镁合金表面有机防腐导电涂层的制备及性能研究

Preparation and Properties of Organic Anticorrosive Conductive Coating on Magnesium Alloy

目的通过在AZ31镁合金表面微弧氧化陶瓷层上制备有机导电涂层,实现其既防腐又导电的功能。方法加入无机导电炭黑制备涂料体系,在前期制备的微弧氧化层表面,应用刮涂法制备不同配比的有机防腐导电涂层。采用场发射电子显微镜观察涂层的微观形貌,用电化学方法测试涂层耐蚀性,用双电侧四探针测试仪测量涂层电阻值。结果有机物中添加无机导电炭黑颗粒,对材料形貌有较大影响,随导电颗粒的添加,涂层表面质量下降,出现较多裂纹。与只有微弧氧化涂层的材料相比,其腐蚀电位提高了0.6~0.68 V。导电炭黑能有效地改善涂层的导电性,当炭黑添加量为10%时,涂层的平均电阻仅为70?。结论有机涂层由于封孔和惰性反应作用,能进一步提高微弧氧化涂层的耐蚀性,由于导电炭黑颗粒的隧道效应及导电网络作用,使得涂层导电性大幅提高。

The work aims to prepare organic conductive coating on the micro-arc oxidation ceramic layer on the surface of the magnesium alloy(AZ31) to achieve the function of corrosion prevention and conduction. On the surface of the micro-arc oxidation layer prepared in the previous stage, inorganic conductive carbon black was added, and different ratios of organic anti-corrosion conductive coatings were prepared by knife coating method. The microscopic morphology of the coating was observed by field emission electron microscopy, the corrosion resistance of the coating was tested electrochemically, and the coating resistance was measured by a four-electrode four-probe tester. The addition of inorganic conductive carbon black particles to the organic matter had a great influence on the morphology of the material. With the addition of conductive particles, the surface quality of coating decreased and more cracks appeared. Compared with the material with only micro-arc oxidation coating, the corrosion potential was increased by 0.6~0.68 V. The conductive carbon black could effectively improve the conductivity of the coating and when the carbon black was added in an amount of 10 wt.%, the average resistance of the coating was only 70 Ω. Due to the sealing and inert reaction, the organic coating can further improve the corrosion resistance of the micro-arc oxidation coating. Due to the tunneling effect of the conductive carbon black particles and the conductive network, the conductivity of the coating is greatly improved.