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Search Results: 1 - 10 of 356626 matches for " Oladis Troconis de Rincón "
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Six-Year Evaluation of Thermal-Sprayed Coating of Zn/Al in Tropical Marine Environments
Orlando Salas,Oladis Troconis de Rincón,Daniela Rojas,Adriana Tosaya,Nathalie Romero,Miguel Sánchez,William Campos
International Journal of Corrosion , 2012, DOI: 10.1155/2012/318279
Abstract: The main objective of this research was to evaluate the performance of thermal-sprayed coating of Zn/Al (double layer) after six years of exposure, with and without the use of sealant (wash primer) in tropical marine environments of very high aggressiveness: La Voz Station (located at the Peninsula de Paraguaná/Falcón State) and Lake Maracaibo Crossing Station (located at Zulia State), in Venezuela. To that effect, carbon steel coupons (100?mm × 150?mm × 2?mm) were sprayed by flame process. The coupons were characterized by means of initial weight, thickness, metallographic, adherence, and roughness, being evaluated monthly by visual inspection during six years. After removal, the coupons were evaluated by microscopic analysis to determine the morphology of attack, microstructure, penetration of contaminants, composition, and morphology of corrosion products. The results showed that after six years, the double-layer system represents an excellent choice for corrosion protection of steel by combining the galvanic protection of zinc with the erosion resistance of aluminum. However, due to the erosion-corrosion effect, a sealant such as wash primer can be used in order to extend its service life. 1. Introduction Worldwide, many organizations have made numerous efforts in terms of studies and research looking for new coating systems to improve the durability of structures exposed to marine and coastal marine environments, providing protection to the steel during its service life and producing a minimal impact on the environment. In marine and coastal marine environments, where a number of factors are present such as high-chloride concentrations, strong winds, changing conditions of relative humidity and temperature (especially in tropical climates like Venezuela), organic coatings do not perform properly. In this regard, thermal-sprayed coatings appear as an alternative to protect steel structures in those environments. In the United States, Europe, and Japan [1, 2], these coatings are gaining importance for their promising low environmental impact, corrosion resistance, cost benefits, durability, and other advantages over other conventional paint systems. In 1974, the American Welding Society [3] performed a study that was considered a pioneer in thermal sprayed coating where it reported that these coatings with Zn and Al, with and without sealer, exposed in marine and industrial environments, provided protection against corrosion for 19 years. Moreover, in 1987, the Laque Center for Corrosion Technology, INC. [4] reported that the degree of protection of
Estudio comparativo del efecto del ambiente entre ánodos localizados de Zn y Al/Zn/In en concreto armado Ambient effect comparative performance between Zn and Al/Zn/In point anodes in reinforced concrete
Yolanda Hernández López,Oladis Troconis de Rincón,Andrés Torres Acosta,Angélica del Valle Moreno
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: Esta investigación presenta el estudio de ánodos localizados de cinc evaluados en laboratorio después de un período de tres a os. Se fabricaron para su evaluación doce vigas de concreto reforzado, seis de 60 × 10 × 15 cm y seis de 120 × 20 × 30 cm. Las mezclas de concreto fueron preparadas con y sin contaminación de cloruros. La contaminación se realizó adicionando al agua de la mezcla entre 1%p/p y 3,5%p/p de cloruros en base al peso de cemento. Las vigas fueron expuestas a dos humedades relativas diferentes, una constante de ≈ 95% y la externa del laboratorio de ≈ 77 %. Los ánodos localizados de cinc disponibles comercialmente, se colocaron en uno de los extremos de la viga para determinar la polarización alcanzada por la barra al conectar el ánodo y la barra de acero. Se midieron los potenciales de media celda, la velocidad de corrosión, la distribución de corriente y despolarización del acero. Así mismo, los ánodos de aluminio/cinc/indio fueron evaluados a humedad relativa de ≈ 77%en vigas similares de 120 × 20 × 30 cm. En este trabajo se muestra que la eficiencia del ánodo para lograr polarizar a la barra de refuerzo depende de la humedad ambiental y por lo tanto de la resistividad del concreto; determinándose que los ánodos de sacrificio sólo alcanzarían proteger zonas de alta humedad relativa, como es el caso de estructuras expuestas en zonas de oleaje y salpique. This investigation presents the performance of zinc-based point anodes based on laboratory results after a three years evaluation period. Twelve small reinforced concrete beams, six 60 × 10 × 15 