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Poza Rica de Hidalgo, Mexico

Quiroga-Gonzalez E.,University of Kiel | Bensch W.,University of Kiel | Aceves-Mijares M.,National Institute of Astrophysics, Optics and Electronics | Yu Z.,Tianjin Lishen Battery Joint Stock Co. | And 2 more authors.
Thin Solid Films | Year: 2011

The photoluminescence emission of multilayer structures composed of layers of silicon rich oxide with high silicon content and layers of silicon rich oxide with low silicon content obtained by low pressure chemical vapor deposition is here presented. Different parameters for the preparation of the multilayers have been varied such as the Si concentration and the thicknesses of the layers. Additionally, the samples were oxidized at different temperatures. For all samples the photoluminescence seems to have the same origin: defects in the oxide matrix and defects at the interfaces between the Si nanocrystals. The structural and compositional properties of the multilayer structures are discussed. © 2011 Elsevier B.V. All rights reseved. Source


Hernandez-Sanchez E.,National Polytechnic Institute of Mexico | Dominguez-Galicia Y.M.,National Polytechnic Institute of Mexico | Orozco-Alvarez C.,National Polytechnic Institute of Mexico | Carrera-Espinoza R.,Instituto Tecnologico Superior Of Poza Rica | And 2 more authors.
Advances in Materials Science and Engineering | Year: 2014

The effect of the boron potential on the thickness and the mechanical properties of borided layers was evaluated. The boron potential was established by means of the available atoms of boron contained in a control volume inside a cylinder. The cylinders were manufactured from AISI 316L steel, and the boriding treatment was performed using the powder pack technique at a temperature of 1273 K over an exposure time of 6 h. Four different internal diameters of the cylinders were evaluated (3.17, 4.76, 6.35, and 7.93 mm). The mechanical properties were evaluated using the Berkovich instrumented indentation technique. The results showed a clear influence of the boron potential on the mechanical properties of the layers. The hardness of the layers was stablished in the range of 16.22 to 21.16 GPa. Young's modulus values were stablished in the range of 255.96 to 341.37 GPa. Also the fracture toughness and brittleness of the layers reflected the influence of the boron potential supplied during the boriding process. Finally, the influence of the boron potential on the constant of parabolic growth (K) was also established as a function of the inner diameter of the cylinders. © 2014 E. Hernández-Sánchez et al. Source


Hernandez-Sanchez E.,National Polytechnic Institute of Mexico | Chino-Ulloa A.,National Polytechnic Institute of Mexico | Velazquez J.C.,PEMEX | Herrera-Hernandez H.,National Autonomous University of Mexico | And 2 more authors.
Advances in Materials Science and Engineering | Year: 2015

The effect of environmental humidity on the self-lubricating properties of a thin film of boric acid (H3BO3) was evaluated. H3BO4 films were successfully formed on the surface of AISI 316L steel. The study was conducted on AISI 316L steel because of its use in biomedical applications. First, the samples were exposed to boriding to generate a continuous surface layer of iron borides. The samples were then exposed to a short annealing process (SAP) at 1023 K for 5 min and cooled to room temperature while controlling the relative humidity (RH). Five different RH conditions were tested. The purpose of SAP was to promote the formation of a surface film of boric acid from the boron atoms present in the iron boride layers. The presence of the boric acid at the surface of the borided layer was confirmed by Raman spectroscopy and X-ray diffraction (XRD). The self-lubricating capability of the films was demonstrated using the pin-on-disk technique. The influence of RH was reflected by the friction coefficient (FC), as the samples cooled with 20% of RH exhibited FC values of 0.16, whereas the samples cooled at 60% RH showed FC values of 0.02. © 2015 E. Hernández-Sanchez et al. Source


Flores-Rosasa A.,Instituto Tecnologico Superior Of Poza Rica | Kuzinb E.A.,National Institute of Astrophysics, Optics and Electronics | Ibarra-Escamilla B.,National Institute of Astrophysics, Optics and Electronics | Merlo-Ramirez J.M.,Monterrey Institute of Technology
Laser Physics | Year: 2012

We present the investigation of the ON-OFF contrast in an optical switch using stimulated Raman Scattering in optical fibers. The setup consists of a Raman circuit of two fiber stages connected in series with a spectral filter rejecting the signal inserted between them. The stage 1 works as saturated amplifier, in this stage the pump pulses are saturated when pump and signal are launched to the input or travel through the fiber without saturation when pump only is launched at the input. The stage 2 works as a Raman amplifier with amplification depending on the pump power entering from the first stage. When pump only is launched at the input enter to the second stage without saturation and amplifies the signal entering this stage, strong signal pulses appear at the output; when pump and signal are launched to the input the pump is saturated in the first stage and the filter rejected the amplified signal, so that only low power pump enters the second stage and no signal pulses appear at the output. We use 2 ns pump pulses at 1528 nm and continuous-wave signal at 1620 nm. In the first stage of Raman circuit, we use both fibers with normal and anomalous dispersion. In fibers with anomalous dispersion, pump saturation is affected by modulation instability. We find that the contrast may be improved using fibers with normal and anomalous dispersion connected in series in the first stage, provided there is appropriate selection of their lengths. The best achieved contrast was 15 dB at 6 W pump peak power. © Pleiades Publishing, Ltd., 2012. Source

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