Corrosion protection of carbon steel using a combination of Zr conversion coating and subsequent zinc-rich silicate coating with a flake ZnAl alloy

• Published in: Arabian journal of chemistry Vol. 15; no. 6; p. 103815
• Main Authors: Hoang, Nguyen, Khoa, Truong Anh, Nhung, Le Thi, Phuong, Phan Minh, Hang, To Thi Xuan, Chi, Nguyen Van, Nguyen, Thanh-Danh
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2022; Elsevier
• Subjects: Corrosion; Flake ZnAl pigments; Silicate coating; Zinc-rich coating; Zirconium conversion; Silicate coating; Flake ZnAl pigments; Zinc-rich coating; Corrosion; Zirconium conversion
• ISSN: 1878-5352; 1878-5379
• DOI: 10.1016/j.arabjc.2022.103815

To improve the corrosion protection properties of zinc-rich silicate coatings on steel, zirconium pretreatment loaded with (3-aminopropyl)triethoxysilane (APTES) 0.025 % (v/v) and the partial replacement of spherical zinc by flake ZnAl alloy were investigated. DC polarization and electrochemical impedance spectroscopy (EIS) show that the zirconium pre-treated layer containing APTES improves the corrosion protection of the bare steel. Zinc-rich silicate coatings containing flake ZnAl with and without pretreatment were evaluated by EIS, salt spray test and pull-off test. Pretreatment with a zirconium conversion layer reduces corrosion products and adhesion loss (from 16.53% to 12.54%) while the performance of corrosion protection significantly increased from 2003 Ω.cm2 to 2640 Ω.cm2 in comparison with the non-pretreated samples. The results show that flake ZnAl pigment (5 wt%) significantly improves corrosion resistance and prolongs the duration of cathodic protection of zinc-rich silicate coatings.