荧光剂对铝合金防护涂层腐蚀监测敏感性的影响

Effects of Fluorescent Agent on Sensitivity of Corrosion Monitoring of Anticorrosion Coatings on Aluminum Alloy

荧光剂是监测铝合金早期腐蚀常用的一种技术。文中研究了荧光剂的种类和浓度对铝合金防护涂层腐蚀监测敏感性的影响。通过荧光光谱研究了8-羟基喹啉、桑色素和香豆素3种荧光剂对Al3+和pH的荧光响应;通过红外光谱、扫描电镜、荧光显微镜和电化学阻抗谱研究了荧光剂添加对膜层完整性、耐蚀性及腐蚀监测敏感性的影响。结果表明:8-羟基喹啉对Al3+浓度变化有明显的荧光响应,香豆素对pH的变化有明显的荧光响应。8-羟基喹啉和香豆素的添加对溶胶液和溶胶凝胶膜层未产生明显影响,添加荧光剂的溶胶液保持稳定,膜层致密且与基体结合强度高。荧光剂的添加增强了膜层的防护性能,8-羟基喹啉对金属腐蚀表现出缓蚀作用。8-羟基喹啉和香豆素都可以监测腐蚀,在含有8-羟基喹啉的膜层中最早监测到的荧光点尺寸更小,约20μm,因此8-羟基喹啉表现出更高的腐蚀监测敏感性。

Fluorescent agent can be used to monitor the initial stage of aluminum alloy corrosion. Effects of species and concentration of fluorescent agents in protective coatings of aluminum alloy on the corrosion monitoring sensitivity were studied. Fluorescence responses of 8-hydroxyquinoline, morin and coumarin to Al3＋ and pH were studied by fluorescence spectra. The influence of fluorescent agent addition on the corrosion monitoring sensitivity and performance of the coatings was characterized by fourier transform infrared spectroscopy （FTIR）, SEM, fluorescence microscope and electrochemical impedance spectroscopy （EIS）. Results show that 8-hydroxyquinoline has obvious fluorescence response to the change of Al3＋ concentration. Coumarin is sensitive to the change of pH values. The addition of 8-hydroxyquinoline or coumarin does not obviously affect the sol solutions and sol-gel films. Additionally, the sol solutions keep stable, and the films are dense with good adhesion to the matrix. The addition of fluorescent agent enhances the protection properties of the films, and 8-hydroxyquinoline shows the corrosion inhibition performance. Both 8-hydroxyquinoline and coumarin can be used to monitor corrosion. The size of fluorescent spot detected in the film with 8-hydroxyquinoline, is about 20 μm, smaller than that in the film with coumarin, which indicates the higher sensitivity of 8-hydroxyquinoline to monitor corrosion.