• JLA Vol:15 Iss:2 (Laser surface processing of titanium in air: Influence of scan traces overlapping)

    A. Pe´rez del Pino
    P. Serra
    J. L. Morenza
    Departament de Fı´sica Aplicada i Òptica, Universitat de Barcelona, E-08028 Barcelona, Spain

    Laser surface treatments of titanium in air have been performed through a pulsed Nd:yttrium–aluminum–garnet (λ=1.064 μm) laser. Several samples have been obtained modifying the laser scan velocity and partial overlapping of consecutive traces, in order to study the influence of these parameters on the surface morphology. Scanning electron microscopy and profilometry measurements have revealed different surface morphologies depending on the physical processes involved in th...


  • JLA Vol:15 Iss:2 (Optimization and modeling of laser forming of stainless steel circular sectors)

    G. Casalino
    A. D. Ludovico
    Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, Bari 70126, Italy

    Mold-less forming produces precise metal parts by thermal variation generated used high power beam irradiation. Some technologies like the laser and the plasma arc have proved to fit the requirements of this new forming technique [M. Geiger and F. Vollersten, Ann. CIRP 42, 301–304 (1993); P. J. Li et al., J. Eng. Manuf. Proc. Part B 214, 0954–4054 (2000)], which can be applied both for rapid prototyping and rapid manufacturing. In particular, a complex shape can be generated using curved path for the irradiating strategy o...


  • JLA Vol:15 Iss:2 (Plasma assisted laser surface alloying)

    M. H. McCay
    C. M. Sharp
    J. A. Hopkins
    The Center for Laser Applications, The University of Tennessee Space Institute, Tullahoma, Tennessee 37388

    B. Szapiro
    The Department of Physics, University of the South, Sewanee, Tennessee

    T. D. McCay
    The Center for Laser Applications, The University of Tennessee Space Institute, Tullahoma, Tennessee 37388

    The combination of plasma arc with a Nd:YAG laser during surface alloying produces a synergistic effect which significantly increases the depth of the melt pool beyond that expected by a summation of the individual depths. Incremental increases in laser power produce ...


  • JLA Vol:15 Iss:3 (Continuous wave laser ignition thresholds of coal dust clouds)

    Thomas H. Dubaniewicz
    Kenneth L. Cashdollar
    Gregory M. Green
    National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, Pennsylvania 15236

    Laser-based instruments are used in areas where coal dust ignition presents a safety hazard. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory (NIOSH, PRL) is conducting a study to help determine when an optical beam may be considered a potential ignition source in underground coal mines or coal storage facilities. Researchers conducted experiments to determine threshold igniting powers for Pittsburgh seam bituminous co...


  • JLA Vol:15 Iss:3 (Control of chaos in laser-induced vapor capillaries)

    M. H. Cho
    D. F. Farson
    Welding Engineering Department, The Ohio State University, Columbus, Ohio 43221

    J. I. Kim
    The Faculty of Marine Engineering, Mokpo National Maritime University, Mokpo, Chonnam 530-729, Korea

    Vapor capillaries associated with deep penetration laser welding (keyholes) are inherently unstable and it is well known that the bounded evolution of unstable modes of nonlinear dynamic systems can lead to complex fluctuations of state and/or output variables. In the case of keyholes, the magnitude of self-induced fluctuations is sometimes large enough to cause occasional closure (“collapse”) and trapping of voids in t...


  • JLA Vol:15 Iss:3 (Do <em>in vivo</em> terahertz imaging systems comply with safety guidelines?)

    Elizabeth Berry
    Gillian C. Walker
    Anthony J. Fitzgerald
    Academic Unit of Medical Physics and Centre of Medical Imaging Research, University of Leeds, Wellcome Wing, Leeds General Infirmary, Leeds LS1 3EX, United Kingdom

    N. N. Zinov’ev
    Martyn Chamberlain
    Institute of Microwaves and Photonics, University of Leeds, Leeds LS2 9JT, United Kingdom

    Stephen W. Smye
    Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, St. James’s University Hospital, Leeds LS9 7TF, United Kingdom

    Robert E. Miles
    Institute of Microwaves and Photonics, University of Leeds, Lee...


  • JLA Vol:15 Iss:3 (Experimental and numerical analyses of the mechanism for decreasing hydrogen-embrittlement sensitivity of aged Inconel 718 by laser surface annealing)

    Liufa Liu
    School of Materials Science and Engineering, Shanghai Jiao Tong University, Huashan Road 1954, Shanghai 200030, China

    Katsumi Tanaka
    Akio Hirose
    Kojiro F. Kobayashi
    Department of Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

    Laser surface annealing (LSA) treatments were conducted to decrease the hydrogen embrittlement (HE) sensitivity of Inconel 718. Hydrogen was charged into the alloy by a cathodic-charging process. The LSA treatment significantly reduced the strength loss of the hydrogen-precharged notched specimen. Tensile tests and elasto–...


  • JLA Vol:15 Iss:3 (Hole drilling of Inconel 718 by high intensity pulsed ultraviolet laser)

    Qihong Wu
    Yurong Ma
    Jiansheng Jie
    Qingxuan Yu
    Yuan Liao
    Rongchuan Fang
    Department of Physics, Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui, 230026, People’s Republic of China

    Xiangli Chen
    Kelvin Wang
    GE Corporate Research and Development Shanghai Center, 421 Hongcao Road, Shanghai 200233, People’s Republic of China

    Holes were percussion drilled in Inconel 718 plates by a high intensity pulsed ultraviolet laser (266 and 355 nm) with 8 ns pulse width. It showed that shortening the laser wavelength resulted in thinner recas...


  • JLA Vol:15 Iss:3 (Preparation of polyperinaphthalenic organic semiconductive nanoparticles by excimer laser ablation and their application to optic and electronic devices)

    Satoru Nishio
    Hiroshi Fukumura
    Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Sendai, Miyagi 980-8578, Japan

    Kazuyuki Tamura
    Jun Murata
    Junko Kitahara
    Teruhiko Kan
    Akiyoshi Matsuzaki
    Department of Chemistry for Materials, Faculty of Engineering, Mi’e University, 1515 Kamihama-cho, Tsu, Mi’e 514-8507, Japan

    Nobuo Ando
    Yukinori Hato
    Kanebo LTD., 3-1, Kanebo-cho, Hofu, Yamaguchi 747-0823, Japan

    Polyperinaphthalene (PPN) nanoparticles are prepared by excimer laser ablation (ELA) of a 3, 4, 9, 10-perylenetetracarbox...


  • JLA Vol:15 Iss:3 (Process characteristics and effects of gas- and water-atomized stainless steel powders in laser-based rapid tooling)

    Andrew J. Pinkerton
    Lin Li
    Department of Mechanical, Aerospace, and Manufacturing Engineering, Laser Processing Research Centre, UMIST, P.O. Box 88, Sackville Street, Manchester M60 1QD, United Kingdom

    In rapid tooling using the direct laser deposition process and stainless steel materials, only powders prepared using the gas-atomization method have been used because of their presumed superior flow characteristics. In this article, the use of water-atomized powder is investigated by comparing the behavior of the two types of 316 L powders, deposited using a CO2 laser and coaxial head. Results show little difference in the pneumatic conveyance of the po...



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