and studies for the U.S. Navy U.S. Coast Guard and other foreign and domestic customers. At Band Lavis & Associates Inc. Mr. Goubault has expanded the computer tools used to conduct parametric analysis of advanced hullforms and has developed cost-effectiveness assessment tools and methodologies for both commercial and military ships. Mr. Goubault is a member of ASNE. Marc Greenberg:is employed as a cost analyst at the cost and economic analysis branch systems assessment and engineering division Naval Surface Warfare Center. He provides cost estimates and analyses of Navy ship and submarine technologies and has assisted in the development of parametric cost models since 1991. Employed as an electronics engineer by the U.S. Army Information Systems Command from 1989 to 1991 he provided support in simulation design and construction of high frequency and microwave communication systems. Mr. Greenberg received his BS degree in ceramic science and engineering from the Pennsylvania State University May 1987. He is a member of MORS. Todd Heidenreich:is employed in the design analysis and tools branch systems assessment and engineering division of the Carde-rock Division Naval Surface Warfare Center. He is involved as a project naval architect in the conceptual design of future surface ship designs future technology impact assessments and the assessment of current domestic and foreign surface ship desig

This paper describes the results of a study undertaken to determine the impact of fuel cell technology on the design and effectiveness of future naval surface combatants. The study involved the collection of data to characterize four different fuel cell technologies: proton exchange membrane, molten carbonate, phosphoric acid, and solid oxide fuel cells. This information was used to expand current computer models to develop specific fuel cell plants that met the power requirements for several applications on a nominal 5000 Lton destroyer and a nominal 2000 Lton corvette. Each of the fuel cell technologies was incorporated into several applications aboard the destroyer and the corvette. These applications included combinations of centralized and distributed ship service power, and propulsion power. In addition, the impact of fuel cell technology was determined for a ship service power backfit option aboard a DDG-51 class destroyer. The results of the impact on the ship designs were analyzed and a military effectiveness assessment was conducted to address such issues as the impact of fuel cells on mobility, survivability, affordability, and on the environment. The paper identifies which aspects of the fuel cell technologies have the greatest impact upon the ship designs and their operational costs. Recommendations are given for future technology development efforts required to make fuel cells suitable for Navy service.

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Optical fiber mechanical testing techniques

Optical fiber mechanical testing techniques

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Fiber Optics Reliability and Testing: A Critical Review 1993

作者： John Matthewson, M. Rutgers Univ. Fiber Optic Materials Research Program Department of Ceramic Science and Engineering PiscatawayNJ08855 United States

This paper reviews the common techniques for mechanical testing of optical fiber specimens and compares and contrasts their attributes. Any technique must be able to grip the specimens without causing failure at the grips. The techniques generally fall into two categories;uniaxial tensile testing in which the fibers must be gripped carefully, and bending techniques which reduce the local stress at the grips. The former techniques generally give results that are easier to interpret due to the homogeneous stress field but are experimentally the least convenient. In contrast, bending techniques are experimentally convenient, but due to the inhomogeneous nature of the stress field developed and the short fiber test lengths, may not be as useful as tension for some purposes. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Tensile testing

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Optical fiber reliability models

Optical fiber reliability models

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Fiber Optics Reliability and Testing: A Critical Review 1993

作者： John Matthewson, M. Rutgers Univ. Fiber Optic Materials Research Program Department of Ceramic Science and Engineering PiscatawayNJ08855 United States

Systems containing optical fiber have design lives on the order of decades so that models for assessing the mechanical reliability of the fiber must rely on extrapolations from accelerated short term testing. Such extrapolations are only valid if all relevant mechanisms are fully understood. The physical processes giving rise to mechanical degradation are reviewed and it is shown that no single model describes all situations. In particular, strong "pristine" fiber can behave quite differently from weaker fiber. Additionally, two degradation regimes are identified, one which is stress assisted (fatigue) and one which can occur even in the absence of applied stress (aging). Recent advances in understanding these phenomena are discussed and promising areas for future work are proposed. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Optical fibers

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THE INFLUENCE OF SOLUBILITY ON THE RELIABILITY OF OPTICAL FIBER

THE INFLUENCE OF SOLUBILITY ON THE RELIABILITY OF OPTICAL FI...

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CONF ON OPTICAL MATERIALS AND TESTING : BENIGN AND ADVERSE ENVIRONMENTS

作者： MATTHEWSON, MJ RONDINELLA, VV KURKJIAN, CR Rutgers University Fiber Optic Materials Research Program Department of Ceramic Science and Engineering Piscataway 08855 NJ United States ATandT Bell Laboratories 600 Mountain Avenue Murray Hill 07974 NJ United States

ISBN: (纸本)0819409707

Recent advances in the understanding of reliability of silica optical fiber indicate that the chemical durability of the fiber can control the long duration lifetime both under stress-induced fatigue and zerostress aging conditions. In particular, dissolution of surface material produces strength degrading surface roughness. These mechanisms are discussed and strategies for improving reliability by inhibiting dissolution are examined. As an example, a modified polymer coating formulation is described that is shown to increase the lifetime of the fiber by up to a factor of thirty-fold. Strategies for improving the strength and durability of non-oxide fibers using a similar approach are also discussed. © 1993 SPIE. All rights reserved.

关键词： Optical fibers

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