Corrosion Behavior of Zinc Covered with Native Oxides Under Thin Solution Films

Abstract

This study clarified the influence of native oxides on the atmospheric corrosion of Zn. The electrochemical impedance spectroscopy (EIS) values of native-oxide-covered Zn were measured under thin solution films of 10 μm to 500 μm in thickness. The native oxides were formed by exposing pure Zn plates to humidified air at two different temperatures, 25°C and 60°C, for the duration of one week. EIS was applied to the native-oxide-covered Zn for measurement under thin solution films; the results were analyzed using a transmission line equivalent circuit to determine the charge-transfer resistance (Rct). The native oxide formed at 25°C strongly suppressed the corrosion rate (1/Rct) of Zn, which was independent of the solution film thickness (Xf). However, the 1/Rct was not reduced by the native oxides formed at 60°C, as it was dependent on Xf. This paper discusses the different behaviors of the native oxides in the context of corrosion protection.

Morphology and corrosion behavior of ZnO passive films for galvanized steel applications: effects of anodizing parameters

“…P Spathis and I Poulios (1995) [19] investigated the corrosion and photo-corrosion of zinc anodic films prepared on zinc surface in borate electrolyte and reported that the film thickness is the key to protection of substrate zinc under illumination, however it has no effect in the dark. The report by C Somphotch et al (2020) [20] pointed out the importance of the thickness of electrolyte film on the surface of native ZnO film on its corrosivity, in which situation the amorphous ZnO films are more protective than crystalline ZnO films. Nevertheless, it is recognized from the above studies that galvanized steel has not yet been tested to distinguish the effects of anodizing parameters for their effects on anti-corrosion performance, and its relation to film thickness, morphological structures, and surface chemistry.…”