纳米TiO_2对丙烯酸酯聚氨酯涂层/碳钢界面的初期失效行为的影响

Effect of nano-TiO_2 on the initial corrosion behavior of the acrylic polyurethane coating/carbon steel interface in NaCl solutions

采用激光电子散斑干涉技术、电化学阻抗技术和扫描电化学显微镜技术实时、动态和原位观测了涂覆丙烯酸聚氨酯涂层的碳钢在质量分数为3.5%的Na Cl溶液中浸泡初期的界面腐蚀行为,并对比了纳米Ti O2的添加对界面腐蚀行为的影响.在浸泡初期无宏观缺陷存在时,激光电子散斑干涉技术成功检测到涂层界面的微小变化,电化学阻抗技术显示不同涂层低频阻抗膜值的变化情况,均与扫描电化学显微镜技术获得的腐蚀电化学形貌结果一致,即在浸泡初期,未添加纳米Ti O2的涂层其界面变化速度(即锈蚀萌生速度)较添加涂层明显得多,表明纳米Ti O2可延缓涂层/碳钢的界面失效.

The initial corrosion behavior of the acrylic polyurethane coating / carbon steel interface in a 3. 5% NaCl solution was in-situ investigated by electronic speckle pattern interferometry（ ESPI）,electrochemical impedance spectroscopy（ EIS） and scanning electrochemical microscopy（ SECM）. The effect of nano-TiO2 on the interfacial behavior was examined. At the beginning stage without macroscopic defects,a tiny change at the interface was successfully detected by ESPI. EIS results could reflect the change of low frequency impendence moduli,which were agreed with the electrochemical morphology obtained by SECM. In other words,the interfacial changing velocity（ corrosion initiation rate） of the coating without nano-TiO2 is faster than that of the coating with nano-TiO2,indicating that the addition of nano-TiO2 slows down the corrosion of the acrylic-based polyurethane / carbon steel interface.