Protective PMMA-silica coatings for aluminum alloys: Nanostructural control of elevated thermal stability and anticorrosive performance

Autor(es)

dos Santos, Fabio Cesar ^[1] ; Pulcinelli, Sandra Helena ^[1] ; Santilli, Celso Valentim ^[1] ; Hammer, Peter ^[1]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ UNESP, Inst Chem, BR-14800060 Araraquara, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Progress in Organic Coatings; v. 152, MAR 2021.
• Citações Web of Science: 0

Resumo

Organic-inorganic hybrid coatings for corrosion protection of aluminum alloys are promising alternatives to the current methods based on chromate passivation. This study examined the role of the polymer/silica ratio in terms of the hybrid nanostructure formed and its effect on the thermal stability and anticorrosive performance of the polymethyl methacrylate (PMMA)-siloxane-silica hybrid coatings. The chemical and nanostructural properties of the hybrid coatings assessed using Fourier transform infrared (FTIR) and small angle X-ray scattering (SAXS) were correlated with the thermal stability evaluated by thermogravimetry (TGA) and corrosion protection evaluated by electrochemical impedance spectroscopy (EIS) in saline/acid solution (NaCl 3.5 % HCl pH 3). TGA showed that the high thermal stability (up to 287 degrees C) of the hybrid formulations with lower silica fractions is related to the adequate size and spacing of the siloxane nodes in the embedding polymer matrix. Correlation of SAXS and EIS measurements allowed to identify the specific molar ratios and nanostructural configuration in which the polymer and siloxane-silica nodes ideally combine forming thin PMMA-silica coatings (2-5 mu m) that present long-term stability (> 6 months) with a corrosion resistance of up to 25 G Omega cm(2), being approximately 7 orders of magnitude higher than that of the uncoated Al2024-T3 substrate. (AU)

• Processo FAPESP: 14/09547-5 - Estudo da influência das condições de síntese nas propriedades de híbridos orgânico-inorgânicos puros e modificados por Ce(IV)
• Beneficiário: Fábio Cesar dos Santos
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 16/02201-1 - Estudo por absorção de raios-X da estrutura local e propriedades eletrônicas de revestimentos híbridos orgânico-inorgânicos dopados com cério
• Beneficiário: Fábio Cesar dos Santos
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado