Preparation of superhydrophobic composite coating on 2024 aluminum alloy and its stability and corrosion resistance
Xiaoyun Qiu, Yuntao Wang
Abstract
2024 aluminum alloy is treated by anodic oxidation process. After that, the anodized aluminum is coated with ZnO particles sol to form a sol coating. Taking advantage of the porous characteristics of the anodized aluminum, the sol coating and the anodized aluminum are closely combined to construct a superhydrophobic composite coating after heating treatment. The experimental results show that the superhydrophobic composite coating has protrusions of various shapes and holes interlacedly distributed to form a micro-nano hierarchical structure, and its morphology is obviously different from that of the anodized aluminum. The superhydrophobic composite coating is composed of Al, O, S, Zn, Si and C elements. Meanwhile, Zn, Si and C elements are derived from the sol coating. The contact angle of the superhydrophobic composite coating reaches 151.2°, which has good resistance to wear and impact damage. The superhydrophobic composite coating has the lowest corrosion current density of 3.79 × 10−6 A/cm2, which is more than an order of magnitude lower than that of 2024 aluminum alloy substrate, showing good corrosion resistance. The superhydrophobic composite coating relies on the micro-nano hierarchical structure with low surface energy which can effectively block the intrusion of corrosive media and increase corrosion resistance to provide an ideal protection for 2024 aluminum alloy substrate.