cmand six 120 × 20 × 30 cm, were fabricated for this evaluation. Concrete mixtures were prepared with and without chloride contamination. Chloride contamination was achieved adding between 1% and 3.5 wt% chlorides by cement weight during mixing. Beams were exposed to two different relative humidities, either constant ≈ 95% RH or outdoor ≈ 77 % RH. The commercially available zinc-based point anodes were placed at one end of the beams to determine how polarized the rebars get when interconnection between the anode and the steel was achieved. Half cell potentials, current distribution, and polarization decay due to the anode interconnection with the rebar were measured. On the other hand, aluminium/zinc/indium anodes were evaluated at ≈ 77 % RH by using similar beams. This investigation presents the anode polarization efficiency, which depends of the environment humidity and, in turns, to the concrete resistivity. It was determined that these anodes might protect steel in highly humid concrete, lik
Ambient effect comparative performance between Zn and Al/Zn/In point anodes in reinforced concrete
Hernández López,Yolanda; Troconis de Rincón,Oladis; Torres Acosta,Andrés; Moreno,Angélica del Valle; Rodríguez Montero,José; Berríos,Freddy; Montero,Pablo;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: this investigation presents the performance of zinc-based point anodes based on laboratory results after a three years evaluation period. twelve small reinforced concrete beams, six 60 × 10 × 15 cmand six 120 × 20 × 30 cm, were fabricated for this evaluation. concrete mixtures were prepared with and without chloride contamination. chloride contamination was achieved adding between 1% and 3.5 wt% chlorides by cement weight during mixing. beams were exposed to two different relative humidities, either constant ≈ 95% rh or outdoor ≈ 77 % rh. the commercially available zinc-based point anodes were placed at one end of the beams to determine how polarized the rebars get when interconnection between the anode and the steel was achieved. half cell potentials, current distribution, and polarization decay due to the anode interconnection with the rebar were measured. on the other hand, aluminium/zinc/indium anodes were evaluated at ≈ 77 % rh by using similar beams. this investigation presents the anode polarization efficiency, which depends of the environment humidity and, in turns, to the concrete resistivity. it was determined that these anodes might protect steel in highly humid concrete, like parts of the structures exposed to splash and/or tidal zone.
Evaluación de sistemas de recubrimientos duplex en ambientes marinos tropicales Evaluation of duplex coating’s system in tropical marine environments
Nathalie Romero,Oladis de Rincón,Miguel Sánchez,álvaro Rincón
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: En este trabajo se seleccionaron nueve esquemas de diferentes empresas del mercado nacional, de reconocida trayectoria, para realizar la evaluación en ambientes muy severos, marinos tropicales. A tal efecto se utilizaron perfiles de acero galvanizado nuevo y ya expuesto (con corrosión del sustrato), a las mismas condiciones de evaluación. Se seleccionaron dos estaciones de campo: La Voz y El Cruce del Lago de Maracaibo, ambos climas marinos tropicales de elevada agresividad. Adicionalmente, se efectuaron ensayos acelerados en una estación en el Centro de Estudios de Corrosión (CEC), utilizando la norma ISO 11474, y en el laboratorio (Cámara climática/PROHESION). Cabe destacar que luego de mas de 36 meses de exposición en las estaciones de campo, el desempe o de los diferentes esquemas sobre galvanizado ya expuesto se observa claramente definido, pudiendo seleccionar fácilmente el que muestra un mejor comportamiento. No obstante, para el caso del galvanizado nuevo, luego de este tiempo de evaluación, no se aprecia tan evidente la diferencia en el comportamiento; ya que esquemas de recubrimiento con un pobre desempe o en el galvanizado expuesto presentan un buen comportamiento en ese sustrato, demostrando la eficiencia de los sistemas Duplex. In this work nine different coating systems, from national suppliers, were selected to perform the evaluation in two severe tropical marine environments. New galvanized profiles as well as pre-exposed to the same environmental conditions were used as the test probes. Two different field stations were selected: La Voz and The Cross of Maracaibo Lake. Additionally, accelerated test were carried out in a station located at Centro de Estudios de Corrosión (CEC) by using the standard ISO 11474, and in the laboratory (PROHESION chamber). It is important to emphasize that after more than 36 month-exposure the behavior of the different coating systems on pre-exposed galvanized was clear, permitting to select the coating system with the best performance. Nevertheless in the case of new galvanized probes, after the evaluation period, most of the duplex systems had a very good performance.
