| 摘要 |
PROBLEM TO BE SOLVED: To provide aluminum foil from which hard foil for an electrolytic capacitor cathode having high capacitance is obtained. SOLUTION: The alumimum foil has Al purity of >=99.8 wt.%. In the aluminum foil, the amount of crystallized and precipitated products with a grain size of 1.0 to <5.0μm is 50 to 400 ppm expressed in terms of Fe concentration. Further, the amount of crystallized and precipitated products with a grain size of 0.1 to <1.0μm is 3 to 35 ppm expressed in terms of Fe concentration. The aluminum foil can be obtained by various methods. As one method, an ingot of which the content of Fe is 0.02 to 0.06 wt.%, and the purity of Al is >=99.8 wt.% is prepared. This ingot is subjected to homogeneous treatment under the temperature condition of >=500 deg.C for 0.5 to 3 hr. After that, the ingot is subjected to hot rolling and cold rolling at a rolling ratio of >=95% to obtain the aluminum hard foil for an electrolytic capacitor cathode. Further, the aluminum hard foil for an electrolytic capacitor cathode can be obtained also by other methods.
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