复合涂层体系浸泡失效过程电化学阻抗谱特征

EIS Feature of Two Composite Organic Coatings on Steel During Immersion in 3.5% NaCl Solution

通过电化学阻抗技术研究了环氧防锈底漆/环氧云铁中间漆/丙烯酸聚氨酯面漆(P1)和环氧防锈底漆/氯化橡胶面漆(P2)两种复合涂层体系在60℃、3.5%Na Cl溶液中恒温浸泡失效过程,得到不同浸泡时期的电化学阻抗谱,分析了电化学阻抗谱中Bode图、涂层电阻、高频电容及特征频率的变化特征。结果表明:在浸泡初期,复合涂层体系低频阻抗值和涂层电阻下降较快,而后下降速率减缓,浸泡中期出现小幅度波动现象;高频电容和特征频率前期增大缓慢,后期增大速率加快,浸泡中期出现小幅度波动。

The failure process of two composite coatings： epoxy-antirust primer/ epoxy-MIO（micaceous iron oxide）/acrylic polyurethane（P1） and epoxy- antirust primer/ chlorinated rubber（P2） in3.5%（mass fraction） Na Cl solution at 60 ℃ was investigated by electrochemical impedance spectroscopy. The variation of EIS Bode plot, electrical resistance, high-frequency capacitors and characteristic frequency of the coatings was monitored and analyzed. Results showed that： in the early immersion period, low-frequency impedance and coating resistance decreased rapidly, but they declined slowly in the later immersion period and fluctuated in a small range in the mid-term. In addition, high-frequency capacitance and characteristic frequency increased slowly in the early immersion period and increased rapidly in the later immersion period, in the mid-term, they also fluctuated in a small range.