海水管路黄铜焊接接头在人工海水中的电化学阻抗谱

利用扫描电镜(SEM)、阳极极化与电化学阻抗谱(EIS)试验方法,研究了紫铜管路中的黄铜焊缝在人工海水中的腐蚀特性。结果表明,在Tafel区,黄铜焊缝以CuCl2-络合离子和Zn2 溶解,并且CuCl2-和Zn2 的扩散是该溶解过程的控制步骤;当电极电位极化到-0.01～ 0.31V时,难溶物Cu2O、CuCl、ZnO和Zn(OH)2ZnCl2附着在电极表面阻碍电极极化,因而在EIS谱图上出现2个容抗弧;电极电位超过 0.31V后,难溶物开始溶解至 0.57V完全溶解,这时电极反应以脱锌腐蚀为主,电极过程为Zn2 离子向溶液扩散控制。

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF WELDED JOINTS OF COPPER PIPE IN ARTIFICIAL SEAWATER

The corrosion behavior of welded joints of copper pipe in artificial seawater was studied by anodic polarization,electrochemical impedance spectroscopy(EIS)and scanning electron microscopy(SEM).The brass welded joint was dissolved into Zn2 and CuCl-2,and this process was controlled by the diffusion of Zn2 and CuCl-2,in the Tafel region.In the anodic region between-0.01 V and 0.31 V(SCE),the anode was covered with Cu2O,CuCl,ZnO and Zn(OH)2ZnCl2 films which hindered electrochemical polarization.Two arcs of capacitive reactance appeared in the EIS.In the region between 0.31 V and 0.57 V(SCE),the dezincification reaction was dominant process which was controlled by the diffusion of Zn2 .