| YANG Yuancheng,WANG Youbin,ZHAO Jinwei,ZHOU Jiashun,FENG Jiqiang,GAO Feng,WEI Yuezhou.Effect of Zn5(OH)8Cl2 in Corrosion Products on Corrosion Behaviour of Pure Zn[J],53(4):98-109, 151 |
| Effect of Zn5(OH)8Cl2 in Corrosion Products on Corrosion Behaviour of Pure Zn |
| Received:December 08, 2022 Revised:May 06, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.04.009 |
| KeyWord:corrosion products Zn5(OH)8Cl2 pure Zn in-situ growth corrosion protection |
| Author | Institution |
| YANG Yuancheng |
State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,School of Resources, Environment and Materials, Guangxi University, Nanning , China |
| WANG Youbin |
State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,School of Resources, Environment and Materials, Guangxi University, Nanning , China |
| ZHAO Jinwei |
State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,School of Resources, Environment and Materials, Guangxi University, Nanning , China |
| ZHOU Jiashun |
State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,School of Resources, Environment and Materials, Guangxi University, Nanning , China |
| FENG Jiqiang |
State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,School of Resources, Environment and Materials, Guangxi University, Nanning , China |
| GAO Feng |
State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,School of Resources, Environment and Materials, Guangxi University, Nanning , China |
| WEI Yuezhou |
School of Nuclear Science and Technology, University of South China, Hunan Hengyang , China |
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| Abstract: |
| The effect of the complex corrosion product film on the corrosion resistance of Zn has been studied by many researchers in recent years. However, the effect of certain corrosion product on the corrosion resistance of substrate has not been explained clearly. Simonkolleite (Zn5(OH)8Cl2, ZHC) is one of the corrosion products of Zn and its alloys. Most researchers believe that the corrosion product film containing ZHC can improve the anti-corrosion performance of the substrate, but the impact of ZHC on the anti-corrosion performance of the substrate is not very detailed. Therefore, this work aims to explore the effect of the ZHC on the corrosion protection performance of pure Zn, and the corrosion protection mechanism of ZHC film on pure Zn. The ZHC film was prepared on the surface of pure Zn by in-situ growth method. The phase and microstructure of the corrosion products on the surface of specimens were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The effect of ZHC on the corrosion protection performance of pure Zn was analyzed with potentiodynamic polarization curve (Tafel) and electrochemical impedance spectroscopy (EIS). It was found that the dense and fine layer of ZHC nanoflakes was formed on the surface of pure Zn, covering the entire surface of pure Zn. Then, the second layer of large size ZHC nanosheets was formed on the first layer of ZHC. The results of the polarization curve showed that the ZHC could reduce the corrosion current density of pure Zn from 78.23 μA/cm2 to 2.08 μA/cm2, and make the corrosion potential move to the positive potential from ‒1.050 V (vs. SCE) to ‒0.998 V (vs. SCE), and with the increase of preparation time, cathode slope (βc) gradually increased, which indicated that ZHC could effectively hinder the charge transfer, inhibit the cathodic oxygen reduction, slow down the corrosion rate of pure Zn and provide corrosion protection for pure Zn. The results of the XRD and SEM showed that the ZHC could inhibit the formation of the corrosion product hydrozincite (Zn5(CO3)2(OH)6, HZ) and reduce the formation of flocculent corrosion products in the immersion corrosion process. During the short-term immersion, the impedance value of pure Zn gradually increased with the pre-prepared ZHC, which was due to the fact that the generated corrosion products filled the gaps in the ZHC nanosheets, making the corrosion product film dense and effectively hindering the contact between the corrosion medium and pure Zn, and the ZHC film could provide better protection for the Zn substrate. During the long-term immersion process, the impedance value of ZHC/Zn decreased, due to the cracks of the ZHC film, providing a new corrosion channel and leading to a decrease in the protective effect of the ZHC film on pure Zn. To sum up, ZHC film can slow down the corrosion rate of pure Zn. Through comparison between the corrosion behavior of pure Zn and ZHC/Zn during immersion corrosion, in the early stage of immersion, it can be seen that the corrosion protection performance of pure Zn increases with the increasing amount of ZHC. In the long-term immersion, it can be seen that the corrosion protection effect of ZHC film on pure Zn gradually decreases. |
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