Huiping BAI
,
Fuhui WANG
材料科学技术（英文）
The electrochemical behaviors of high temperature oxide film formed on the sputtered microcrystalline coating of M38 alloy (mc-M38) were investigated by potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques in 3.5% NaCl solution. Mott-Schottky analysis was used to study the semi-conductive properties of the surface oxide. The results of the capacitance measurements showed that the oxide films on both the coating and the cast alloy were p-type semiconducting characteristics. Both the carrier density (Na) and the flat band potential (Efb) were obviously frequency-dependent, and the optimal frequency range was from 1000 to 1500 Hz. The oxidized coating exhibited higher protectivity than the oxidized cast alloy due to the lower carrier density compared with that of the oxidized cast alloy. The EIS data of the long-term immersing tests suggested that the oxide film served as an inner-barrier layer against chloride ions. The penetration of the aggressive ions into the surface oxide resulted in the decreased polarization resistance as a function of the immersion time.
关键词:
High temperature oxide film
,
temperature
,
oxide
,
film
,
Protective
,
p
钮晓博
,
王毅
,
钟庆东
,
王超
,
盛敏奇
,
周琼宇
腐蚀学报（英文）
用电位-电容测试和Mott-Schottky分析技术研究碳钢/环氧涂层在 5%H2SO4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%H2SO4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.
关键词:
Mott-Schottky分析
,
semiconductor
,
epoxy coating/carbon steel
,
dipole polarization
朱振宇
,
王毅
,
钟庆东
,
吴红艳
,
杜海龙
,
盛敏奇
,
周琼宇
腐蚀与防护
采用电化学方法以及Mott-schottky理论,研究了两种不同晶粒大小的铜在不同Cl-浓度溶液中的钝化膜形成过程和机理,计算了不同Cl-浓度溶液中铜在0.2V、0.4V两种电位下阳极氧化后钝化膜中的载流子密度。结果表明：铜在不同条件下表面氧化膜的Mott-schottky曲线线性斜率为负,呈现P型半导体的性质,膜中的多数载流子为空穴。随着铜晶粒度的增大和阳极钝化电位的升高,铜表面钝化膜中的受主密度NA降低;随着介质溶液中的Cl-浓度的升高,钝化膜中的受主密度NA不断增大。
关键词:
Cu
,
晶粒度
,
Cl-
,
钝化膜
,
Mott-Schottky分析
