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

Authors:
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:25 Iss:4 (On the exposure limits for extended source multiple pulse laser exposures)

JLA Vol:19 Iss:3 (Femtosecond pulsed laser microfabrication of SiC MEMS microgripper)

Authors:
Monica Vendan
Pal Molian
Mechanical Engineering Department, Iowa State University, Ames, Iowa 50011

We report the capability of an ultrafast laser to pattern an electrostatic-comb-drive microgripper in the chemically difficult-to-etch 3C-SiC thin films. A microgripper with overall dimensions 1.2 mm×0.35 mm and a gap of 20 μm was designed and fabricated for the purpose of grasping and transporting microscale objects in hostile and harsh environments. Atmospheric pressure chemical vapor deposition was used to deposit thin films (∼2 μm) of 3C-SiC on 〈100〉 silicon substrates. A Ti:sapphire laser with 120 fs pulse wid...

JLA Vol:24 Iss:3 (Laser cladding for railway repair and preventative maintenance)

Authors:
Adam Clare
Olusola Oyelola
Janet Folkes
Peter Farayibi
Innovative Manufacturing Processes Group, Manufacturing Division, Faculty of Engineering, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom

Rolling contact fatigue, amongst other mechanisms of wear, between railway track and train wheel ensures that periodic replacement of worn track and other key components such as switches must be undertaken. The cost associated with repairing/replacing track is significant. This places a financial burden upon the rail network provider, creates a significant carbon footprint associated with remanufacture of track, an...

JLA Vol:6 Iss:4 (Erratum: Excimer laser processing of Ti–6Al–4V)

Authors:
J. A. Folkes
K. Shibata
Nissan Motor Co. Ltd, Materials Research Laboratory, Central Engineering Laboratories, 1, Nasushima‐cho, Yokosuka 237, Japan

JLA Vol:18 Iss:1 (Effect of oxygen in ambient atmosphere on penetration characteristics in single yttrium–aluminum–garnet laser and hybrid welding)

Authors:
Yasuaki Naito
Masami Mizutani
Seiji Katayama
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Welding with a yttrium–aluminum–garnet (YAG) laser only or with hybrid source combined with a YAG laser and a TIG arc was carried out on Type 304 stainless steel plate with low S content in the air or in the chamber with Ar gas including 0%–15% oxygen gas. It was confirmed in both laser and hybrid welding that the penetration and geometry of welds depended upon the volume of the oxygen in the ambient atmosphere, and that a pronounced “nail head” disappeared in a weld...

JLA Vol:22 Iss:3 (Evaluation criterion and closed-loop control of penetration status during laser-MIG hybrid welding)

Authors:
Yongqiang Zhang
Shougang Research Institute of Technology, Beijing 100043, Peoples Republic of China

Peng Wen
Jiguo Shan
Yuanqing Shuang
Wuzhu Chen
Department of Mechanical Engineering, Tsinghua University Beijing 100084, Peoples Republic of China

Laser-MIG hybrid welding is an advanced joining process and is widely applied in various industries. It is important to make sure the plate is fully penetrated with an appropriate weld formation in practical applications. In this paper, 3 kW CO₂ laser and pulse MIG machine were used to compose the laser-MIG hybrid welding equipment to make butt weld of stainless...

JLA Vol:8 Iss:6 (Laser surface alloying of magnesium base alloys)

Authors:
R. Galun
A. Weisheit
B. L. Mordike
Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Universita¨t Clausthal, Agricolastraße 6, D‐38678 Clausthal‐Zellerfeld, Germany

The feasibility of the laser surface alloying of magnesium base alloys with aluminum, copper, nickel and silicon has been shown in this work. By laser alloying with these elements, using a 5 kW CO₂‐laser, the hardness of several magnesium base alloys can be increased to values above 250 HV_0.1. Melted depths from 700–1200 μm and alloying contents from 15–55 at % were achieved. The wear resistance of ...

JLA Vol:1 Iss:4 (Optical Methods in Flow Visualization)

Authors:
Wen‐Jei Yang
Yi Chen
Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 48109

Optical techniques for flow visualization are presented, including light‐sheet flow visualization, shadowgraphy, schlieren method, interferometry, holography, speckle photography, laser‐induced fluorescence and thermography. The principles of these methods are briefly described and the examples of their applications to flow visualization are given.

JLA Vol:16 Iss:1 (Laser-induced electrochemical characteristics of aluminum alloy 2024-T3)

Authors:
Olga Kachurina
Tammy L. Metroke
Kai Dou
Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078

Laser-induced surface modification of aluminum alloy 2024-T3 was investigated as laser intensity dependence of surface composition and patterning related to electrochemical characteristics using techniques of environmental scanning electron microscopy (ESEM), potentiodynamic scan, and electrochemical impedance spectroscopy (EIS). Analysis of surface composition using ESEM and EIS indicated that laser fluences in a range of 1.1–1.3 J/cm² were found to preferentially reduce the copper concentration in the alloy surf...