摘要
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.
In this paper,the corrosion degradation process and semiconducting character of epoxy coating/carbon steel were examined in 5%H_2SO_4 solution by used of potential-capacitance measurement and Mott-Schottky analysis techniques.A film with MIS structure may formed on the surface of epoxy coating/carbon steel immersed in 5%H_2SO_4 for 10 min,with the extension of soaking time,the system gradually showed a semiconductor-like nature.When epoxy coating/carbon steel immersed for 1 d,the system exhibited n-type semiconducting,its Nyquist frequency map had two semi-impedance arcs in the whole frequency region,which showed that the epoxy coating/carbon steel electrode had two time constants.The epoxy coating/carbon steel immersed in 5%H_2SO_4 for 3 h～5 d,the dipole polarization had occurred under the electric field, electric dipole might hinder the migration of carriers,and slowed down the corrosion.Dipole relaxation effect made the capacitor of epoxy coating/carbon steel reduced with the absolute value of potential increased,and resulted in dependence on its frequency.The epoxy coating/carbon steel immersed in 5%H_2SO_4 for more than 7 d,the carbon and coating formed metal-semiconductor contacts,with the extension of soaking time,the carrier density increased gradually.
出处
《腐蚀科学与防护技术》
CAS
CSCD
北大核心
2010年第6期499-503,共5页
Corrosion Science and Protection Technology
基金
国家自然科学基金项目(50571059
50615024)
教育部新世纪优秀人才支持计划资助项目(NCET-07-0536)和教育部创新团队计划项目(IRT0739)资助
