4 resultados para foil

em Universidade Federal do Rio Grande do Norte(UFRN)


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The present paper analyses matters about the assessment in the context of the school organization in cycles. The complexity that involves the assessment turns it into a difficult subject, since the evidence that the model supported by the traditional approach contributes to foil the fulfillment of new continuous and wide-ranging assessment practices, that are coherent with a view of learning as a process established in the student-teacher-knowledge interaction. This paper has as guidance the following questions: How did the introduction of the teaching organization in cycles happen in Fortaleza/ CE? How far are the teachers prepared to the introduction of the cycles system, specially in the way of thinking and practicing the assessment? What are the teacher s involvements with this project and with the continuous assessment in the cycles? What meanings do the teachers give to the assessment in this project? Therefore, were determined as objectives: to comprehend the meanings attributed to the learning assessment by the teachers in contact with the cycles in Fortaleza/CE; to identify assessment practices that are closer to a less qualifying perspective, more related to the students learning and to the educational intervention in order to improve this process. The methodological orientation chosen was based on the presuppositions of the comprehensible interview, with reference to the studies of the French sociologist Jean Claude Kaufmann, developed with 15 (fifteen) teachers of 15 (fifteen) schools of the state teaching system of Fortaleza/CE. It was considered, in the methodology, the word as a central fact in the consolidation of the object of study, what allows to conceive the teachers as active participants of this research and of the discussions about assessment. The analysis about the speeches in the interviews made possible to glimpse the meanings attributed to the learning assessment that are not related to the traditional paragon, in spite of the dilemma in which the participants of the research faced at the time of the introduction of the cycles in Fortaleza/CE. These meanings were created between the presence and the absence of the teachers knowledge that, in their way, interact with the changes caused by the obligation of the teaching organization in cycles, seeking a strategy of self-organization as a consequence of the search for new knowledge connected with the teaching

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This research work is based, in search of reinforcement s vegetable alternative to polymer composites. The idealization of making a hybrid composite reinforced with vegetable fibers licuri with synthetic fibers is a pioneer in this area. Thus was conceived a hybrid composite laminate consisting of 05 (five) layers being 03 (three) webs of synthetic fibers of glass and E-02 (two) unidirectional fabrics of vegetable fibers licuri. In the configuration of the laminate layers have alternating distribution. The composite laminate was manufactured in Tecniplas Commerce & Industry LTD, in the form of a card through the manufacturing process of hand lay up. Licuri fibers used in making the foil were the City of Mare Island in the state of Bahia. After cooking and the idealization of the hybrid composite laminate, the objective of this research work has focused on evaluating the performance of the mechanical properties (ultimate strength, stiffness and elongation at break) through uniaxial tensile tests and three point bending. Comparative studies of the mechanical properties and as well as among other types of laminated hybrid composites studied previously, were performed. Promising results were found with respect to the mechanical properties of strength and stiffness to the hybridization process idealized here. To complement the entire study were analyzed in terms of macroscopic and microscopic characteristics of the fracture for all tests.

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This paper suggests modifications in coating of electrodes providing an alternative for execution of welding with low hydrogen electrode AWS E7018 without having to dry it, reducing thus the cost and time of manufacturing of high resistance welds. The welds in this research were developed with basic coated electrodes (hygroscopic) – SMAW process – externally painted with aluminum spray paint for high temperatures or wrapped with thin plastic films (PVC) and aluminum foil films used commonly for food protection. The basic premise is that establishing a barrier between the atmosphere and the electrode coating could reduce the effects of high hygroscopicity presented by coatings of low hydrogen, minimizing this way the main source of supply of hydrogen to the fusion pool during welding. It is also expected that the addition of new materials from the electrode coating to the fusion pool would induce metallurgical changes in the deposited metal and, as a consequence, modifications in its mechanical properties. This research dealt with measuring the dissolved hydrogen in the deposited metal after welding with modified electrodes, evaluating the influence of these changes in the produced microstructures and in the mechanical properties of the resulting weld, and comparing the obtained results with the standard welding procedures and with the recently developed waterproof electrodes. The results obtained in most samples welded with modified electrodes showed increased mechanical resistance and increased tenacity due to the increased percentage of acicular ferrite in metal deposited without significant elevation of hardness, when compared with the traditional welding with AWS E7018 electrode and with ELBRÁS BRH4R waterproof electrode. The diffusing hydrogen measured in the modified electrodes was kept inside the parameters defined by international codes.

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This paper suggests modifications in coating of electrodes providing an alternative for execution of welding with low hydrogen electrode AWS E7018 without having to dry it, reducing thus the cost and time of manufacturing of high resistance welds. The welds in this research were developed with basic coated electrodes (hygroscopic) – SMAW process – externally painted with aluminum spray paint for high temperatures or wrapped with thin plastic films (PVC) and aluminum foil films used commonly for food protection. The basic premise is that establishing a barrier between the atmosphere and the electrode coating could reduce the effects of high hygroscopicity presented by coatings of low hydrogen, minimizing this way the main source of supply of hydrogen to the fusion pool during welding. It is also expected that the addition of new materials from the electrode coating to the fusion pool would induce metallurgical changes in the deposited metal and, as a consequence, modifications in its mechanical properties. This research dealt with measuring the dissolved hydrogen in the deposited metal after welding with modified electrodes, evaluating the influence of these changes in the produced microstructures and in the mechanical properties of the resulting weld, and comparing the obtained results with the standard welding procedures and with the recently developed waterproof electrodes. The results obtained in most samples welded with modified electrodes showed increased mechanical resistance and increased tenacity due to the increased percentage of acicular ferrite in metal deposited without significant elevation of hardness, when compared with the traditional welding with AWS E7018 electrode and with ELBRÁS BRH4R waterproof electrode. The diffusing hydrogen measured in the modified electrodes was kept inside the parameters defined by international codes.