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  • JLA Vol:17 Iss:1 (Thermodynamics and laser material processing)


    Authors:
    W. W. Duley
    Physics Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1


    In many laser applications it is the conversion of photon energy to heat that drives the process. Heat transfer theory accurately describes the effects produced, and other aspects of thermodynamics need not generally be considered explicitly. The highly nonequilibrium nature of laser materials processing operations can usually be ignored once the heat transfer problem is defined. However, “equilibrium” is a concept that is basic to thermodynamics, and so it is useful to examine this concept in the context of traditional laser materials processing applications. Some of the ass...

    $25.00

  • JLA Vol:21 Iss:2 (Visualization of refraction and attenuation of near-infrared laser beam due to laser-induced plume)


    Authors:
    Yousuke Kawahito
    Keisuke Kinoshita
    Naoyuki Matsumoto
    Seiji Katayama
    Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan


    This study was performed to obtain a fundamental knowledge of the interaction between a near-infrared laser beam and an induced plume during welding. The plume was characterized by spectroscopy, and the effect and mechanism of the laser-induced plume on the refraction and/or attenuation were investigated by high-speed video observation of the plume and the probe laser, and power meter measurement of the fiber probe laser beam of 1090 nm wavelength which pa...

    $25.00

  • JLA Vol:8 Iss:1 (Frequency–time characteristics of air‐borne signals from laser welds)


    Authors:
    D. Farson
    K. Hillsley
    J. Sames
    R. Young



    The acoustic emissions from laser lap welds in stainless steel sheet were recorded and analyzed. The acoustic signals emanating from the weld were sensed with an instrument microphone and analyzed using short‐time Fourier spectra to characterize their time‐frequency distributions. It was determined that the acoustic spectrum of good‐quality, full‐penetration welds could be differentiated from the spectra of poor‐quality welds, defined as either partial‐penetration welds or welds having a gap between the sheets being joined. A novel, relatively simple class...

    $25.00

  • JLA Vol:15 Iss:1 (Dual laser beam modification of high alumina ceramics)


    Authors:
    D. Triantafyllidis
    Array

    J. R. Bernstein
    Corrosion and Protection Centre, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom

    L. Li
    Department of Mechanical, Aerospace and Manufacturing Engineering, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom

    F. H. Stott
    Corrosion and Protection Centre, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom


    Alumina-based refractory materials are extensively used in high-temperature applications, such as linings in waste incinerators. A sign...

    $25.00

  • JLA Vol:19 Iss:2 (Femtosecond laser microstructuring of hot-isostatically pressed zirconia ceramic)


    Authors:
    Niko Ba¨rsch
    Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover, Germany

    Kristian Werelius
    Department of Prosthodontics, Johann Wolfgang Goethe University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany

    Stephan Barcikowski
    Fernando Liebana
    Uwe Stute
    Andreas Ostendorf
    Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover, Germany


    Densely sintered zirconia ceramics—especially hot-isostatically pressed forms of zirconia ceramics like hot-isostatically pressed yttria-stabilized tetragonal zirconia polycrystal (HIP Y-TZP)—have the potential of superseding conve...

    $25.00

  • JLA Vol:24 Iss:2 (Synthesis of nitrogen-doped diamond films using vibrational excitation of ammonia molecules in laser-assisted combustion flames)


    Authors:
    L. S. Fan
    Z. Q. Xie
    J. B. Park
    X. N. He
    Y. S. Zhou
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511

    L. Jiang
    Department of Mechanical and Automation Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China

    Y. F. Lu
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511


    Nitrogen-doped diamond was synthesized in open air using laser-assisted combustion flame method. A wavelength-tunable CO2 laser was used to resonantly excite the vibration mod...

    $25.00

  • JLA Vol:6 Iss:3 (Acoustic emission response of soda lime glass after a single Nd‐YAG laser pulse)


    Authors:
    R. Harrysson
    P. Vomacka
    Department of Engineering Materials, Luleå University of Technology, S‐951 87 Luleå, Sweden


    When machining brittle solids with a laser, crack formation can occur in the material around the irradiated area causing a strength reduction of the machined material. The purpose of this work was to study a well known brittle material (soda lime glass) by means of acoustic emission (AE) in order to investigate the correlation between visually observed crack formation and detected AE energy released by the crack formation in the material. During and after irradiation of soda lime glass with an Nd‐YAG laser pulse, the number...

    $25.00

  • JLA Vol:25 Iss:3 (Surface pore initiated fatigue failure in laser clad components)


    Authors:
    M. M. Alam
    J. Powell
    A. F. H. Kaplan
    Department of Engineering Science and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

    J. Tuominen
    P. Vuoristo
    Department of Materials Science, Tampere University of Technology, FI-33101 Tampere, Finland

    J. Miettinen
    J. Poutala
    Department of Mechanics and Design, Tampere University of Technology, FI-33101 Tampere, Finland

    J. Na¨kki
    Department of Materials Science, Tampere University of Technology, FI-33101 Tampere, Finland and Technology Centre KETEK Ltd, FI-67100 Kokkola, Finland

    J. Junkala

    $25.00

  • JLA Vol:17 Iss:4 (Effect of steel composition on the laser cutting behavior of 25-mm-thick plates)


    Authors:
    M. Manohar
    R. L. Bodnar
    Mittal Steel USA R&D, Bethlehem, Pennsylvania

    R. I. Asfahani
    U.S. Steel Research and Technology Center, Monroeville, Pennsylvania

    N. Chen
    C. Huang
    Caterpillar Technical Center, Peoria, Illinois


    Attempts were made to gain a better understanding of the effects of steel composition and thermophysical properties, such as solidus and liquidus temperatures, heat of oxidation, surface tension, viscosity and thermal conductivity, on laser-cutting behavior. Laboratory-produced heats containing varying levels of C, S, Si, Cu, Ni, Cr, and Mo were hot-rolled to 32-mm-thick plates. Laser cutt...

    $25.00

  • JLA Vol:22 Iss:1 (Surface effects of alumina ceramics machined with femtosecond lasers)


    Authors:
    J. Meeker
    A. E. Segall
    V. V. Semak
    Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802


    Laser machining is now an accepted method for shaping and modifying ceramics and is rapidly replacing other methods such as grinding and etching. In fact, new innovations such as short pulsed or femtosecond lasers have drastically decreased the amount of unwanted damage associated with laser machining. However, laser machining does still alter the surface and can change the flaw populations and the strength. In order to investigate this effect, the flaw populations and strengths of both unaltered and femtosecond...

    $25.00

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