Costos por corrosión en el mantenimiento preventivo y correctivo de equipos e instalaciones en la industria Corrosion costs in preventive and corrective maintenance in equipment and facilities in industry
Bertila Aponte,Matilde Fernández de Romero,Oladis oconis de Rincón,Silagdy Arias
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2008,
Abstract: El propósito de esta investigación fue determinar los costos por corrosión en función del tipo de corrosión y el control aplicado, asociados al mantenimiento correctivo y preventivo en una industria eléctrica y de alimentos en Venezuela, mediante la aplicación del “Software” SACIC dise ado para ello. Inicialmente, se hizo la clasificación de las órdenes de trabajo asociadas a las labores de mantenimiento para determinar las relacionadas con corrosión, durante un a o de operación de las plantas. Se seleccionaron 224 órdenes de trabajo en la industria eléctrica y 335 en la de alimentos. Según el tipo de corrosión la planta eléctrica tuvo un costo de 366.229.194,58 bolívares; de este total, los costos ocasionados por la corrosión uniforme y corrosión erosión fueron los más relevantes, mientras que para la planta de alimentos los costos fueron de 521.612.453 bolívares, generados en su mayor parte por corrosión uniforme. En lo que respecta a los costos generados por control de corrosión, los mismos fueron de 527.105.626,76 bolívares para la planta eléctrica y de 742.766.105 bolívares para la planta de alimentos, representando el 10% y 5% del costo anual por mantenimiento respectivamente. Con este trabajo se logró, además de la segregación de los costos por corrosión y su impacto en los costos por mantenimiento, estandarizar un procedimiento para la determinación del costo en función del tipo y control de corrosión, aplicable a cualquier industria. The purpose of this research was to determine corrosion costs according to the corrosion types and the controls applied associated to corrective and preventive maintenance in an electricity plant and a processing food in Venezuela, through the Software SACIC designed for this application. Initially, it was done the classification of work orders associated with maintenance work to determine those related to corrosion, for one year of operation of the plant. There were chosen 224 working orders which corresponded to the electrical plant industry and 335 to the food industry. According to the type of corrosion, the electricity plant had a cost of 366,229,194.58 Bolivares, being the costs related to uniform and erosion corrosion the most relevant, while for the food processing plant the costs were 521,612,453 Bolivares, generated by uniform corrosion. In relation to the costs generated by corrosion control, they were 527.105.626,76 Bolivares in the electricity plant and 742.766.105 Bolivares in the food processing plant, which represented 10% and 5% of the annual maintaining cost, respectively. This research permitted
Efecto de los iones ferrosos, el pH y el H2S a nivel de interfase en el mecanismo de corrosión del hierro por bacterias sulfato-reductoras Influence of ferrous ions, pH and H2S at the interface on the corrosion mechanism of iron by Sulfate-Reducing Bacteria
Lisseth Ocando,Matilde Fernández de Romero,Orlando Pérez,Oladis T de Rincón
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: La Corrosión Inducida Microbiológicamente (MIC) por Bacterias Sulfato-Reductoras (BSR) es un fenómeno que acarrea graves da os para muchas industrias y sistemas. Numerosas teorías se han formulado para explicar los mecanismos que gobiernan MIC y, recientemente, ha sido propuesto un mecanismo de corrosión del hierro por estas bacterias. En este mecanismo se ha establecido que los sulfuros de hierro precipitados son los que propician el proceso corrosivo del acero, junto con el H2S generado por las BSR, y supone que, por la actividad metabólica de las mismas, en la interfase metal/solución ocurre un descenso del pH que acelera el proceso corrosivo de forma localizada. Por tanto, el objetivo principal de esta investigación consistió en evaluar el pH a nivel de interfase metal/solución, tanto en medios con iones ferrosos (al igual que en el mecanismo) como en ausencia de