EIS and Salt-Spray study of AA2524 anodized in tartaric-sulfuric acid bath and protected with hybrid sol???gel coating

• Autor(a) principal: COSTENARO, HELLEN
• Data de Publicação: 2017
• Outros Autores: QUEIROZ, FERNANDA M., TERADA, MAYSA, PAINT, YOANN, RENAUD, ALEXIS, OLIVIER, MARIE-GEORGE, COSTA, ISOLDA, MELO, HERCILIO G. de, CONGRESSO BRASILEIRO DE CORROSAO, 36.; INTERNATIONAL CORROSION MEETING, 6th; CONCURSO DE FOTOGRAFIA DE CORROSAO E DEGRADA??AO DE MATERIAIS, 20.; EXPOSI??AO DE TECNOLOGIAS PARA PREVEN??AO E CONTROLE DA CORROSAO, 36.
• Tipo de documento: Artigo de conferência
• Título da fonte: Repositório Institucional do IPEN
• Texto Completo: http://repositorio.ipen.br/handle/123456789/27321
• topic: aluminium alloys; sol-gel process; coatings; corrosion protection; anodization; sulfuric acid; tartaric acid

AA2524 is a relatively new brand of aluminum alloy designed to build lightweight structural components in aerospace industry. To be employed in aircrafts, high strength Al alloys need to be protected from corrosion by a robust protection system. One of the steps applied in the protection protocol is anodizing, which is known to greatly improve the corrosion resistance of Al alloys. In the present investigation, a sol-gel hybrid layer was applied as a post-treatment step for anodized AA2524 and the corrosion resistance of the system evaluated by means of EIS measurements and salt-spray tests. The anodizing process was performed in a tartaric-sulfuric acid (TSA) bath, which is more environmentally friendly than the traditional chromic acid anodizing baths, and the sol???gel solution was prepared by mixing tetraethoxysilane (TEOS) and 3-glycidyloxypropyl-trimethoxysilane (GPTMS) precursors in a solution with high water content. For comparison reasons, TSA anodized samples were also hydrothermally sealed in boiling deionized water. The results of both EIS and salt-spray tests demonstrated superior corrosion resistance for the anodized samples post-treated with the hybrid sol-gel layer. Electrical equivalent circuit fitting of the EIS data indicated that the hybrid sol-gel layer strongly hinders electrolyte penetration through the porous layer, better protecting the underlying substrate.