深海交变压力对水在环氧涂层中传输行为的影响

目的深入了解有机涂层在深海交变压力环境下的失效机制,为涂层服役寿命的预测提供指导。方法利用增重法和电化学阻抗测量技术,研究常压和深海交变压力条件下水在环氧涂层中的传输行为,计算不同环境下水的扩散系数,并分析交变压力对水在涂层中吸水动力学的影响。结果交变压力加速了水在涂层中的传输过程,使其扩散机制由常压下的理想Fick扩散行为变为非Fick扩散,延长了饱和时间,增大了涂层饱和吸水率。微观形貌观测发现,涂层内部填料/基料界面产生了大量裂痕,是导致水在涂层中扩散机制发生改变的主要原因。结论交变压力通过压力对水的推动作用及对涂层结构的破坏,加速了水在涂层中的传输。

Effect of Deep Sea Alternating Hydrostatic Pressure on Diffusion Behavior of Water through Epoxy Coating

Objective To learn the failure behavior of organic coatings under alternating hydrostatic pressure in deep sea environment and provide guidance for lifetime prediction of the coatings. Methods The diffusion behaviors of water under atmospheric pressure and deep sea alternating hydrostatic pressure were investigated by traditional gravimetric method and electrochemical (EIS). The corresponding diffusion coefficients in different environments were calculated and the effect of alternating hydrostatic pressure on the kinetics of water adsorption was also analyzed. Results Alternating hydrostatic pressure accelerated the diffusion process of water through the coatings, and the diffusion mechanism was changed from ideal Fick diffusion under atmospheric pressure to non-Fick diffusion under alternating pressure. The saturation time was prolonged and the saturated percent of water adsorption was enlarged by alternating pressure. Microscopic morphology observation showed that a large number of cracks appeared along the pigment/ binder interface inside the coatings, which was the main reason for the changes of water diffusion mechanism in the coatings. Conclusion Alternating hydrostatic pressure significantly accelerated water diffusion through the coatings by the pushing effect on water and deterioration effect on the coating structures.