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  • 1
    Electronic Resource
    Electronic Resource
    Diffusion-limited layer growth in spherical geometry: A numerical approach (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4350-4353 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article we present a detailed numerical analysis of the problem of diffusion-controlled growth of a solid intermediate phase from two saturated solutions (solid solute and solid or liquid solvent). Spherical geometry is considered and the quasi-steady-state approximation used in earlier analytical models is eliminated. Comparison between our results and those from Larson's model allows us to conclude that the use of a numerical scheme may lead to a significant gain in accuracy except when a solute-rich sphere is converting into a dilute phase. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363392
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  • 2
    Electronic Resource
    Electronic Resource
    Laser surface treatment of tool steels (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 1273-1289 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Laser surface treatment is a promising technique for improving the wear and corrosion resistance of materials. In the case of tool steels, laser surface treatment is preferably carried out in the liquid state to allow for complete dissolution of carbides. This paper concerns the application of laser melting to the surface treatment of AISI 420 and 440C martensitic stainless steels and sintered AISI T15 high-speed steel. Usually, laser-melted tool steels contain martensite, retained austenite and carbides. In steels containing large proportions of ferrite-forming alloying elements, δ-ferrite may also be observed. When applied to sintered steels, laser treatment leads to the elimination of residual porosity. The proportion of retained austenite in laser-melted steels is much higher than in conventionally treated steels. However, the hardness is high because austenite is strengthened by solid solution, dislocations and small grain size. The high volume fraction of retained austenite usually prohibits the application of tool steels in the laser-treated condition. Austenite may be eliminated by multiple tempering treatments at temperatures in the range 550–650°C. During tempering, carbides precipitate within austenite and martensite, and austenite transforms to martensite on cooling or isothermally to ferrite. Strong secondary hardening is often observed and the temperature of the secondary hardening peak of laser-surface-melted steels is higher than after conventional heat treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326481
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  • 3
    Electronic Resource
    Electronic Resource
    Estimation of required parameters for detection of small smoke plumes by lidar at 1.54 μm (2000)
    Springer
    Applied physics 71 (2000), S. 225-229 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 42.68.Wt; 92.60.Mt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Parameters of eyesafe lidar at 1.54 μm for detection of small plumes of smoke from burning wood or oil have been evaluated. It was assumed that a diode-pumped solid-state Er:glass laser at 1.54 μm or a Nd:YAG laser with a Raman cell or optical-parametric oscillator is used as a light source and that detection of backscattered light is performed with an avalanche photodiode. Ash and soot particle size distributions were taken from experiments. A backscattering coefficient at 1.54 μm for various source of smoke was estimated. In computing the laser energy, range between lidar and smoke, receiver optics diameter, fuel mass burned in unit time, fire source radius, laser pulse duration and visibility were varied. Results of the computations enabled estimation of the required laser energy, which ranges from 0.05 to 1400 mJ depending on the parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400000295
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  • 4
    Electronic Resource
    Electronic Resource
    Versatile reactor for LVCD large films production
    Amsterdam : Elsevier
    Vacuum 39 (1989), S. 861 
    Details
    ISSN: 0042-207X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0042-207X(89)90061-4
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  • 5
    Electronic Resource
    Electronic Resource
    CO"2 laser induced CVD of TiN
    Amsterdam : Elsevier
    Applied Surface Science 54 (1992), S. 130-134 
    Details
    ISSN: 0169-4332
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0169-4332(92)90032-S
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  • 6
    Electronic Resource
    Electronic Resource
    Electrochemical studies of laser-treated Co-Cr-Mo alloy in a simulated physiological solution (1994)
    Springer
    Journal of materials science 5 (1994), S. 353-356 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The aims of this work were to study the crevice corrosion resistance of laser-treated Co-Cr-Mo alloy by electrochemical techniques and to characterize the electronic properties of the passivating films. Open-circuit experiments and cyclic polarizations with crevice-free samples have been carried out as well as electrochemical impedance spectra using Bode-Nyquist and Mott-Schottky techniques. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis have been used in order to evaluate surface modifications. It has been observed that laser-treated Co-Cr-Mo alloy shows good corrosion resistance in spite of some degradation at the dendrites formed during treatment. By XPS it was found that at 6–9 nm depth there exists an enrichment in oxygen and a decrease of Cr which could have a slight effect on the corrosion resistance and it was seen that the film is mostly formed by Cr2O3. Mott-Schottky plots show that a possible transition from n-type to p-type semiconductivity may have occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058962
