基于镁粉活性调控的镁合金表面聚苯胺-镁粉长效复合防护涂层研究

Organic coatings are widely used in corrosion protection of Mg alloys due to their simple process and good protection performance. Mg-rich coating and polyaniline coating are two important development directions for organic coatings on Mg alloys. As Mg particles are rapidly consumed in Mg-rich coating and corrosive medium permeates rapidly in polyaniline coating, the life time of those two coatings are needed to be further prolonged. The research project will combine the complementary of polyaniline coating and Mg-rich coating. The Mg particles and their corrosion products will retard the permeation of corrosive medium in polyaniline coating; the HF-doped polyanilines will be used to enhance the conductivity among Mg particles or between Mg particles and Mg alloy substrates to give play to the cathodic protection of Mg particles; meanwhile, the formation of compact reaction products on Mg particles will be promoted by the oxidation-reduction reaction of the polyanilines to reduce the subsequent reactivity of Mg particles in order to prolong the cathodic protection period. Basing on the stannate pretreatment of Mg particles to reduce their initial reactivity and the initial coating defects, the associations between the Mg particles reactivity and the cathodic protection efficiency of Mg-rich coating will be proposed, the influence rules of the HF-doped polyanilines on the cathodic protection performance of Mg particles will be investigated, and the collaborative protection mechanism of the polyaniline-magnesium particles composite coating for Mg alloys will be revealed. Those research results will provide the scientific basis for the regulation of the Mg-rich coating for the different Mg alloys, enhance the protection performance of the Mg-rich coating on Mg alloys, and provide new ideas for the development of organic coatings for Mg alloys.

有机涂层工艺简单且防护性好，被广泛用于镁合金防腐。富镁涂层和聚苯胺涂层是两个重要的镁合金有机涂层发展方向，因镁粉迅速消耗或腐蚀介质快速渗透其寿命都有待进一步提高。本项目发挥两种涂层互补优势：以镁粉及反应产物阻缓聚苯胺涂层中腐蚀介质渗透；利用HF掺杂聚苯胺增强镁粉间、镁粉与镁合金基体间导电性以便发挥涂层中镁粉阴极保护功能；并利用聚苯胺氧化还原反应促进镁粉表面形成致密反应产物，降低镁粉后续反应活性以延长阴极保护周期。在锡酸盐改性镁粉降低初期反应活性以减少涂层早期缺陷基础上，明确镁合金表面涂层中镁粉活性与其阴极保护效率及防护周期关联规律；探究HF掺杂聚苯胺影响镁粉阴极保护性能机制；揭示聚苯胺-镁粉复合涂层对镁合金的协同防护机理；构筑镁合金表面HF掺杂聚苯胺-镁粉长效复合防护涂层。研究成果为针对镁合金活性差异调控富镁涂层提供科学依据；提高富镁涂层对镁合金防护性能；为镁合金有机涂层研制提供新的思路。

有机涂层工艺简单且防护性好，被广泛用于镁合金防腐。富镁涂层和聚苯胺涂层是两个重要的镁合金有机涂层发展方向，因镁粉迅速消耗或腐蚀介质快速渗透其寿命都有待进一步提高。本项目发挥两种涂层互补优势，首先，采用锡酸盐对富镁涂层中的纯镁颗粒进行预处理，经过20 min的锡酸盐预处理，纯美颗粒表面形成的锡酸镁保护膜层可降低纯镁的腐蚀速率，延长富镁涂层寿命；其次，锡酸盐预处理的富镁涂层中的腐蚀产物致密，增强涂层屏蔽性；最后，AZ91D镁合金基体表面形成锡酸镁保护膜，降低镁合金基体腐蚀速率，提高富镁涂层防护性。HF掺杂聚苯胺可改善纯镁颗粒与AZ91D镁合金间的电接触，增强阴极保护作用；促使镁的腐蚀产物为MgO和MgF2，改善涂层屏蔽作用；捕获部分氯离子，减缓涂层的劣化；在AZ91D镁合金基体表面形成保护膜，阻挡电解质的渗透，延缓基体腐蚀，显著增强富镁涂层防护性。