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Tratamentos de prevenção e proteção anticorrosivas para estruturas metálicas
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| 5.4 MB | Adobe PDF |
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Abstract(s)
A corrosão das estruturas metálicas tem acarretado elevados custos de prevenção, reparação e substituição, sendo que este é um dos problemas mais relevantes no ramo da construção civil. Esta dissertação pretende contribuir para o aumento conhecimento na Região Autónoma da Madeira (RAM) do fenómeno da corrosão e das técnicas de prevenção e proteção anticorrosivas.
Numa fase inicial é introduzido o tema “metais” onde são apresentadas as suas principais caraterísticas, os elementos de carácter metálico presentes na tabela periódica e como as suas propriedades atómicas influenciam o seu comportamento e os tipos de estrutura atómica que constituem os metais e a sua classificação.
Posteriormente é descrito o problema da corrosão com a apresentação dos vários mecanismos da corrosão. São também apresentadas algumas formas de previsão da taxa de corrosão, os fenómenos em que o produto da corrosão tem propriedades benéficas através da passivação, e apontados os tipos de corrosão mais comuns e a sua forma de apresentação. São ainda indicados os fatores de maior relevância que influenciam a corrosão.
Continuamente, é desenvolvido o tema principal desta dissertação, os métodos possíveis de prevenção e proteção das estruturas metálicas desde os mais primários que se iniciam na metalurgia até os processos mais elaborados através de corrente elétrica, passando também pelos diversos tipos de revestimentos possíveis para os metais. São também assinalados alguns dos problemas inerentes aos métodos e algumas formas de minimização.
Finalmente, é analisado um caso prático, onde foi aplicado um dos tipos de proteção existentes e medida a degradação deste tipo de revestimento ao longo do tempo através de alguns ensaios presentes nas normas EN NP ISO. Além disso, foram comparadas diversos cenários de manutenção para a estrutura em questão de modo a encontrar a solução mais viável em termos económicos, em termos de durabilidade, do desgaste em geral da estrutura, e apresentação visual.
Os resultados permitiram concluir que entre os diversos cenários apresentados, a importância do estado do substrato metálico antes da aplicação do revestimento em relação a outros fatores como a espessura a aplicar, é fulcral num sistema anticorrosivo, a longo prazo.
The corrosion in metal structures represents high costs in prevention, reparation and replacing, therefore this represents one of the most relevant problems in civil construction. This dissertation intends to contribute for greater understanding in the Autonomous Region of Madeira (ARM) regarding the phenomenon of corrosion and the anticorrosive techniques for prevention and protection. In an initial stage, the topic “metals” is introduced and presented it´s main characteristics, also the metallic elements in the periodic table, including their atomic properties which influence their behavior, and the types of atomic strutures that form the metals followed by their classification. Afterwards, brings the description of the problem of corrosion introducing the various corrosion mechanisms. Then are showed some forms to estimate the rate of corrosion, the phenomenon which the product of corrosion has positive consequences by passivation, and the most common types of corrosion and it´s way of emergence. Still there are indicated the most revelance factors that influence corrosion. Continuously it is developed the main topic of this dissertation where arises the possible methods of prevention and protection of metallic structures, starting with the most basic in metallurgy to the most elaborate through electric current, followed by the various types of coatings possible to metals. It´s also highlighted some of the problems regarding these methods and some ways to minimyze it´s effects. Finally, a case study was analyzed where one of the methods of protection was applied and the degradation in this coating was measured through time using some simple tests presented by EN NP ISO Standards. Besides this, several alternatives and solutions for conservation of the case study metal structure were compared in order to find the most viable solution in terms of economic, durability, appearance, abrasion and wear of the structure. The results allowed to conclude that between various scenarios presented, the importance of metallic substrate cleansing before the introduction of the prevention method, like other important factors as film thickness, considered key in noncorrosive sistems, on a long term.
The corrosion in metal structures represents high costs in prevention, reparation and replacing, therefore this represents one of the most relevant problems in civil construction. This dissertation intends to contribute for greater understanding in the Autonomous Region of Madeira (ARM) regarding the phenomenon of corrosion and the anticorrosive techniques for prevention and protection. In an initial stage, the topic “metals” is introduced and presented it´s main characteristics, also the metallic elements in the periodic table, including their atomic properties which influence their behavior, and the types of atomic strutures that form the metals followed by their classification. Afterwards, brings the description of the problem of corrosion introducing the various corrosion mechanisms. Then are showed some forms to estimate the rate of corrosion, the phenomenon which the product of corrosion has positive consequences by passivation, and the most common types of corrosion and it´s way of emergence. Still there are indicated the most revelance factors that influence corrosion. Continuously it is developed the main topic of this dissertation where arises the possible methods of prevention and protection of metallic structures, starting with the most basic in metallurgy to the most elaborate through electric current, followed by the various types of coatings possible to metals. It´s also highlighted some of the problems regarding these methods and some ways to minimyze it´s effects. Finally, a case study was analyzed where one of the methods of protection was applied and the degradation in this coating was measured through time using some simple tests presented by EN NP ISO Standards. Besides this, several alternatives and solutions for conservation of the case study metal structure were compared in order to find the most viable solution in terms of economic, durability, appearance, abrasion and wear of the structure. The results allowed to conclude that between various scenarios presented, the importance of metallic substrate cleansing before the introduction of the prevention method, like other important factors as film thickness, considered key in noncorrosive sistems, on a long term.
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Keywords
Corrosão Estrutura metálica Película Proteção Revestimento Tratamento Corrosion Metallic structure Film Protection Coating Procedure Engenharia Civil . Faculdade de Ciências Exatas e da Engenharia