外加电位对Monel400合金海水环境腐蚀磨损性能的影响

Effect of Applied Potential on the Tribocorrosion Behaviors of Monel 400 Alloy in Seawater

目的研究不同恒电位对Monel400合金海水环境腐蚀磨损性能的影响。方法将试样加工成圆柱试样,通过设计的特殊夹具夹紧试样,利用摩擦试验机和电化学工作站做不同恒电位下的磨蚀实验,通过开路电位极化曲线的变化评价合金的电化学性能,通过磨损量的变化评价合金的摩擦性能。通过扫描电镜揭示磨损机理,探讨交互作用机制。结果摩擦过程中的开路电位比静态腐蚀时的低。随着外加电位的增加,腐蚀电流密度增加,摩擦系数降低,总的体积损失量增加。腐蚀磨损存在明显的交互作用。结论摩擦能够破坏合金表面的钝化膜,导致具有更高电化学活性的新表面暴露于溶液中,因此促进了表面腐蚀。而腐蚀产生的腐蚀产物层比较粗糙和疏松,其剪切强度比基底合金低得多,因此当氧化铝块摩擦过合金表面时,很容易去除腐蚀产物层,进而促进了材料损失。腐蚀磨损条件下材料的损失量明显比纯磨损条件下的高。

The work aims to research the effects of different constant potentials on the tribocorrosion behaviors of Monel400 alloy in seawater. The samples were processed into cylindrical samples and clamped by the special fixtures designed. The abra-sion experiment under various constant potentials was carried out by friction testing machine and electrochemical workstation. The electrochemical performance of the alloy was evaluated based on the change in the open-circuit potential polarization curve. The friction property of the alloy was evaluated based on the change in the abrasion loss. The wear mechanism was revealed by scanning electron microscope and the interaction mechanism was discussed. The open-circuit potential in the friction process was lower than that in the static corrosion. As the applied potential increased, the corrosion current density increased, the friction coefficient decreased and the total volume loss increased. The corrosion and wear had obvious interaction. The friction can damage the passive film of the alloy surface, causing the new surface with higher electrochemical activity to be exposed to the solution; therefore, the surface corrosion is accelerated. The corrosive product layer generated by the corrosion is quite coarse and loose. Its shear strength is much lower than that of the base metal alloy. Therefore, when alumina block slides across the alloy surface, such layer is easily peeled off, finally resulting in the acceleration of material loss. The loss amount of materials under corrosion and wear is apparently higher than that under the pure wear.