New Insights in Adhesive Properties of Hybrid Epoxy-Silane Coatings for Aluminum Substrates: Effect of Composition and Preparation Methods

Author(s)

Coutinho Silva, Amanda Alvarenga ^[1] ; Gomes, Thayna Ipolito ^[1] ; Pereira Martins, Brenda Diane ^[1] ; Rivero Garcia, Renata Batista ^[2] ; Cividanes, Luciana De Simone ^[1] ; Kawachi, Elizabete Yoshie ^[1]

Affiliation

^[1] Inst Tecnol Aeronaut, Chem Dept, Praca Marechal Eduardo Gomes 50, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[2] Acad Forca Aerea, Estr Aguai S-N, BR-13631972 Pirassununga, SP - Brazil

• Document type: Journal article
• Source: Journal of Inorganic and Organometallic Polymers and Materials; v. 30, n. 8 FEB 2020.
• Web of Science Citations: 1

Abstract

The sol-gel system has attractive properties both in terms of adhesion to metal substrates and of its great potential to replace the toxic treatments of metal surface currently used, such as chromating and anodization. In this work, hybrid epoxy-silane coatings prepared by the sol-gel method with epoxy resin and tetraethoxysilane (TEOS) were evaluated for the metal-metal bonding of aluminum substrates, based on the influence of different compositions/preparation methods of the coatings in their physical-chemical and adhesive properties. Five variables were studied: time after preparation of the adhesive systems prior to the deposition, the composition of the coating layers, the addition of a silane compound (3-glycidoxypropyltrimethoxysilane-GPTMS), the addition of epoxy resin to the adhesive systems (with or without curing agent) and the pressing method (type C clamp or by marble plates). The samples were characterized by infrared spectroscopy (FT-IR), rheological analyzes (viscosity) and shear test. The FT-IR analysis showed that the presence of epoxy resin in the sol-gel system delayed the gel transition, at the same time that the presence of the sol-gel accelerated the epoxy resin curing process. The rheological analyses showed similar trends, and the viscosity of the epoxy resin and epoxy-sol systems increased after 60 min at 70 degrees C, while the sol-gel system showed an increase in viscosity after 20 min at 70 degrees C, indicating that this is the best moment for the deposition. The shear results showed that the system adhesion is stronger when silane is used as a coupling agent between the aluminum substrate and the epoxy resin, probably due to the Si-O-Al bonding and the good cohesion of the epoxy resin with the curing agent. (AU)

• FAPESP's process: 18/26447-5 - Synthesis and characterization of hybrid films obtained by sol-gel with addition of GPTMS and epoxy resin for aluminum adhesion
• Grantee: Amanda Alvarenga Coutinho Silva
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 19/13723-7 - Nanocomposite coatings obtained by sol-gel for adhesion and protection against corrosion of aluminum alloys
• Grantee: Luciana de Simone Cividanes Coppio
• Support Opportunities: Regular Research Grants