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  • 1
    Electronic Resource
    Electronic Resource
    Effect of graphitic carbon films on diamond nucleation by microwave-plasma-enhanced chemical-vapor deposition (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2841-2849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond nucleation on very smooth (100) silicon substrates coated with thin films of a colloidal graphite suspension was investigated with a microwave-plasma-enhanced chemical-vapor-deposition system. Nucleation densities of the order of 106 cm−2 were obtained by coating the substrates with carbon films of thicknesses less than 1 μm. However, very low nucleation densities were obtained with carbon film thicknesses greater than 1 μm. The effect of the carbon film thickness on diamond nucleation was examined by measuring the etching rate of carbon films exposed to a hydrogen plasma and was further interpreted on the basis of scanning electron microscopy and Raman spectroscopy results. Etching of the original carbon may lead to the formation of a thin residual carbon film when the initial film thickness is less than a critical value. Results demonstrated that the high nucleation densities of good quality cubo-octahedral diamond crystals obtained with relatively thin carbon films were primarily due to the formation of a porous ultrathin residual carbon film. The critical initial film thickness was a function of the plasma etching and deposition rates of carbon which, in turn, affected the effective local carbon concentration. Thick carbon films yielded insignificant nucleation densities and poor quality diamond because of the high local carbon content resulting from the partial etching of carbon and the increased carbon concentration in the plasma. The local carbon concentration and the residual carbon film are the proposed principal factors for the obtained high diamond nucleation densities on unscratched silicon substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354636
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of substrate temperature on chemical structure of amorphous carbon films (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2243-2248 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous carbon thin films were prepared at 30, 200, and 450 °C by magnetron sputtering of a graphite target. The surface structure and chemical bonding (sp2/sp3) of the carbon films were characterized by scanning tunneling microscopy (STM) and Raman spectroscopy. STM images show that graphite microcrystallites of 20–40 A(ring) in size are present at the surfaces of all the films and the number of the microcrystallites increases with increasing substrate temperature. The microcrystallites often contain structural defects. Raman measurements show that increasing the substrate temperature results in an increase in the sp2-bonded fraction of carbon atoms and a decrease in the microstructural defects. These results indicate that the microstructural changes are correlated with changes in the chemical bonding ratio (sp3/sp3) and no diamond microcrystallites are present in the amorphous carbon. A three-dimensional atomic structure of the graphite microcrystallites is discussed in terms of turbostratic graphite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351122
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of pretreatment process parameters on diamond nucleation on unscratched silicon substrates coated with amorphous carbon films (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 485-492 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond nucleation on unscratched silicon substrates was investigated using a conventional microwave plasma-enhanced chemical vapor deposition system. Silicon substrates were coated with thin films of amorphous carbon using a vacuum arc technique. The carbon-coated silicon substrates were pretreated with a methane-rich plasma at relatively low temperatures and were subsequently exposed to the diamond nucleation conditions. The significance of the pretreatment on the diamond nucleation density was examined by varying the methane concentration, chamber pressure, and exposure time. Scanning electron microscopy demonstrated that densely packed spherical nanoparticles on the pretreated surfaces played the role of diamond nucleation seeds. Raman spectroscopy analysis showed that the nucleation seeds consisted of nonhydrogenated carbon and that their structure was influenced by the pretreatment conditions. Transmission electron microscopy revealed that the nucleation seeds comprised disordered graphitic carbon and ultrafine diamond crystallites. Submicrometer films of good quality diamond possessing significantly higher nucleation densities (∼5×1010 cm−2) were grown from nanoparticles produced under optimum pretreatment conditions. The enhancement of the diamond nucleation density is mainly attributed to the formation of a large number of nanoparticles, which provided sufficient high-surface free-energy sites for diamond nucleation, in conjunction with their high etching resistance to atomic hydrogen stemming from the significant percentage of sp3 atomic carbon configurations, as evidenced by the presence of nanocrystalline diamond in the nanoparticle structure. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360855
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  • 4
    Electronic Resource
    Electronic Resource
    Tribochemical wear of carbon films in oxygen (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4651-4655 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gases sampled directly from the sliding interface of a carbon-coated thin-film magnetic recording disk and a conventional read/write head show that carbon dioxide is generated during sliding in both dry-nitrogen and dry-oxygen environments. The generation rate is approximately ten times greater when sliding in oxygen rather than nitrogen. A novel pressure interface and sampling system was developed for the experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357302
