Investigation of Formation Process of the Chrome-free Passivation Film of Electrodeposited Zinc
The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface morphologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron microscopy (SEM) and determined by energy dispersion spectrometry (EDS), respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy (XPS) show the chrome-free passivation film composed of ZnO, SiO2,TiO2, Zn4Si2O7(OH)2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.
作 者： ZHU Li-qun YANG Fei HUANG Hui-jie 作者单位： School of Materials Science and Engineering, Beijing University of Aeronautics and4stronautics, Beijing, 100083, China 刊 名： 中国航空学报(英文版) ISTIC 英文刊名： CHINESE JOURNAL OF AERONAUTICS 年，卷(期)： 2007 20(2) 分类号： V2 关键词： electrodeposited zinc chrome-free pasivation film film formation process