| 摘要: |
| 为定性比较添加剂对涂层防腐性能的作用，通过恒压微弧氧化（MAO）方法在AZ31B镁合金表面制备氧化陶瓷膜，采用扫描电子显微技术（SEM）、中性盐雾试验（NSS）等手段，考察了KOH及添加剂Na2B4O7、C6H5Na3O7和EDTA-2Na浓度（质量浓度）对MAO膜表面形貌、防腐性能、粗糙度和厚度的影响。结果表明：单一组分Na2SiO3电解液因较高起弧电压而未能在260 V恒压条件下获得具有“火山口”形貌特征的MAO膜，其防腐性能较差。适量KOH因较低微弧等离子体诱发电压和OH−较快的放电作用，提高了涂层的防腐性能。在优化的Na2SiO3-KOH体系中引入10~15 g/L Na2B4O7，因其特殊的形成过程及其“火山喷射状”的微结构，且获得的MAO膜具有自封孔结构，提高了其对镁合金的点腐蚀防护性能。C6H5Na3O7和EDTA-2Na具有抑弧效应，获得的MAO膜表面微孔分布均匀，但降低了MAO膜的厚度、粗糙度以及防腐性能。 |
| 关键词: 镁合金 微弧氧化 添加剂 耐蚀性 粗糙度 |
| DOI：10.11933/j.issn.1007-9289.20170917001 |
| 分类号:TG174.451 |
| 基金项目:四川省科技支撑计划（2016JZ0032）；四川省青年科技创新研究团队项目（2016TD0024）；四川理工学院人才引进基金（2017RCL15） |
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| Surface Morphology and Anti-corrosion of Micro-arc Oxidation Coatings with Different Additives |
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CUI Xue-Jun, PING Jing, DOU Bao-Jie, FU Qing-Shan, LIN Xiu-Zhou
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School of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong 643000, Sichuan
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| Abstract: |
| To compare the effects of additives on the anti-corrosion of coatings, micro-arc oxidation (MAO) coatings were developed on AZ31B magnesium alloy via constant voltage method. The effects of the concentration of potassium hydroxide (KOH) and the additives such as borax (Na2B4O7), sodium citrate (C6H5Na3O7), and ethylenediamine tetraacetic acid disodium (EDTA-2Na) on surface morphology, anti-corrosion, thickness, and roughness of the MAO coated samples were evaluated by scanning electron microscopy (SEM), neutral salt spray test (NSS), thickness gauge, and roughometer, respectively. The results show that the MAO coating with a crater shape is not observed under constant voltage of 260 V in single component Na2SiO3 because of its high arc voltage, showing poor anti-corrosion of Mg alloy. The corrosion resistance of MAO coatings is improved when KOH is added in Na2SiO3 solution, which can be attributed to the low arc voltage and fast discharge role of OH–. The self-sealing MAO coated samples prepared in the electrolyte solution containing borax of 10-15 g/L appear pitting corrosion resistance due to its morphological characteristics of volcano eject and formation process. Inversely, these samples produced in the electrolyte solution containing C6H5Na3O7 and EDTA-2Na show lower thickness and roughness, as well as poor corrosion resistance though exhibiting smaller micro porous with uniform distribution. |
| Key words: magnesium alloys micro-arc oxidation additive corrosion resistance roughness |
