Examinando por Autor "Gómez-Botero, M. A. (Maryory Astrid)"

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    Comportamiento mecánico y de fraguado de morteros de cemento Pórtland gris tipo III con aditivos
    (2013-11-27) Montoya-Toro, Y. A. (Yirson Alberto); Cadavid, A. (Albeiro); Gómez-Botero, M. A. (Maryory Astrid)
    In the present work the variability in the performance of mortars by using different batches of two types of additives, one retardant and one accelerant of setting was studied, for this purpose, their behavior was compared with a mortar without additive. The physical, mechanical, and chemical properties of the gray Portland cement type III from Cementos Rioclaro, the initial and final setting times using different doses of additive were measured; besides, compression strength tests of mortars with retardant additive were made. Between the additives batches studied a small variability was found; the retardant additive used with a content of 0,6 wt % of cement showed that as the higher initial setting time, final setting time is higher. Using the additive in doses up 0,6 % wt of cement and increase of the retard time around 550 y 600 min with the increase in the additive content. Similarly, with the increase of the retardant additive diminishes the initial strength and increases the final strength of the mortar. With growing doses of accelerant content additive diminished the setting time of the mixes studied.
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    Efecto de la temperatura sobre la resistencia a la tracción de algunos refuerzos de fibras para matrices cerámicas o poliméricas
    (2013-11-27) Gómez-Botero, M. A. (Maryory Astrid); Alzate, C. C. (Claudia Cecilia); Márquez, A. (Alexánder); Restrepo, José William; Jaramillo-Isaza, F. (Franklin)
    This paper presents a study of the thermomechanical properties of low carbon steel, AISI-SAE 304 stainless steel, aramid and carbon fibers. Moreover, surface aspect of mineral rock wool of and aluminosilicate wool reinforcements was analyzed prior and after submitting to heat treatments at 1000 ºC. The tensile resistance of the fibers was evaluated prior and after submitting to heat treatments at temperatures of 400, 600, 800 and 1000ºC depending on the degradation that they showed. Moreover, a thermogravimetric analysis was carried out on each kind of fiber to determine the changes in weight at different temperatures. The stainless steel fibers showed the highest mechanical stability, whereas the aramid fibers with treatments at 400ºC showed practically null mechanical properties.
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    Efecto del contenido de carbono sobre la resistencia al desgaste abrasivo de recubrimientos de CrC depositados por pulverización catódica magnetrón
    (2013-11-05) Gómez-Botero, M. A. (Maryory Astrid); Lousa, A. (Arturo); Esteve, J. (Joan)
    Chromium carbide coatings on steel are a good candidate for applications on forming and molding dies. The high mechanical strength, chemical resistance and high temperature stability of Cr3C2 phase can be compatible with the severe abrasive wear and corrosion found in those manufacture operations. In this work chromium carbide coatings deposited by means of RF magnetron sputtering showed carbon contents between 25 % and 58 % by EDS analysis. Hardness values of these coatings were between 15 and 24 GPa, being the hardest values in the samples with carbon content in the 39-53 % range. The abrasive wear behavior of the coatings was evaluated by using a dimple grinder with diamond powder. The volume of the abrasion craters was measured from the images obtained with the interferometric microscope, and further corroborated by geometrical volume calculation based in profilometer sections that were measured. Abrasive wear behavior showed a marked dependence with carbon content. The lowest abrasive wear was obtained for the coatings with the highest carbon content.
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    Influencia de los recubrimientos dúplex sobre las propiedades mecánicas y resistencia al desgaste del acero AISI 4140 bonificado
    (2013-10-28) Bolívar-Osorio, F. J. (Francisco Javier); Bejarano-Gaitán, G. (Gilberto); Gómez-Botero, M. A. (Maryory Astrid)
    The AISI 4140 steel is a low chrome/molybdenum alloyed steel with high tensile strength and good toughness, which is normally used for the manufacture of machine parts such as gears, crank shafts, camshafts, etc. However, its wear resistance is quite limited and this is usually improved by nitriding surface treatment. The purpose of this study was to increase the mechanical properties and wear resistance of 4140 steel by applying a DUPLEX surface treatment consisting of a liquid nitriding (known as Teniffer) followed by the deposition of a titanium nitride (TiN) hard coating. The crystalline microstructure was evaluated by Xray diffraction (XRD), morphology and elemental chemical composition was determined by microscopy SEM and energy dispersive X-ray spectroscopy (EDS), tribological properties were tested using a tribometer type ballondisc and micro hardness was determined by the Vickers method.
