Self-assembly of SiO₂ films on aluminum flakes for corrosion protection

Qixing Zhang, Weiming Zhou, Ibrahim Lawan, Samuel Etuk, Mingxin Zhang, Zaharaddeen N. Garba, Gerard Fernando, Zhanhui Yuan

Abstract

Thin and dense films are required to protect aluminum flakes in waterborne coatings from corrosion while maintaining their luster. We herein report the preparation of a self-assembled SiO₂ film from tetraethoxysilane (TEOS) using acid- and alkali-catalyzed sol-gel processes. The different SiO₂ structures formed under acid and alkali catalysis assembled into a compact SiO₂ film on the aluminum flakes, imparting corrosion resistance and stability under acidic conditions. The self-assembled film obtained when the acid-catalyzed process was performed before the alkali-catalyzed process was superior to that obtained when the sequence was reversed. This film was also significantly denser than the single coatings obtained from acid or alkali catalysis alone. FTIR, XRD, BET, SEM, TG, and theoretical calculations confirmed the formation of a dense film via the self-assembly of different types of SiO₂ particles. This process may also be applicable to the formation of colored aluminum flakes via coating with other metal oxides.

Keywords

Acid-catalyzed, alkali-catalyzed, anticorrosion, coating sequence, self-assembly, SiO₂

Adsorption Link:

https://www.tandfonline.com/doi/abs/10.1080/00986445.2020.1852399?journalCode=gcec20

20-CEC-Self-assembly of SiO2 films on aluminum flakes for corrosion protection.pdf