| 摘要 |
PURPOSE: To provide a method for producing aluminum foil for high voltage of an aluminum foil having etch pits of high density and capable of remarkably increasing capacitance by improving its electrolytic etching properties. CONSTITUTION: The slab of pure aluminum having >=99.90wt.%. purity is subjected to homogenizing treatment at 450 to 620 deg.C for 1 to 20hr and is successively subjected to hot rolling and cold rolling. After that, it is heated at 180 to 260 deg.C for 1 to 20hr, is subjected to process annealing treatment and is next subjected to final cold rolling at 5 to 25% draft. Then, the obtd. aluminum foil is immersed in pure water of 75 to 95 deg.C having <=10μS electric conductivity for 30 to 250sec to form a hydroxide film, which is furthermore heated at 480 to 620 deg.C for 1 to 5hr and is subjected to final annealing. On the surface of the obtd. aluminum foil,γ-Al2 O3 crystals are present by 25 to 1000 pieces/mm<2> . Furthermore, by its immersion into the same pure water, the hydroxide film of 0.010 to 0.200g/m<2> is formed on the surface.
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