Estudos da preparação de superfície da liga AA6063T5 e do desenvolvimento de revestimentos híbridos orgânico-inorgânicos a base de siloxano-PMMA para aplicação anticorrosiva
Carregando...
Data
2010-09-23
Autores
Teixeira, Dilton Gonçalves [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho está basicamente dividido em duas partes. A primeira está relacionada à limpeza da superfície da liga de alumínio AA6063T5 e sua influência na proteção contra a corrosão. A segunda parte se refere à preparação de revestimentos híbridos orgânicoinorgânico pelo processo sol-gel e deposição sobre a superfície da liga de alumínio por dipcoating. Três amostras de liga AA6063T5 foram investigadas: como recebida, debastada e polida mecanicamente e tratada quimicamente. O tratamento mecânico foi realizado utilizando lixas SiC de granulometria 320 a 4000 e o químico foi realizado utilizando uma solução aquosa contendo uma mistura de hidróxido, sulfato e cloreto de sódio. Todas as amostras foram caracterizadas fisicamente por difratometria de raios X (XRD), medidas de dureza, microscopia eletrônica de varredura (SEM) e microscopia óptica (MO), e por medidas de potencial de circuito aberto (OCP) e espectroscopia de impedância eletroquímica (EIS) em solução 3,5% NaCl. As imagens SEM mostraram que a presença de partícula intermetálicas na superfície da liga diminui após o tratamento químico comparado ao tratamento mecânico. Os resultados de EIS mostraram que o tratamento químico oferece maior resistência à corrosão do que as submetidas aos outros tratamentos, porque o ataque alcalino utilizado dissolveu a maioria dos precipitados contendo Fe ou Cu, elementos responsáveis por sítios catódicos. A lavagem com HNO3 pela qual passou a amostra tratada quimicamente provavelmente reforçou a camada de óxido, tornando a superfície da liga mais resistente ao ataque por cloreto. Os revestimentos híbridos foram somente depositados na liga que recebeu tratamento químico. Esses filmes híbridos foram preparados com tetraetoxi-silano (TEOS) e 3-metacriloxipropril trimetoxi silano (MPTS), pela hidrólise e policondensação em meio ácido seguido por...
This work is basically divided in two parts: the first one is related to the surface treatment of AA6063T5 aluminum alloy and its influence on the protection against corrosion. The second concerns to the preparation of organic-inorganic hybrid coatings by the sol-gel process that were deposited on the aluminum alloys by dip-coating. Three samples of AA6063T5 aluminum alloys were investigated, the as-received one, after mechanical and chemical treatment, respectively. The mechanical treatment was realized using SiC paper grades 320 to 4000 and the chemical one was done by an aqueous solution containing a mixture of sodium hydroxide, chloride and sulfate. All samples were physically characterized by X-ray diffractometry (XRD), hardness measurements, scanning electron microscopy (SEM) and optical microscopy (OM), and electrochemically by open circuit measurements (OCP) and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The SEM images depicted that the presence of intermetallic particles on the alloy surface decreased after the chemical treatment compared to the mechanical one. The EIS results showed that the sample chemically treated possesses a higher corrosion resistance than those obtained using other procedures. EIS results showed that the chemically treated sample presented higher corrosion resistance than the ones submitted to other procedures. The alkaline treatment dissolves the great part of precipitates containing iron or copper, which are responsible by the cathodic sites formation. The washing of the sample with nitric acid solution after the alkaline treatment removes impurities from the surface and can give to the oxide layer higher resistance against the action of the chloride ion. The hybrid coatings were only deposited on the alloy that received the chemical treatment. Hybrid films containing tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimetho... (Complete abstract click electronic access below)
This work is basically divided in two parts: the first one is related to the surface treatment of AA6063T5 aluminum alloy and its influence on the protection against corrosion. The second concerns to the preparation of organic-inorganic hybrid coatings by the sol-gel process that were deposited on the aluminum alloys by dip-coating. Three samples of AA6063T5 aluminum alloys were investigated, the as-received one, after mechanical and chemical treatment, respectively. The mechanical treatment was realized using SiC paper grades 320 to 4000 and the chemical one was done by an aqueous solution containing a mixture of sodium hydroxide, chloride and sulfate. All samples were physically characterized by X-ray diffractometry (XRD), hardness measurements, scanning electron microscopy (SEM) and optical microscopy (OM), and electrochemically by open circuit measurements (OCP) and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The SEM images depicted that the presence of intermetallic particles on the alloy surface decreased after the chemical treatment compared to the mechanical one. The EIS results showed that the sample chemically treated possesses a higher corrosion resistance than those obtained using other procedures. EIS results showed that the chemically treated sample presented higher corrosion resistance than the ones submitted to other procedures. The alkaline treatment dissolves the great part of precipitates containing iron or copper, which are responsible by the cathodic sites formation. The washing of the sample with nitric acid solution after the alkaline treatment removes impurities from the surface and can give to the oxide layer higher resistance against the action of the chloride ion. The hybrid coatings were only deposited on the alloy that received the chemical treatment. Hybrid films containing tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimetho... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Físico-química, Corrosão, Aluminium alloy, Hybrid coatings
Como citar
TEIXEIRA, Dilton Gonçalves. Estudos da preparação de superfície da liga AA6063T5 e do desenvolvimento de revestimentos híbridos orgânico-inorgânicos a base de siloxano-PMMA para aplicação anticorrosiva. 2010. 122 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química de Araraquara, 2010.