In this work the calibration of an Alternative Current Potential Drop (ACPD) system was performed to monitore laboratory mechanical tests on marine environment under cathodic protection. The calibration was done on CT type specimens of API 5L X65 steel dimensioned according to ASTM E1820 standard., The crack propagation during a tensile test with displacement control in an ACPD equipment was monitored through the performs points collection by two channels: one that monitors the crack growth and another that monitors a region free of crack. Using a profile projector and graphical data processing and analysis software, the area of the fracture surface of the specimen was meansured, which allowed to correlate a crack size with a corresponding value of potential drop and the calibration curve. In order to verify verify the efficacy and precision of the technique, step loading tests were performed on API 5L X65 steel test specimens, submerged in synthetic sea water under the overprotection potential of-1300mVAg/AgCl. The results of the calibration showed few dispersed errors, and the main factors of this dispersion may be related to the geometry of the specimen and with variations in current flow density, which is influenced by corners and edges and by the presence of pick-up inductive. The calibration and its effectiveness can be verified through the results of the tests in marine environment, presenting crack lengths close to the actual values, confirming the effectiveness of the ACPD technique.
<p>As propriedades mecânicas de dutos podem ser prejudicadas pela interação hidrogênio-metal devido aos efeitos de substâncias ácidas, tais como o H2S, cuja ação isolada ou combinada com as tensões atuantes na estrutura pode gerar processos de degradação, como a Fragilização por Hidrogênio. Outros fatores podem agravar esse processo, como as tensões residuais. Diante da importância do fenômeno, este trabalho tem como objetivo principal o projeto e desenvolvimento de um sistema de aplicação de esforços em corpos de prova, bem como a realização de testes de permeação eletroquímica de hidrogênio em aço API 5L X60 sob tais condições. Um dispositivo para a realização de testes de permeação eletroquímica de hidrogênio em corpos<br />de prova submetidos a tensões foi projetado e construído. Com isso, foi possível observar, experimentalmente, a influência da tensão sobre o fluxo de hidrogênio permeado sob a amostra durante o experimento. Verificouse que quando o fluxo de permeação de hidrogênio atingiu o estado estacionário de permeação, foi possível alterar esse fluxo com a aplicação de esforços nas amostras. Tensões próximas a 20% do limite de escoamento do material foram suficientes para a observação do fenômeno, já que a permeabilidade foi aumentada em torno de 16% nestas condições.</p>
The Icoaraci district is an important ceramic pole of Pará state (Brazil). The improvement of certain stages ranging from the treatment of the raw material to the ceramic finish is an important point to the production and marketing of the pieces. One of these improvements is the production of a coverage that can be applied to the ceramic surface, characterized by a thin continuous layer of a material called enamel or glaze, which contributes to its aesthetic, mechanical, electrical and sanitary aspects. This study aimed to develop a suitable glaze for use on Icoaraci ceramics, in which bottle glass was used as the main component, varying the amounts of compounds and their firing temperatures. The characterization of the raw materials was performed by X-ray fluorescence, Thermogravimetric and Differential Thermal Analysis. The best result was firing at 900°C, with 5% borax, during 3 hours.
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