DD160730A3 - WIPEABLE ALUMINUM FOIL - Google Patents

Abstract

In the invention, it is a roughenable aluminum foil, which is used as a cathode foil in electrolytic capacitors. It should be characterized by a reduced rigidity, avoid a negative effect on the effectiveness of the electrolyte and ensure a high specific surface capacity with different chemical and / or electrochemical roughening. The task is achieved by charging the aluminum to be used for producing the aluminum foil in such a way that the elements Fe; Mn; Si; An atomic percentage ratio of preferably 1: 1: 1: 500 is reached and the other accompanying elements of the pure aluminum are present in an atomic percentage of ≦ 0.1, the finished rolled cathode film being subjected to a heat treatment in a moving gas atmosphere of 723 to 743 K. Each volume element of the film roll should be at least 30 minutes, but not more than 120 minutes, above 673 K.

Description

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Title of the invention Roughenable aluminum foil

Field of application of the invention

The invention relates to a roughenable aluminum foil for use as a cathode foil in electrolytic capacitors.

Characteristic of the known technical solutions

For the production of cathode foil, it is known to use pure aluminum with a degree of Hereinfrom of Al 98 % to Al 99 »7 #. To influence the specific Flaum capacity by a chemical and / or electrochemical roughening process in acidic or neutral electrolyte manganese or copper are added to the pure aluminum in addition to already existing from the manufacturing process accompanying elements. In DE-AS 2,102,702 a cathode foil for electrolytic capacitors has already been proposed. This cathode foil is. characterized in that an aluminum-manganese alloy containing 0.2 to 2.0 % of manganese is used for its production. Furthermore, it is known (Zeitschrift Metallkunde, Vol. 70 (1979), H. 3, P. 158) that by an increase of the

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Cu content of pure aluminum to 1.5% copper and a consequent increased excretion of finest aluminum-copper precipitates, the roughening and thus the achievable surface capacity of the cathode foil can be improved.

A disadvantage of these mentioned and already known solutions is that the rigidity of the cathode foil is increased by increasing the manganese content. In order to achieve a trouble-free processability of the cathode foil in automatic winding machines for the production of capacitors with a small diameter, an additional heat treatment by means of an intermediate annealing process is required.

When increasing the copper content, the electrolyte used in the chemical and / or electrochemical roughening is rapidly changed in its effectiveness, so that an ongoing renewal or regeneration of the electrolyte is necessary. The fluctuating copper content in the electrolyte particularly strongly adversely affects the maintenance of uniform etching conditions,

Another shortcoming is finally the fact that widely differing specific I ¹ Iächenkapazitäten be achieved with the known aluminum foils in the roughening according to the use of an acidic or neutral electrolyte, whereby each film of limited use in accordance with its manufacturing process.

Object of the invention

Bas goal of the invention is to develop an aluminum foil, by means of which Katodenfolie high quality, without additional expenditure by an interposed heat treatment, can be manufactured.

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Presentation of the essence of the invention

The technical object of the invention to be solved is to produce an aluminum foil for electrolytic capacitors, by means of which an increase in the rigidity that leads to winding machines to disturbances, and a negative effect on the effectiveness of the electrolyte avoided and the production of a highly roughened cathode foil with high specific area capacity ensures different chemical and / or electrochemical roughening.

According to the invention this is achieved in that the aluminum to be used for the production of the aluminum foil is charged so that for the elements Pe; Mn; Si; Al is an atomic percent ratio of 1: 1: 1: 600 to 1: 1: 1: 400, preferably 1: 1: 1: 500, is reached and the other accompanying elements of pure aluminum in an atomic percentage of = 0.1, the finished rolled Cathode film is subjected to such a heat treatment in a moving gas atmosphere of 723 to 743 K, that each volume element of the film roll is above 673 K for at least 30 minutes, but not more than 120 minutes.

embodiment

The invention will be explained in more detail by way of example.

1.6 t of pure aluminum Al 99.6 are used in a melting furnace and an analysis of the melt is carried out.

For example, in a chemical analysis of 0.18 % Fe obtained; 0.12% Si; 0.002 # Ou; 0.01 % Mg;

0.01% Mn; 0.01 # Ti and 0.01 % Zn are 38.6 kg of an AlFe master alloy containing 10.2 1 of Fe; 0.12% Si; 0.003 ° C ; 0.01% Mn;

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0.01 # MgJ 0.01 $> Ti; 0.01% Zn and 41.0 kg of an AlMn master alloy with

16.2% Mn; 0.13% Si? 0.20 % Fe; 0.01 % Mg; 0.005 % Cu? 0.01 io of Ti; 0.01% Zn and 11.7 kg of an AlSi master alloy with

12.4 % Si; 0.20 % Pe; 0.005 % Cu; 0.01 % Mg; 0.01 % Mn; 0.01% Ti; 0.01% Zn! Added ·

After melting the master alloys and intensive mixing of the material in the furnace, the melt is freed from oxidic admixtures and gas by known methods and a billet is produced by continuous casting, followed by hot rolling to a thickness of 8 mm and cold rolling in a known manner to a thickness of, for example, 0.5 mm.

After recrystallization annealing for 12 hours at 773 K, the strip is cold rolled again to a thickness of 0.05 mm. After cutting the film into rolls of, for example, 500 mm wide and 350 mm in diameter, the rolls must be in an annealing oven an air circulation of 2 m / s at an air temperature of 723 K for 3 hours. After the cooling has taken place outside the annealing furnace, the aluminum foil produced in this way can be inserted and roughened in the chemical and / or electrochemical etching bath for cathode foil.

The advantages of the aluminum foil produced according to the invention are that it can be used in electrolytic capacitors without a necessary after the etching process heat treatment / G lühung for series with smallest winding diameter that with her both in acidic and neutral electrolytes with chemical and electrochemical etching high roughening can be achieved and a uniform effectiveness of

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Electrolytes is retained over a longer period by eliminating the accumulation of interfering chemical alloying elements.

Claims (3)

231288 6 Invention proposal Aluminum foil for the production of cathode foil for electrolytic capacitors, consisting of aluminum with a purity of 99-6 # and other metallic impurities, characterized in that the elements Pe; Mn? Si; Al in an atomic percent ratio of 1: 1: 1: 600 "to 1: 1: 1: and the other accompanying elements of pure aluminum in an atomic percentage of = 0.1 and the finished rolled cathode foil a heat treatment in" moving gas atmosphere 723-743 K. is subjected. 2 · Aluminum foil according to item 1, characterized in that the atomic percentage of Fe; Mn; Si? Al is preferably 1: 1: 1: 500. 3. aluminum foil according to item 1 and 2, characterized in that each Yolumenelernent the film roll is at least 30 minutes, but not more than 120 minutes, about 673 K.