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| Micro-zone Electrochemical Behavior of AerMet100 Steel in Salt Spray Environment under Cl- |
| Received:April 14, 2019 Revised:May 19, 2019 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2019.10.015 |
| KeyWord:AerMet100 steel salt spray experiment micro-zone electrochemical test corrosion morphology corrosion products scanning Kelvin probe |
| Author | Institution |
| QIAN Ang |
Naval Aviation University Qingdao Campus, Qingdao , China |
| YANG Xiao-hua |
Naval Aviation University Qingdao Campus, Qingdao , China |
| JIN Ping |
Naval Aviation University Qingdao Campus, Qingdao , China |
| TAN Xiao-ming |
Naval Aviation University Qingdao Campus, Qingdao , China |
| WANG De |
Naval Aviation University Qingdao Campus, Qingdao , China |
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| Abstract: |
| Objective To research on the corrosion and micro-zone electrochemical behavior of AerMet100 steel under Cl-action in salt spray environment. Methods The corrosion morphology and corrosion products of AerMet100 steel were researched and analyzed through salt spray corrosion test. After the salt spray test of different duration, the potential distribution of the sample surface was obtained through the SKP test; the distribution of Kelvin potential on the sample surface was scanned and its changes were analyzed by Gauss fitting. Results The corrosion behavior of AerMet100 steel in salt spray corrosion test started from pitting corrosion and gradually developed to uniform corrosion; the corrosion products of AerMet100 steel were divided into two layers:loose outer layer and dense inner layer; due to the formation of large amounts of iron oxides and hydroxyl oxides during the corrosion reaction, the inner and outer corrosion products contained a large number of Fe and O elements. Both the inner and outer rust layers contained a small amount of Cl-, indicating that Cl-participated in the corrosion reaction process. The presence of alloying elements such as Cr, Co and Ni in the inner and outer rust layers made the rust layer ion-selective and dense, and accelerated the generation of the rust layer. The potential distribution on the un-corroded sample surface was relatively uniform and highly concentrated, which meant that the potential difference was small. The overall potential difference was 152 mV; and a small amount of surface active points were randomly distributed. At this time, the cathode and anode distribution of the sample surface were irregular. After 3 days of the salt spray test, the potential of the sample surface was positively shifted; the distribution tended to be dispersed; the potential difference was increased; and the overall potential difference was 270 mV, resulting in obvious cathode area and anode area. Corrosion occurred gradually because the Cl- adsorbed near the surface activity point of the sample destroyed the oxide film on the surface. After 6 days of salt spray test, the potential of the sample surface was further increased; the distribution was more dispersed; the potential difference was slightly reduced; and the overall potential difference was 180 mV. Due to the continuous expansion of the corrosion product layer, the sample surface was significantly divided into larger cathode and anode areas. Conclusion The corrosiveness of C- destroys the oxide film on the surface of the matrix, causing the corrosion of AerMet100 steel at the inclusions. Corrosion products can hinder the penetration of Cl- and have a protective effect on the matrix. |
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