Authors: Zafar Turakulov
Comments: 6 Pages. Rejected from the Journal of Mathematical Physics.
Maxwell equations for electromagnetic waves propagating in dispersive media are studied as they are, without commonplace substituting a scalar function for electromagnetic field. A method of variables separation for the original system of equation is proposed. It is shown that in case of planar symmetry variables separate in systems of Cartesian and cylindric coordinates and Maxwell equations reduce to one-dimensional Schr¨odinger equation. Complete solutions are obtained for waves in medium with electric permittivity and magnetic permeability given as ϵ = e^−κz, µ = c^−2e^−λz.
keywords: Maxwell equations, dispersive media, complete solutions
PACS numbers: 41.20.Jb, 42.25 .Bs
Keywords: Maxwell equations, dispersive media, complete solutions
Category: Condensed Matter
Authors: L. F. Zagonel, J. Bettini, R. L. O. Basso, P. Paredez, H. Pinto, C. M. Lepienski, F. Alvarez
Comments: Surface and Coatings Technology Volume 207, 25 August 2012, Pages 72–78 ; http://dx.doi.org/10.1016/j.surfcoat.2012.05.081
A comprehensive study of pulsed nitriding in AISI H13 tool steel at low temperature (400°C) is reported for several durations. X-ray diffraction results reveal that a nitrogen enriched compound (Epsilon-Fe2-3N, iron nitride) builds up on the surface within the first process hour despite the low process temperature. Beneath the surface, X-ray Wavelength Dispersive Spectroscopy (WDS) in a Scanning Electron Microscope (SEM) indicates relatively higher nitrogen concentrations (up to 12 at.%) within the diffusion layer while microscopic nitrides are not formed and existing carbides are not dissolved. Moreover, in the diffusion layer, nitrogen is found to be dispersed in the matrix and forming nanosized precipitates. The small coherent precipitates are observed by High-Resolution Transmission Electron Microscopy (HR-TEM) while the presence of nitrogen is confirmed by electron energy loss spectroscopy (EELS). Hardness tests show that the material hardness increases linearly with the nitrogen concentration, reaching up to 14.5 GPa in the surface while the Young Modulus remains essentially unaffected. Indeed, the original steel microstructure is well preserved even in the nitrogen diffusion layer. Nitrogen profiles show a case depth of about ~43 microns after nine hours of nitriding process. These results indicate that pulsed plasma nitriding is highly efficient even at such low temperatures and that at this process temperature it is possible to form thick and hard nitrided layers with satisfactory mechanical properties. This process can be particularly interesting to enhance the surface hardness of tool steels without exposing the workpiece to high temperatures and altering its bulk microstructure.
Category: Condensed Matter