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  • 5
    Electronic Resource
    Electronic Resource
    Drop Formation in a Circular Liquid Jet (1979)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 11 (1979), S. 207-228 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.11.010179.001231
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  • 6
    Electronic Resource
    Electronic Resource
    A generalized compressible Reynolds lubrication equation with bounded contact pressure (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 13 (2001), S. 2237-2244 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new modified Reynolds equation is derived based on physical principles for rarefied gas for compressible and extremely thin layer gas lubrication. For the one-dimensional problem, theoretical analysis and numerical simulation are employed to show that the new equation does not predict an unphysical unbounded pressure singularity in the limit of contact between the bearing surface and the moving surface. We also show the same is true for other existing models with higher than first order slippage correction, which introduce additional diffusion terms that are functions of the spacing with similar order to that of the convection terms. These developments remove the ambiguity of some previously published analyses and correct prior erroneous statements that all existing generalized Reynolds equation models predict nonintegrable singular pressure fields in the limit of contact. The asymptotic analysis also supplies a means for deriving the needed additional boundary condition at the boundary of a contact region. For the two-dimensional problem, we show by numerical analysis that there are also no unbounded contact pressure singularities for the new model and other models with corrections higher than first order, and that the singularity is weaker than in the one-dimensional case for these lower order correction models due to the cross diffusion effect introduced by the additional dimension. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1384867
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  • 7
    Electronic Resource
    Electronic Resource
    Use of an upwind finite volume method to solve the air bearing problem of hard disk drives (2000)
    Springer
    Computational mechanics 26 (2000), S. 592-600 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper we present an upwind higher order finite volume numerical scheme over unstructured triangular mesh to solve the slider air bearing problem of hard disk drives. The scheme is nodal based, which uses the median dual as the control volume. The convection part of the generalized Reynolds equation is modeled by the flux difference splitting technique. Higher order accuracy in space is achieved by a linear reconstruction technique with a flux limiting technique incorporated to prevent oscillation in the high-pressure gradient regions. A linear Galerkin method is used to discretize the diffusion terms. In addition, a non-nested multi-grid iteration technique is used to increase the convergence rate. Finally, the steady state flying attitude of a slider subject to pre-applied suspension force and torques is obtained by a Quasi–Newton iteration method, and the results of this scheme are compared with two other schemes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004660000210
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  • 8
    Electronic Resource
    Electronic Resource
    Plane steady vibration of an orthogonal elastic wedge (1974)
    Springer
    Journal of elasticity 4 (1974), S. 1-16 
    Details
    ISSN: 1573-2681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Das Problem ist durch Superposition zweier Lösungen in der Halbebene auf eine einzige Fredholmsche Integralgleichung Zurückgeführt. Die Formulierung ist exakt im Sinne linearer elasto-dynamischer Theorie. Energieverlust ist durch lineare, viskose Dämpfung an der Oberfläche eingeführt um mathematische Schwierigkeiten zu vermeiden die durch nicht abklingende Oberflächenwellen entstehen wenn keine Dämpfung vorhanden ist.
    Notes: Abstract The problem is reduced to a single Fredholm integral equation by using a superposition of two half-plane solutions. The treatment is exact within the theory of linear elastodynamics. Dissipation is introduced in the form of linear viscous damping at the surface in order to overcome the mathematical difficulties which are associated with the nondecaying surface waves that occur when no dissipation is present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042398
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  • 9
    Electronic Resource
    Electronic Resource
    Plane steady vibration of an elastic wedge (1975)
    Springer
    Journal of elasticity 5 (1975), S. 15-30 
    Details
    ISSN: 1573-2681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Das Problem der ebenen stationären Schwingung eines elastischen Keils mit willkürlichem Winkel (kleiner als 180 Grad) unter harmonischen Normal- und Scherkräften an der Oberfläche wird durch Superposition von zwei Lösungen in der Halbebene auf ein System von singulären Integralgleichungen zurückgeführt. Die Integralgleichungen besitzen Kerne mit Cauchy-Singularitäten vom „non-translation” Typ, ausgenommen für den Keil mit einem Winkel von 90 Grad. Der Ort dieser Singularitäten wird als Funktion des Keilwinkels graphisch dargestellt.
    Notes: Abstract The problem of plane steady vibration of an elastic wedge of arbitrary angle (less than 180 degrees) subject to harmonic normal and shearing tractions on its faces is reduced to a system of singular integral equations by the superposition of two half-plane solutions. The integral equations have kernels with Cauchy singularities of a non-translation type, except for the 90 degree wedge. The locations of these singularity lines are shown graphically as a function of wedge angle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01389255
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