Facultad Regional San Nicolas

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Author: search.filters.author.Benavidez, EdgardoEnd date: 2019

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Now showing 1 - 7 of 7
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    Viscosidad de polvos coladores: comparación entre valores experimentales y modelos teóricos
    (Universidad Nacional de Rosario, 2019-10-01) Santini, Leandro; Martin, Alejandro; Benavidez, Edgardo; Brandaleze, Elena
    En este trabajo se presenta el desarrollo, montaje y puesta en servicio de un equipo para realizar mediciones de viscosidad a altas temperaturas. En particular, se mide la viscosidad de tres polvos coladores comerciales formulados para el colado de aceros ULC identificados como C1, C2 y C3, por el método del cilindro rotativo en el rango de temperatura comprendido entre 1100°C y 1350°C. Los resultados se comparan con modelos teóricos de aplicación industrial, con cálculos termodinámicos empleando el software FactSage 7.2 y con la fluidez evaluada mediante el ensayo del plano inclinado.
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    Correlación entre viscosidad y estructuras vítreas obtenidas a partir de polvos coladores fundidos
    (Universidad Nacional de Rosario, 2019-10-01) Santini, Leandro; Desimone, Mariela; Benavidez, Edgardo; Brandaleze, Elena
    En el presente trabajo se analiza, por medio de difracción de rayos X (DRX) y espectroscopia Raman, la estructura de tres polvos coladores comerciales, obtenidos por enfriamiento rápido (templado) desde la fusión (1300°C). El análisis de la estructura es asociado a valores de viscosidad (método del cilindro rotativo) y fluidez (método del plano inclinado) obtenidos a 1300°C.
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    Thermal analysis techniques applied to study wear mechanisms of black refractories used in the steel continuous casting process
    (Springer, 2019-06-01) Brandaleze, Elena; Benavidez, Edgardo
    In this paper, the results are correlated with information obtained through conventional techniques such as optical microscopy (OM) and scanning electron microscopy (SEM) including EDS analysis and EBSD, that are used to characterize different structural aspects on the refractory material and of the interface with the moud flux adhered on the nozzle. The thermodynamic simulation of the corrosion also contribute with relevant information associated to the main goal of this paper. By the thermochemical simulations, the chemical reactions in the system between nozzle and mold flux are justified. All this information is useful to stablish the coorrosion mechanisms and to predict the dynamic process conditions that cause the damage in the refractory material, in order to improve the nozzle performance.
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    Replacement of fluorine in mould powders: influence on the crystallization kinetics
    (Springer, 2019-06-01) Benavidez, Edgardo; Santini, Leandro; Brandaleze, Elena
    In the present work mould powders were prepared using different raw materials. One powder was fluorine-containing and the others were free-F. The total fluorine content (approx. 10 wt%) was replaced by different percentages of boron, sodium and lithium oxides. Fluorspar (CaF2), borax anhydrous (Na2B4O7), and lithium carbonate (Li2CO3) were employed as source of fluorine, boron, and lithium, respectively. These powders were milling during 2 hours, then were melted at 1300°C and finally fast cooled onto a stainless steel plate. The amorphous solid layers as obtained were milling to produce glass powders which were tested by DTA at different heating rates: 5, 10, and 15°C/min. Several non-isothermal methods (Kissinger, Augis-Bennet, Ozawa, Cheng) were applied to study their kinetics of crystallization. From these models, different parameters associated to crystal growth, such as the activation energy (Ec), the frequency factor () and the nucleation rate (kc), were determined. Crystallographic phases and crystal size distribution were determined by X-ray diffraction and microscopic observation techniques.
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    Analysis of DTA and dilatometric data used to study the behaviour of a mould flux
    (2019-06-01) Benavidez, Edgardo; Santini, Leandro; Brandaleze, Elena
    In the present work a casting powder containing ≈ 36 wt% SiO2, ≈ 31 wt% CaO, 13 wt% Na2O, and 10 wt% CaF2, was used as starting material. A mass of 10 g of the mould powder was placed in a graphite crucible and melted at 1300°C. After 15 minutes at this temperature, the melt was poured onto a stainless steel inclined plate. By this method, solid glass layers were produced, which were sectioned into bars 10-15 mm in length to be used in dilatometric tests. Some of these bars were ground to powder to perform DTA runs. Both tests (DTA and dilatometry) were carried out at different heating rates: 5, 10 and 15 ºC/min, in air atmosphere, up to 900°C. Data of glass transition temperature (Tg), and crystallization peak temperature (Tc) were obtained from DTA and dilatometric runs. From these data, several non-isothermal methods based on Kissinger, Augis-Bennet, Ozawa, and Cheng models, were used to study the crystallization kinetics. Based on these models, the activation energy of crystallization (E), the frequency factor () and the crystallization rate constant (k) were calculated. A subsequent study was followed to determine the Avrami exponent and the crystallized fraction. The crystallographic phases were determined by XRD and the microstructure of samples, treated between 400-900 ºC, was observed by optical and electronic microscopy.
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    Análisis de las impurezas y el tamaño de grano en partículas de magnesia electrofundida sobre el comportamiento de refractarios MgO-C
    (Universidad Nacional de Rosario, 2019-10-01) Lagorio, Yamila; Gass, Sebastián; Benavidez, Edgardo
    El presente trabajo tiene como objetivo estudiar el comportamiento de ladrillos de MgO-C conformados con magnesia electrofundida de distintas calidades. Para esto se conformaron tres ladrillos, identificados como EF1, EF2 y EF3, los cuales fueron formulados con un contenido de MgO del 90% (de calidad electrofundida) y 8,2% de material carbonoso, difiriendo en la pureza, distribución granulométrica y tamaño de grano de las partículas de magnesia.
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    Un estudio de la relación entre granos de magnesia sinterizada/electrofundida en ladrillos de MgO-C
    (Universidad Nacional de Rosario, 2019-10-01) Lagorio, Yamila; Ponte, Ricardo; Vernilli, Fernando; Benavidez, Edgardo
    En este trabajo se estudia la relación entre granos de magnesia, electrofundidos y sinterizados, y su influencia sobre la resistencia a la corrosión, el comportamiento mecánico y la evolución térmica, de ladrillos de MgO-C. El contenido de MgO (90%), material carbonoso (8,2%) y de antioxidantes y ligantes, fueron los mismos en los tres ladrillos conformados, solamente difieren en la calidad y pureza de magnesia utilizada. Las composiciones estudiadas fueron tres: 100% de MgO electrofundida (muestra L1), 40% MgO sinterizada y 60% MgO electrofundida (muestra L2) y 100% MgO sinterizada (muestra L3).