|
| Effect of AC Interference on Failure Mechanism of Zinc-rich Epoxy Coatings in Different Environments |
| Received:February 03, 2021 Revised:March 04, 2021 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.07.015 |
| KeyWord:AC interference zinc-rich epoxy coating EIS zinc powder activation cathodic protection |
| Author | Institution |
| JIANG Jie |
CNPC EastChina Design Institute Co., Ltd, Qingdao , China |
| XU Tian |
CNPC EastChina Design Institute Co., Ltd, Qingdao , China |
| LIU Jing |
CNPC EastChina Design Institute Co., Ltd, Qingdao , China |
| YANG Chao |
Postdoctoral Scientific Research Workstation of Shengli Oilfield Company, Dongying , China;Technology Inspection Center of Shengli Oilfield, SINOPEC, Dongying , China |
| CUI Gan |
China University of Petroleum East China, Qingdao , China |
|
| Hits: |
| Download times: |
| Abstract: |
| This paper aims to reveal the failure mechanism of Zn-rich epoxy coating under the condition of high hydroxyl ion concentration and AC interference. Zn-rich epoxy coating was selected as the research object. X80 steel was used as matrix, the coated X80 sample was formed manually and the coating thickness was determined to be (25±5) μm by five-point test. The EIS of the coated X80 sample in 3 wt.% NaOH solution with immersion time was studied with / without AC interference, and the failure evolution mechanism of Zn-rich epoxy coating was established. In alkaline environment, zinc powder was more advantageous to the activation, but also had faster reaction rate, which contributed to Zn(OH)2 and Zn(OH)42－quickly covered the activated zinc power to prevent electrical connection. Meanwhile, Fe in alkaline environments was prone to passivation, greatly weakened the wet adhesion strength of coating and metal matrix. Similarly, the reaction process of activated zinc powder was very rapid due to AC voltage, so that effective electrical connection and cathodic protection cannot be formed. AC interference can inhibit the activation process of zinc particles (ZnO→Zn(OH)2/Zn(OH)42–), promote the reaction process of activating zinc particles, leading to a weaker cathodic protection of zinc. |
| Close |
|
|
|