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首页> 外文期刊>International Journal of Electrochemical Science >The effect of various cyclic Wet-Dry exposure cycles on the Failure Process of Organic Coatings
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The effect of various cyclic Wet-Dry exposure cycles on the Failure Process of Organic Coatings

机译：各种循环的干湿循环暴露对有机涂料破坏过程的影响

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The effect of various dry-wet cycles on the failure processes of the acrylic polyurethane heat-reflectiontopcoat and thick epoxy anti-rust primer was investigated, where simulated seawater constituted the wetcondition and air constituted the dry environment. Electrochemical impedance spectroscopy (EIS),Fourier Transform infrared spectroscopy (FT IR) and Scanning electron microscopy (SEM) were usedto characterize the coatings after exposure under the cyclic wet-dry conditions. The results hereinindicate that the primary cause of coating degradations was the reaction of functional groups in coatingswith the NaCl solution (the simulated seawater). Furthermore, alternate wetting and drying can promotethe incidence of fillers falling off the coatings, and thus, increasing the micro-pores in the coatings. Thispore-creating effect can multiply the number of defects in the coating and accelerate the degradation ofthe coatings. However, the degradation rate of the coatings is evidently influenced by the wet-dry cycle.Under conditions of the same total test times, increased length of the per-cycle wetting times acceleratesthe coating degradation even though the total wetting times may be equal. If the wetting time in one wet-dry cycle is shorter, the water absorption of the coating is lesser. During the following drying process,the absorbed water within the coating may be completely evaporated, and the hydrolysis of the coatingcan weaken. If the wetting time per cycle is long enough, the absorbing water does not fully evaporatefrom the coating during the following drying period. This can accelerate degradation of the coating.Moreover, oxygen accelerates the reaction on the cathode during the drying period in one cycle, leadingto a relatively quick corrosion of metal matrix and a decrease of adhesive force of the coating.
机译：研究了不同的干湿循环对丙烯酸聚氨酯热反射面漆和厚环氧防锈底漆的破坏过程的影响，其中模拟海水构成潮湿条件，空气构成干燥环境。电化学阻抗谱（EIS），傅立叶变换红外光谱（FT IR）和扫描电子显微镜（SEM）用于表征在循环湿干条件下曝光后的涂层。结果表明，涂​​层降解的主要原因是涂层中的官能团与NaCl溶液（模拟海水）的反应。此外，交替的润湿和干燥可以促进填充剂从涂层上掉落的发生，因此增加了涂层中的微孔。这种产生孔的作用可以使涂层中的缺陷数量增加，并加速涂层的降解。然而，涂层的降解率显然受湿-干循环的影响。在相同的总测试时间的条件下，即使总润湿时间相等，每次循环润湿时间长度的增加也会加速涂层的降解。如果在一个干湿循环中的润湿时间较短，则涂层的吸水率会降低。在随后的干燥过程中，涂层内吸收的水分可能会完全蒸发，涂层的水解作用会减弱。如果每个周期的润湿时间足够长，则在接下来的干燥期间吸收水不会从涂层中完全蒸发。这可以加速涂层的降解。此外，氧气在一个周期的干燥周期中加速了阴极上的反应，从而导致金属基体的腐蚀相对较快并且涂层的粘附力降低。

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