ellos, con el propósito de verificar la ocurrencia de esta acidificación y determinar la influencia de estos iones en el proceso corrosivo. También, evaluar la concentración deH2S a nivel de interfase y determinar su relación con el pH. Para medir estos dos parámetros durante 24 horas en ambos medios, se utilizó microelectrodos de pH y H2S. Por otro lado, se determinó la morfología de biopelícula y de ataque en los dos medios de cultivo mediante microscopía electrónica de barrido (MEB). Los resultados arrojaron que el pH disminuye a nivel de interfase metal/solución dependiendo de la presencia de iones ferrosos. Adicionalmente, con esta investigación se confirmó la influencia adversa de los iones Fe++ y la agresividad de los sulfuros de hierro en el proceso corrosivo. Microbiologically Influenced Corrosion (MIC) by Sulfate-Reducing Bacteria (SRB) has been the subject of extensive studies for the past five decades and several theories have been proposed to explain the mechanisms governing MIC. Recently, a corrosion mechanism for the action of SRB on iron was proposed, which seeks to explain the initiation of this kind of corrosion in order to improve prevention and mitigation techniques. This mechanism was supported on the fact that there should be a local pH decrease at the metal/solution interface. So, the principal aim of this work was to prove this theory by evaluating an iron interface exposed to a culture medium rich in nutrients and SRB. The H2S concentration produced was also evaluated to establish its relation with the pH at the interface. To measure these parameters during 24 hours, pH and H2S microelectrodes with tip diameters of 10 μm were used. A SRB pure culture of Desulfovibri
Development of a model to predict the durability of reinforced concrete structures in marine environment
Morón,Oleyda; de Rincón,Oladis; García,Cézar; Arrieta,Idelfonso; Bravo,José;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2003,
Abstract: this paper proposes a model that enable to estimate the durability of reinforced concrete structures exposed to marine environment. to that effect, different models proposed by the literature were used, where the diffusion coefficient is function of the concentration, departing of the fact that the transfer process of the chloride ions is controlled by purely diffusion flow. a total of 44 concrete nucleus served as base for this research. thus, the results of chloride ions contamination determined in different elements of the general rafael urdaneta bridge (pgru) were used. the pgru, a 39 year structure, is located front caribbean sea with a very aggresive environmental condition. the results indicate that it does not exist an unique model that is applied to all the evaluated structure, for the valuation criteria assumed in the selection of the models, but, as a rule depend on the quality of the concrete (equal model for a same element). however, the hall′s model was the one which fit better to the results (70% of the cases).
Operational factors affecting the hot dip galvanizing steel
Sánchez,Miguel; Contreras,Ramón; Pérez,Orlando; de Rincón,Oladis; Campos,William;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: an evaluation by hot dip galvanizing on steel after a 1; 2 and 3-minutes immersion was studied. these samples were carried out for evaluating microhardness and thickness measurements. electrochemical techniques were used to determined the corrosion rate of steel in acid pickling 5; 10 and 16% hcl; rinsed with water of ph 2.50; 3.50 and 4.50 and hot dip galvanized steel in 3.5% nacl. certain operational parameters were analyzed, such as the aging bath (hcl), and elimination of the rinsing stage, to observe their influence in the hot dip galvanizing coating. it was found that an increase of coating thickness of hot dip galvanizing steel decreased the corrosion rate and the microhardness. surfaces of alloy layer of the coating were examined by scanning electron microscope (sem). sem measurements was determined that when obvious the rinsing, the chlorine can be catched between two layers (interface), and soon migrates of the outermost alloy layer of the coating (delta) towards the innermost one (gamma).
