温度与循环热冲击对聚酰亚胺涂层耐蚀性影响

摘要

Objective To study the corrosion resistance and thermal shock resistance performance of polyimide coating on N80 steel. Methods A polyimide anticorrosive coating was obtained on the surface of N80 steel by electrostatic powder spray-ing technique. The corrosion resistance of PI coating was evaluated by immersion test in different corrosive media at different temperature. The thermal shock resistance of PI coating was studied by cyclic thermal shock test. The surface morphology of PI coating was observed by scanning electron microscopy (SEM). Results TGA showed that the thermal decomposition tempera-ture (Td5) of the PI coating was 518 ℃. The results of electrochemical impedance spectroscopy and SEM observations showed that the higher the corrosion medium temperature was, the faster the corrosion resistance decreased. The corrosion resistance of the coating in 3.5% NaCl solution was better than that in 25% HCl solution. After cyclic thermal shock at different temperatures, the coating surface was intact. Conclusion Polyimide coating has excellent thermal shock resistance. Temperature and electro-lyte have a significant impact on the corrosion resistance of PI coating.%目的 研究聚酰亚胺涂层对N80钢的防腐性能和耐热冲击性能.方法 采用静电粉末喷涂在N80钢表面获得一种聚酰亚胺防腐涂层,通过高温浸泡实验评价涂层在不同温度下、不同腐蚀介质中的耐蚀性能,通过循环热冲击实验评价涂层的耐热冲击性能,通过扫描电子显微镜(SEM)观察实验前后涂层的表面微观形貌.结果 热重分析(TGA)表明,聚酰亚胺涂层的热分解温度(td5)为518 ℃.电化学交流阻抗测试结果和SEM形貌观测表明,腐蚀介质温度越高,耐蚀性能下降越快,涂层在3.5%NaCl溶液的耐蚀性能比在25%HCl溶液中更好.涂层在经过不同温度的循环热冲击之后,表面无破损.结论 聚酰亚胺涂层具有优异的耐热冲击性能,温度和腐蚀介质对涂层的耐蚀性能有重要影响.