论文部分内容阅读
用电位-电容测试和Mott-Schottky分析技术研究碳钢/环氧涂层在5%H_2SO_4溶液中腐蚀失效过程的极化及半导体行为.结果表明:碳钢/环氧涂层在5%H_2SO_4溶液中浸泡10 min时形成了一个金属-绝缘体-半导体(MIS)结构,随着浸泡时间的延长,涂层逐渐表现出半导体的性质.碳钢/环氧涂层在浸泡1 d时,涂层表现为n型半导体,Nyquist图在整个频率域内其交流阻抗出现两个半圆弧,说明此时的金属/涂层电极存在两个时间常数.碳钢/环氧涂层在浸泡3 h到5 d时,在电场作用下发生偶极极化,偶极电场阻碍了涂层中载流子的迁移,起到减缓腐蚀的作用.偶极弛豫效应使碳钢/环氧涂层电极的电容随电位绝对值的增大而减小,并且造成了其频率的依赖性.碳钢/环氧涂层在浸泡7 d以上时,碳钢与涂层形成金属-半导体接触,随着浸泡时间延长,载流子密度逐渐增加.
The polarization and semiconducting behavior of carbon steel / epoxy coating in 5% H 2 SO 4 solution were investigated by potentiometric-capacitance test and Mott-Schottky analysis.The results showed that the corrosion resistance of carbon steel / epoxy coating in 5% H 2 SO 4 (MIS) structure was formed when immersed in solution for 10 min, and the coating gradually showed the semiconducting properties with the immersion time.Carbon steel / epoxy coating immersed for 1 d, the coating The performance of the n-type semiconductor, Nyquist diagram in the entire frequency domain of the two half-arc AC impedance, indicating that the metal / coating electrode at this time there are two time constants. Carbon steel / epoxy coating immersed in 3 h to 5 d, dipole polarization occurs under the action of electric field, and the dipole field impedes the carrier migration in the coating and plays the role of slowing the corrosion.The dipolar relaxation effect makes the capacitance of the carbon steel / epoxy coated electrode With the absolute value of the potential decreases and causes its frequency dependence Carbon steel / epoxy coating When immersed for more than 7 days, the carbon steel and the coating form a metal-semiconductor contact, with the soaking time , Carrier density gradually increased.