PRÉ-TRATAMENTO POR DEPOSIÇÃO ELETROASSISTIDA DE VINILTRIETOXISSILANO (VTES) PARA A PINTURA DE ALUMÍNIO
PRETREATMENT FOR PAINTING ALUMINUM BY ELECTRO-ASSISTED DEPOSITION OF VINYLTRIETHOXYSILANE (VTES)
Moreira, Vitor Bonamigo; Ferreira, Jane Zoppas; Meneguzzi, Álvaro
Resumo
A técnica de deposição eletroassistida pode conduzir à formação de filmes de organossilanos mais contínuos pelo método de sol-gel. A técnica baseia-se na promoção da eletrólise da água para aumentar o pH na região catódica, o que acelera as reações de condensação do precursor organossilano no cátodo e resulta em filmes reticulados que cobrem o substrato mais homogeneamente em comparação à técnica de imersão simples. Neste estudo utilizou-se viniltrietoxissilano (VTES) como precursor no método de sol-gel para a produção de revestimentos pela técnica de deposição eletroassistida como pré-tratamento para a pintura de alumínio com verniz poliuretânico. Tais revestimentos foram comparados à cromatização e à técnica de imersão simples por ensaio de corrosão acelerada em névoa salina e medida de aderência de revestimento orgânico e foram caracterizados morfologicamente por MEV e EDS. Os resultados indicam que a deposição eletroassistida promove a formação de filmes protetores mais homogêneos e propicia o aumento da aderência do verniz utilizado.
Palavras-chave
Abstract
The electro-assisted deposition technique may lead to more continuous silane films by the sol-gel method. This technique is based on promoting water electrolysis to increase the pH on the cathodic region, which accelerates the silane condensation reactions on the cathode and results in crosslinked films that cover the substrate more homogeneously in comparison to the dip-coating technique. In this study, vinyltriethoxysilane (VTES) was used as a precursor in the sol-gel method for the production of coatings by electro-assisted deposition as a pretreatment for painting aluminum with polyurethane varnish. These coatings were compared to chromate and dip-coating pretreatments by salt spray test, paint adhesion measurement and were morphologically analyzed by SEM and EDS. The results indicate that the electro-assisted deposition technique leads to the formation of more homogeneous protective films and improves the adherence of the tested varnish.
Keywords
Referências
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