电化学阻抗谱法研究环氧膜的渗水机理

Electrochemical Impedance Studies of the Mechanism of the Penetration of Water in an Epoxy Resin Film

本工作测量了覆盖环氧膜的铝电极在NaCl溶液中的电化学阻抗谱,并求得了该膜的膜电阻、膜电容和环氧膜与底金属间的腐蚀电阻及双电层电容.由膜电容求得该膜的介电常数为5.2.此种膜未浸入NaCl溶液前的介电常数为4.9将上述数据与未覆盖环氧膜的铝电极的电化学阻抗数据比较,可认为溶液是经上述膜中的化学通道而渗入膜内的.

Electrochemical impedance spectra were measured for the aluminum electrodes coated and uncoated with an epoxy cresol novolac film in 0.5mol· dm-3NaCl solution (60℃) at open circuit petential, respectively. By fitting the Nyquist curves thus obtained with the equivalent circuit generally used for coated electrode, the values of the film resistance, the film capacitance, the electrochemical reaction resistance and the double layer capacitance at metal / coating interface obtained were used to estimate the mechanism of the penetration of water into the film which is demonstrated to be conducted by chemical channels. After the film has been in the said solution for 8h, its dielectric constant is 5.2 calculated from the film capacitance, which is found to be close to that of the dry film determined using a Q meter.