The off-stoichiometry silicon oxide SiO x (x < 2), known as silicon-rich oxide (SRO), and siliconimplanted thermal silicon oxide (SITO) have shown noticeable photoluminescence (PL) at room temperature. Recently, many efforts to increase the PL in these materials have been made. In our experiments, a considerable increase of the visible emission has been observed when the SRO is super-enriched by silicon implantation. In this experiment, SITO and LPCVD-SRO with different silicon excess, Si implanted and no implanted were studied. Different doses of silicon, and annealing in N 2 at different temperature and times were used. PL response was measured before and after annealing. The emission is explained as the decay between traps in the oxide gap. . Also, some effort to correlate the structural properties and the luminescence of these materials has been made [5,6]. Furthermore, the SRO films have been superenriched with silicon implantation [4] and the luminescent properties have been improved. In this work, SITO films were prepared by silicon thermal oxidation and SRO films were prepared by LPCVD. Some samples were implanted with silicon and subsequent annealing was applied during several time intervals. The PL of all of the samples was measured. The emission was studied as a function of silicon excess and annealing time and temperature. Data analysis was done, and a donor-acceptor electron-decay-like mechanism is used to explain the experimental results.
INTRODUCCIÓNEs sabido que la presencia de granos pequeños favorece la resistencia mecánica de los materiales metá-licos, fenómeno que se explica a partir de la clásica ecuación de Hall-Petch. Las potencialidades que resultan de esta relación han derivado en que muchas investigaciones se han dirigido a la tarea de afinar el grano en materiales metálicos, de una forma masiva, a través de técnicas que utilizan deformación plástica severa [1] , por vía electroquímica [2] o mediante transformaciones de fase por deformación [3 y 4] . Otras investigaciones se han abocado a afinar el grano superficialmente, deformando mediante arenado [5][6][7][8] , bombardeo con esferas [9 y 10] , pulsos de ultrasonido [11] , atrición [12] y más recientemente, mediante el uso de A. Gallegos*, C. Camurri*, C. Carrasco* y F. Soldera**
ResumenEn este trabajo se realizaron ensayos de aplicación de plasma electrolítico (PE) sobre alambres delgados de acero inoxidable AISI 302 en una solución inerte. Las probetas se sometieron a ensayos de tracción, con el fin de medir cambios en su resistencia mecánica; adicionalmente fueron evaluadas en sus cambios morfológicos y microestructurales. Se encontró que después de 10 s de aplicación de PE, la superficie de las probetas estaba uniformemente cubierta por nódulos y cráteres propios del ciclo de fusión y enfriamiento del PE; se evidenció un significativo afinamiento del grano superficial, llegando a ordenamientos cristalinos de tamaño menor a 200 nm y también se observó que la capa superficial afectada presentó un incremento de la resistencia a la tracción de al menos un 57 % respecto al acero base.
Palabras clavePlasma electrolítico; Electrólisis de alto voltaje; Nanoestructuración superficial; Nanogranos; Resistencia a la ruptura; Oxidación por plasma electrolítico.
Effects of surface modification of thin wires of AISI 302 stainless steel by electrolytic plasma on its mechanical properties AbstractIn this work different tests using electrolytic plasma (EP) on thin wires of stainless steel AISI 302 in an inert solution were performed. Tensile tests were carried out in order to measure changes in the mechanical strength of the samples; moreover, both the morphological and microstructural changes also were evaluated. It was found that after 10 s of the application of EP, the samples surface was uniformly covered by nodules-like and craters similar to those found in the melting and cooling periods of EP. The results show a significant surface grain refinement, leading to crystalline arrangements with sizes less than 200 nm and also an increase in the samples tensile strength of at least 57 % respect to steel base.
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