Abstract:

The failure process of fluorocarbon coating in 3.5% NaCl solution under wet-dry cyclic condition was studied with electrochemical impedance technique，Fourier transform infrared spectrometry(FTIR)and scanning electronic microscope(SEM).The results showed that the failure rate of coating under wet-dry environment was faster than that under complete immersion condition. The wet-dry condition promoted formation of micro-pores in the coating and resulted in decreased coating resistance and increased water absorption. The failure mechanism for fluorocarbon coating under wet-dry environment was suggested. The coating volume experienced swelling and contraction during the wet-dry cycle，which resulted in increased micro-pores and cracks in the coating. Electrolyte entered the coating defects under the action of osmotic pressure，leading to blisters and reduced adhesion of the coating to the substrate.

Key words: 氟碳涂层, 干湿交替, 失效

摘要：

用电化学交流阻抗（EIS）、红外光谱（FTIR）和扫描电镜（SEM）等手段研究了氟碳涂层在干湿交替及全浸泡环境下的失效过程。结果表明，干湿交替环境下氟碳涂层的失效速率快于全浸泡环境下的失效速率，干湿交替环境使得涂层孔隙率增大，涂层的电阻降低，电容增大，加速了电解质溶液在涂层中的渗透；氟碳涂层在干湿交替环境下的失效原因，主要是由于干湿交替循环使涂层经历增大和缩小的往复变化，使得涂层内部孔隙增大，局部产生微裂纹且涂层与基体附着力降低，最终导致涂层起泡及失效。

关键词: 氟碳涂层, 干湿交替, 失效