Factores operacionales que afectan el comportamiento del acero galvanizado por inmersión en caliente Operational factors affecting the hot dip galvanizing steel
Miguel Sánchez,Ramón Contreras,Orlando Pérez,Oladis de Rincón
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2007,
Abstract: En este trabajo se presentan los resultados de la evaluación de probetas de acero galvanizado por inmersión en caliente con tiempo de ba o de 1, 2 y 3 minutos. Se realizaron ensayos de espesor de recubrimiento y mediante técnicas electroquímicas se midió la velocidad de corrosión del acero en soluciones de ba os ácidos a 5; 10 y 16% de HCl y agua de enjuage pH 2,50; 3,50 y 4,50; y del acero galvanizado en una solución de NaCl 3,5%. Se analizaron ciertos parámetros operacionales, tales como el envejecimiento del ba o ácido (HCl), y eliminación de la etapa de enjuague, para observar su influencia en el recubrimiento de cinc. Se encontró que a medida que aumenta el espesor del recubrimiento disminuye la velocidad de corrosión. Mediante el uso del microscopio electrónico de barrido se determinó que cuando se obvia el enjuague, el cloro puede quedar atrapado entre dos capas (interfase), y luego migra de la capa superior (Delta) hacia la inferior (Gamma). An evaluation by hot dip galvanizing on steel after a 1; 2 and 3-minutes immersion was studied. These samples were carried out for evaluating microhardness and thickness measurements. Electrochemical techniques were used to determined the corrosion rate of steel in acid pickling 5; 10 and 16% HCl; rinsed with water of pH 2.50; 3.50 and 4.50 and hot dip galvanized steel in 3.5% NaCl. Certain operational parameters were analyzed, such as the aging bath (HCl), and elimination of the rinsing stage, to observe their influence in the hot dip galvanizing coating. It was found that an increase of coating thickness of hot dip galvanizing steel decreased the corrosion rate and the microhardness. Surfaces of alloy layer of the coating were examined by scanning electron microscope (SEM). SEM measurements was determined that when obvious the rinsing, the chlorine can be catched between two layers (interface), and soon migrates of the outermost alloy layer of the coating (Delta) towards the innermost one (Gamma).
Desarrollo de un modelo para predecir la durabilidad de estructuras de concreto armado en medios marinos Development of a model to predict the durability of reinforced concrete structures in marine environment
Oleyda Morón,Oladis de Rincón,Cézar García,Idelfonso Arrieta
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2003,
Abstract: Este trabajo tiene como finalidad proponer un modelo que permita estimar la durabilidad de estructuras de concreto armado expuestas a un ambiente marino. A tal efecto, se utilizaron diferentes modelos propuestos por la literatura, donde el coeficiente de difusión es función de la concentración, partiendo de que el proceso de transferencia de los iones cloruro es controlado por un flujo puramente difusional. Un total de 44 núcleos de concreto sirvieron como base para esta investigación. Así, se utilizaron los resultados de contaminación de iones cloruro determinados en diferentes elementos del Puente General Rafael Urdaneta (PGRU), estructura de concreto de 39 a os en servicio. El PGRU se encuentra frente al Mar Caribe con condiciones ambientales marinas agresivas. Los resultados indican que no existe un modelo único que se aplique a toda la estructura evaluada, para los criterios de valoración asumidos en la selección de los modelos, sino que, en general dependen de la calidad del concreto (igual modelo para un mismo elemento). Sin embargo, fue el modelo de Hall el que mostró el mejor ajuste a los resultados (70% de los casos). Además se observó que la calidad del concreto tiene un marcado efecto sobre la difusión del ión cloruro y que en general el coeficiente de difusión se ve más afectado por agentes externos que por la variación de la concentración dentro del concreto. This paper proposes a model that enable to estimate the durability of reinforced concrete structures exposed to marine environment. To that effect, different models proposed by the literature were used, where the diffusion coefficient is function of the concentration, departing of the fact that the transfer process of the chloride ions is controlled by purely diffusion flow. A total of 44 concrete nucleus served as base for this research. Thus, the results of chloride ions contamination determined in different elements of the General Rafael Urdaneta Bridge (PGRU) were used. The PGRU, a 39 year structure, is located front Caribbean Sea with a very aggresive environmental condition. The results indicate that it does not exist an unique model that is applied to all the evaluated structure, for the valuation criteria assumed in the selection of the models, but, as a rule depend on the quality of the concrete (equal model for a same element). However, the Hall′s model was the one which fit better to the results (70% of the cases).
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