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  • 7
    Electronic Resource
    Electronic Resource
    Hardness anomalies on Cr 1−x Fe x (0.05〈x〈0.323) alloys: Mössbauer effect study (1990)
    Springer
    Hyperfine interactions 60 (1990), S. 919-922 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The hardness of Cr1-xFex α solid solutions presents an anomalous behaviour in the range 0.10〈xFe〈0.30, that has been explained either by magnetic or electronic effects. In order to verify wether the anomalies were intrinsic to that phase or were induced by impurities, measurements of microhardness and isomer shift of samples of high purity Cr1-xFex α solid solutions (0.05〈xFe〈0.323) were carried out. We found that the hardness presents a maximum and a minimum for xFe-0.19 and xFe-0.17, respectively, which are inferior to the amplitudes of the anomalies found by previous authors using lower purity alloys. Within the limit of experimental error, the isomer shift at room temperature varies linearly with the composition. These results suggest that impurities play a major role in determining the magnitude of the hardness anomalies and that electron transfer varies smoothly in the concentration range studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399901
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  • 8
    Electronic Resource
    Electronic Resource
    Structure and morphology of titanium nitride films deposited by laser-induced chemical vapour deposition (1994)
    Springer
    Journal of materials science 29 (1994), S. 404-411 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Results on the deposition of titanium nitride on AISI M2 tool steel-type substrates by pyrolytic laser chemical vapour deposition are reported. Spots of TiN were deposited from a gas mixture of TiCl4, nitrogen and hydrogen using a continuous wave quasi-TEMoo CO2 laser beam. The morphology and the structure of the deposited material were investigated by optical microscopy, scanning electron microscopy and X-ray diffraction. The chemical composition was studied with a scanning electron microscope with an energy dispersive spectrometer, and with an electron probe microanalyser. The topography of the coating was analysed with a stylus profilometer and different thickness profiles were measured depending on the laser-power densities and irradiation times. The morphology of the films showed a strong dependence on the laser-power density, interaction time and partial pressure of TiCl4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01162499
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  • 9
    Electronic Resource
    Electronic Resource
    Laser beam processing of a SiC particulate reinforced 6061 aluminium metal matrix composite (1997)
    Springer
    Journal of materials science 32 (1997), S. 5545-5550 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract SiC particulate reinforced 6061 Al metal matrix composites were laser beam cut using a 3kW continuous wave CO2 laser. The influence of laser processing parameters such as cutting speed, laser power, and shielding gas on the quality of the cuts were investigated. Optical microscopy, scanning electron microscopy and X-ray diffraction were used to analyse the laser treated zone. Experimental results show that 6061 Al metal matrix composites can cut be successfully using laser. A number of Al4C3/Al4SiC4 plates were formed in the heat affected zones due to a chemical reaction between Si and Al that occurred during the laser processing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018668322943
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  • 10
    Electronic Resource
    Electronic Resource
    Structure characterization of a laser-processed Al–Mo alloy (1998)
    Springer
    Journal of materials science 33 (1998), S. 2639-2651 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The surface structure of a laser-processed Al–Mo alloy has been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractory (XRD). The alloy was prepared by first laser alloying a mixture of Al and Mo powders into an Al substrate and then laser remelting the alloyed surface. Following the first laser alloying process, the needle-like equilibrium phases (Al5Mo(h) and Al5Mo(r)) are formed with a broad size ranges and distribute inhomogeneously in the α-Al solid solution matrix. This coarse structure is replaced by a finer, uniform dispersion of dendrites after the subsequent laser remelting. Four basic types of solid states precipitates are observed: (1) irregularly shaped particles constructing the dendrites and having a nearly Al5Mo stoichiometry; (2) needle-like particles which is the Al5Mo (r) phase; (3) Faceted particles having a cubic structure with a stoichiometry close to Al7Mo; (4) tiny, equi-axed particles, with a rather narrow particle size distribution and a cubic structure. © 1998 Chapman & Hall
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004317605718
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