Abstract: The corrosion structure, grain size and boundary distribution of aluminum anode foil for low voltage electrolytic capacitor were analyzed and investigated based on observation of scanning electronic microscope and orientation mapping with electron back scattering diffraction technology. It is indicated that large corrosion holes or channels will appear frequently along the grain boundaries, especially along the high angle grain boundaries, which lead to the inhomogeneity of corrosion structure and reduction of specific capacity. The higher defect density and corresponding local concentration of corrosion current density around grain boundaries induce the preferred corrosion of the boundaries. Increasing the boundary density can reduce the segregation of impurity atoms and the distribution inhomogeneity of current density. Therefore, it is possible to increase the specific capacity by means of reducing the grain size under some electrochemistry corrosion conditions.
Influence of grain boundaries on corrosion structure of low voltage aluminum foil
Abstract:
The corrosion structure, grain size and boundary distribution of aluminum anode foil for low voltage electrolytic capacitor were analyzed and investigated based on observation of scanning electronic microscope and orientation mapping with electron back scattering diffraction technology. It is indicated that large corrosion holes or channels will appear frequently along the grain boundaries, especially along the high angle grain boundaries, which lead to the inhomogeneity of corrosion structure and reduction of specific capacity. The higher defect density and corresponding local concentration of corrosion current density around grain boundaries induce the preferred corrosion of the boundaries. Increasing the boundary density can reduce the segregation of impurity atoms and the distribution inhomogeneity of current density. Therefore, it is possible to increase the specific capacity by means of reducing the grain size under some electrochemistry corrosion conditions.
图1 低压电解电容器铝箔晶界的 化学腐蚀结构和晶界取向差分布 Fig.1 Chemical corrosion microstructure and misorientation distribution of grain boundaries in aluminum foils for low voltage electrolytic capacitor (thick lines: more than 15°; thin lines: less than 15°) (a)—Microstructure after hydrochloric acid corrosion; (b)—Distribution of high and low angle boundaries