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    Marcado con láser sobre cerámica vidriada por aporte superficial de un pigmento de cobalto
    (2014-05-12) Gómez-Botero, M. A. (Maryory Astrid); Restrepo-Montoya, J. W. (José William)
    Laser materials processing has great application to industrial scale, to print graphic patterns on ceramics surfaces. The fast implementation of this process is due to the fact that, with respect to the conventional baking process, has advantages, such as: heat is concentrated only in the radiated zone that involves a smaller energy consumption without affecting significantly the rest of the piece, graphic patterns with of highly spatial resolution are obtained, it permits to introduce changes during the process without requiring long stops, and low or almost none generation of residues. In this study the results obtained from Nd:YAG (λ=1064 nm) laser glazing on the enameled surfaces of glazed tiles, which were previously covered with black of cobalt pigment, are presented. With the laser operating in continuous wave (CW), a series of lines were marked, whose width and depth showed a direct dependence with the variation in the power and scan speed of the laser beam on the surface of the glazed tile. Finally, these glazed lines were characterized by optical microscopy, energy dispersion spectroscopy (EDS), and X-ray diffraction (XRD).
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    Propiedades mecánicas y comportamiento tribológico de recubrimientos multicapa de CRN/TIN
    (2013-11-15) Gómez-Botero, M. A. (Maryory Astrid); Bejarano-Gaitán, G. (Gilberto); Cano, D. A. (Diego Alejandro); Osorio, Jaime Alberto; Bolívar-Osorio, F. J. (Francisco Javier)
    Multilayer coatings represent a promising class of protective coatings due to the improvement in tribological, mechanical, and anticorrosive properties conferred to the coated surfaces. This has motivated the research, development and implementation of these materials in many industrial applications; nowadays the requirements of the industry are not satisfied with materials that have a good property, but a combination of good properties for most of the applications. In this work CrN/TiN multilayer coatings were deposited by magnetron sputtering; the variation of number of coating bilayers with 4 μm total thickness was of 10, 40, 80 and 100. The grain size and the roughness of coatings were determined by means of atomic force microscopy; micro hardness and scratch adhesion tests were performed, the friction coefficients were evaluated in a ball on disk tribometer, and the abrasive wear resistance was determined by Calotest method. for the sample with 10 bilayers to 29.8 GPa for the sample with CrN / TiN 100 bilayers..
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    Vidriado con láser de Nd:YAG sobre azulejos recubiertos de barnices de cobalto con frita borácica y sin frita
    (2013-11-26) Gómez-Botero, M. A. (Maryory Astrid); Restrepo, José William
    Ceramic and architectonic materials industries employ different marking techniques with two classical applications, identification and decoration of manufactured objects. Laser techniques using for these proposes are been implemented in growing way, due to theirs advantages with regard to the conventional baking such as: heat is concentrated only on the radiated zone which involves a smaller energy consumption without affecting significantly the rest of the piece; graphic patterns with of highly spatial resolution are obtained; it permits to introduce changes during the process no requiring long stops and low or almost none generation of residues. In this study the results obtained from Nd:YAG (l=1064 nm) laser glazing on the enameled surfaces of glazed tiles, which were previously covered with cobalt black pigment and an enamel constituted with this same pigment and borax frit, are presented. With the laser operating in continuous wave (CW), a series of lines were marked, whose width and depth showed a direct dependence with the variation in the power and scan speed of the laser beam on the glazed tile surface. Finally, these glazed lines were characterized by optical microscopy, energy dispersión spectroscopy (EDS), and X- ray diffraction (XRD).