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

    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...


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

    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...


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

    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...


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

    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...


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

    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...


  • JLA Vol:8 Iss:5 (Diode‐pumped Nd:YAG laser for precision laser machining)

    Jason Machan
    Marcy Valley
    Gerry Holleman
    Marc Mitchell
    Dave Burchman
    Jim Zamel
    George Harpole
    Hagop Injeyan
    Len Marabella
    TRW R1/1184, One Space Park, Redondo Beach, CA 90278, U.S.A.

    Results are presented on a high power, diode‐pumped, pulsed Nd:YAG laser for precision laser machining. The laser is an unstable resonator with a graded reflectivity outcoupler, generating a beam with excellent beam quality. The gain medium is a single zig‐zag slab, pumped symmetrically by diode arrays. The use of diode arrays minimizes the thermal loading on the slab, and the zig...


  • JLA Vol:2 Iss:1 (The Energy Transfer Efficiency in Laser Welding Process)

    T. H. Kim
    Charles E. Albright
    Schichan Chiang
    Department of Welding Engineering, The Ohio State University, 190 W. 19th Ave., Columbus, Ohio 43210

    The process efficiency of laser beam welding was measured as a function of travel speed. Temperature measurements were carried out during the bead‐on‐plate laser welding of mild steel with a focused 2KW CO2 laser beam at various welding travel speeds. The laser welding process efficiency (power delivered to work/power in the beam) was calculated from the ratio of the heat content of the welded the specimen to the available laser beam energy (power × time). In the deep penetr...


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

    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


  • JLA Vol:5 Iss:1 (Single Pass Laser Cutting of Polymers)

    R. Patel
    G. Baisch
    IBM Corporation, GTD, Hopewell Junction, New York

    Since the early 1980's discovery of the ability of excimer lasers to etch polymers precisely and cleanly with minimal thermal damage, excimer lasers have been used actively in the semiconductor industry for various manufacturing processes. In the present study a process for laser cutting of polymers has been investigated. A laser beam of controlled cross‐sectional shape is imaged onto a polymer surface. The geometry of the cutting path is controlled by precise movement of a sample mounted on a 2‐axis computer controlled work stage. This type of a process is useful for applications ...


  • JLA Vol:14 Iss:1 (Multiple reflection and its influence on keyhole evolution)

    Hyungson Ki
    Pravansu S. Mohanty
    Jyotirmoy Mazumder
    Center for Laser Aided Intelligent Manufacturing, Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 48109-2125

    In laser drilling and keyhole welding, multiple reflection phenomena determine how the energy is transferred from the laser beam to the workpiece, and, most importantly, all other physics such as fluid flow, heat transfer, and the cavity shape itself depend on these phenomena. In this study, a multiple reflection model inside a self-consistent (or self-evolving) cavity has been developed based on the level set method and ray tracing t...



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