交变压力对无溶剂环氧涂层在模拟超深海环境下的电化学行为

Effect of Alternating Pressure on Electrochemical Behavior of Solvent-free Epoxy Coating in Simulated Ultra-deep Sea Environment

通过EIS和LEIS对环氧粉末涂层和无溶剂环氧液体涂层分别在模拟超深海环境中0.1~20和0.1~30 MPa交变压力腐蚀环境下浸泡480 h的失效行为进行了研究,分析了超深海交变压力对涂层耐腐蚀性能的影响,并利用SEM观察了浸泡后涂层/Q345钢界面的表面形貌。研究表明,两种涂层在0.1~30 MPa交变压力作用下涂层的失效过程较为明显,环氧粉末涂层在0.1~30和0.1~20 MPa交变压力浸泡480 h后涂层阻抗值分别下降了2个和1个数量级,无溶剂环氧液体涂层在同样环境下浸泡后阻抗值分别下降了3个和2个数量级,说明了环氧粉末涂层在交变压力条件下对Q345的保护性能更优,阻绝离子渗透能力更强。从LEIS结果分析出在较高交变压力下,涂层微观局部腐蚀扩散速率更快。

The failure behavior of epoxy powder coating and solvent-free epoxy liquid coating in simulated ultra-deep-sea environment for 480 h was studied by means of EIS and LEIS, while by applied alternating pressures within ranges 0.1-20 and 0.1-30 MPa respectively. The effect of alternating pressure on the corrosion resistance of coatings in deep-sea was examined, and the surface morphology of the coating/Q345 steel interface after immersion was characterized by SEM. The results show that the failure process of the two coatings is obvious under the alternating pressure of 0.1-30 MPa. After 480 h of pressured immersion, the impedance value of the epoxy powder coating decreased by 2 and 1 orders of magnitude after 480 h immersion at 0.1-30 and 0.1-20 MPa alternating pressures, respectively, and the impedance value of the solvent-free epoxy liquid coating decreased by 3 and 2 orders of magnitude respectively after immersion in the same environment. It shows that the epoxy powder coating has better protection performance to the Q345 steel in the condition of alternating pressure, and the ability to block ion penetration is stronger. According to the LEIS results, the failure behavior of the coating gradually spreads from local sites to the whole area under the alternating pressure, and the greater the alternating pressure, the faster the spread rate of the localized damage of the coating.