Kelvin探针研究缺陷涂层的膜下腐蚀电化学行为.pdf

32 9 V o.l 32 No. 9 2010 9 Journal ofU niversity of Science and Technology Beijing Se . 2010 Kelvin 1, 2) 1, 2) 1, 2) 1, 2) 1, 2) 李迎超 高 瑾 李晓刚 董超芳 肖 葵 1) , 100083 2) , 100083 Kelvin. : , ; Kelvin, ,. Kelvin ,. , Kelvin Vmax, Vmin , ;, Kelvin Vmin , . Vmax - Vmin, 5h, , , . ; ; ; Kelvin TG 17446 Research of electrochem ical corrosion behavior under coatings w ith defects by scanning Kelvin robe 1, 2) 1, 2) 1, 2) 1, 2) 1, 2) LI Ying chao , GA O J in , L IX iaog ang , DON G Chaof ang , XIA O K u i 1) Schoolof aterialsScience and Engineering, University of Science andTechnology Beijing, Beijing 100083, China 2) BeijingKey Laboratory forCorrosion, Erosion and SurfaceTechnology, Beijing 100083, China ABSTRACT The corrosion behaviorunder coatingsw ith a pointdefectwas investigated in situ bymeans of scanningKelvin probe in both salt spray test and cyclicwetdry mi mersion test. The results showed that theKelvin potentialdistribution was identical in both the tests due to thesamedivision of coating surfaces: defect areawith thehighest potentia,l delaminated area, and intact areawith the low est potentia.l Throughmonitoring the augment ofdiameter ofKelvin potentialpeaks with tmi e, the expansion of the delam inated area was revealed. In cyclicwetdry mi mersion test, thehighestKelvin potentialVmax did not change obviouslyw ith tmi ewhile the lowest po tentialVmin increased after reaching at the valley. On the otherhand, in salt spray test, different from the rule in cyclicwetdry test, Vmin wasm inmi ized at the first stage of the test resulted from the continued diffusion of the electrolyte and the corrosive ability of slat spray particles. Based on the changing pattern ofVmax - Vmin, itwas concluded that in cyclicwetdry mi mersion te