锂含量对镁锂合金表面碳酸锂膜层耐蚀性的影响

Effect of Li Content on Corrosion Resistance of Lithium Carbonate Coating on Mg-Li Alloys

摘要:

利用低温等离子体在LAZ141镁锂合金表面制备绿色环保且高耐蚀的碳酸锂膜层是一种全新的镁锂合金表面处理技术,为进一步探索合金中Li含量对所形成的碳酸锂膜层结构及耐蚀性能的影响,本文采用SEM、EDS、EIS和析氢测试等方法对不同Li含量镁锂合金的碳酸锂膜层进行了表征和分析。研究结果表明：合金基体中Li含量决定了膜层中Li₂CO₃成分的含量,当合金中Li含量达到10 wt. %以上时,膜层外层能够形成主要由Li₂CO₃成分构成的保护层；电化学测试及析氢结果表明,该保护层能够在0.6 M氯化钠溶液中将膜层阻值提高2个数量级以上并将析氢速率降低3倍以上。

Abstract:

An eco-friendly and high corrosion-resistant lithium carbonate coating was firstly fabricated on LAZ141 by low temperature plasma. To investigate effect of Li content on structure and properties of as-prepared coating, SEM, EDS, EIS and hydrogen evolution test were adopted for characterization and analysis. The results showed that the content of lithium carbonate in coatings were determined by Li content in alloys. A protective layer with a high ratio of Li₂CO₃ can be formed in the coating when the Li content in alloy reaches the value of 10 wt.%. Hydrogen evolution and EIS results in 0.6 M NaCl solution indicate that the protective layer can improve the resistance of coating over two order of magnitude and reduce the hydrogen evolution rate of substrate at least by 3 times.