JPS6321740B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to an aluminum alloy foil for an electrolytic capacitor cathode. In this specification, "%" refers to "% by weight". Conventional technology and its problems In order to improve the performance of electrolytic capacitors,
It is necessary to increase not only the capacitance of the anode foil but also the capacitance of the cathode foil. In order to increase the capacitance of foil, it is effective to increase the surface area by etching the foil and forming minute depressions on the surface of the foil at a high density. In this case, the corrosion loss becomes excessive, and as a result, the capacitance of the foil decreases. Furthermore, in order to reduce the size and weight of capacitors, it is necessary to reduce the thickness of the foil, and to achieve this, the strength of the foil must be increased. Therefore, the aluminum alloy foil for an electrolytic capacitor cathode must have a large capacitance, no excessive corrosion loss during etching, and a high mechanical strength. Although various aluminum alloy foils for electrolytic capacitor cathodes have conventionally existed, the reality is that there has been no foil that satisfies all of the above three conditions. An object of the present invention is to provide an aluminum alloy foil for an electrolytic capacitor cathode that can satisfy all of the above conditions. Means for Solving the Problems One aluminum alloy foil for an electrolytic capacitor cathode of the present invention is a continuously cast aluminum alloy foil containing 0.2 to 1.0% silicon and 0.2 to 2.0% manganese, with the balance being aluminum and inevitable impurities. Another aluminum alloy foil for an electrolytic capacitor cathode according to the present invention contains 0.2 to 1.0% silicon and 0.2 to 2.0% manganese.
Contains 0.1-1.0% copper and vanadium
It is formed from a continuously cast aluminum alloy plate containing at least one of 0.003 to 0.3%, with the remainder being aluminum and unavoidable impurities. Silicon and manganese have the property of increasing the capacitance of aluminum alloy foil when they are both contained in aluminum, but if the silicon content is less than 0.2% and the manganese content is less than 0.2%, the foil The effect of increasing the capacitance cannot be obtained, and the silicon content exceeds 1.0%,
If the manganese content exceeds 2.0%, a fine etched structure cannot be obtained, the capacitance of the foil becomes small, and furthermore, the loss of corrosion becomes excessive. Therefore, the silicon content should be selected within the range of 0.2 to 1.0%, and the manganese content should be selected within the range of 0.2 to 2.0%. The reason why the capacitance of aluminum alloy foil increases by containing both silicon and manganese is as follows. In other words, as is well known, the capacitance of aluminum alloy foil is proportional to the surface area of the foil, but in order to increase the surface area of the foil,
It is necessary to perform etching to uniformly and densely form fine recesses on the surface of the foil. When both silicon and manganese are contained in aluminum, it is possible to obtain a structure in which a large number of fine Al--Si--Mn compounds are dispersed in the aluminum matrix. Since the Al--Si--Mn compound is potentially noble and has a large electrode potential difference with the aluminum matrix, the aluminum matrix is preferentially corroded during etching.
Fine depressions are uniformly and densely formed on the surface of the foil,
The surface area of the foil increases. However, the silicon content exceeds 1.0% and the manganese content exceeds 2.0%.
If it exceeds this, the Al--Si--Mn compound becomes coarse and a fine etched structure cannot be obtained, resulting in a decrease in capacitance. In addition, for continuously cast aluminum alloy sheets containing both silicon and manganese, the above
Since the Al--Si--Mn compound becomes finer and more uniformly dispersed, when etching is applied to aluminum alloy foil formed by rolling from this continuously cast aluminum alloy sheet, extremely fine recesses are created on the surface of the foil. The capacitance increasing effect of aluminum alloy foil is further improved by adding both silicon and manganese, which are generated at high density and described above. In the above, when at least one of copper and vanadium is contained in aluminum together with silicon and manganese, the solid solubility limit of silicon and manganese is lowered and more Al-Si-Mn compounds are precipitated. At the same time, it can dissolve itself in solid solution in the aluminum matrix, improve the etching properties of the matrix, and enhance the effects of containing silicon and manganese as described above. However, if the copper content is less than 0.1% and the vanadium content is less than 0.003%, the above effects cannot be obtained, and if the copper content exceeds 1.0% and the vanadium content exceeds 0.3%, Etching becomes excessive and the capacitance decreases. Therefore, the copper content should be selected within the range of 0.1 to 1.0%, and the vanadium content should be selected within the range of 0.003 to 0.3%. In a continuously cast aluminum alloy sheet, the elements contained in the aluminum are supersaturated in solid solution in the aluminum, and the crystallized products are fine and uniform, so the strength is high. Therefore, the strength of the foil formed by rolling from such a continuously cast plate naturally increases. Furthermore, the aluminum alloy foil according to the present invention may contain impurities such as iron that are inevitable during manufacturing. Among impurities, the iron content is particularly
If it exceeds 0.5%, coarse Al―Si―Mn―
Since Fe compounds may crystallize and inhibit the effects of the aluminum alloy foil according to the present invention, the content of iron among impurities is preferably 0.5% or less. Continuously cast aluminum alloy sheets are obtained by continuous casting and rolling methods such as the 3C method and the Hunter method without going through the usual hot rolling process. The continuously cast aluminum alloy plate is formed to have a thickness of, for example, 25 mm or less. Then, a foil is formed from such a continuously cast aluminum alloy plate through cold rolling and foil rolling. Continuously cast aluminum alloy sheets are sometimes subjected to intermediate annealing before being made into foil. Examples Examples of the present invention will be described below along with comparative examples. Continuously cast plates having a thickness of 25 mm or less were manufactured from alloys A to C and E of the five types of aluminum alloys having the compositions shown in Table 1 by a continuous casting and rolling method at a cooling rate of 1 m/min. These continuously cast plates were then subjected to cold rolling and foil rolling to form two aluminum alloy foils.
Further, a slab was cast from Alloy D by a semi-continuous casting method (cooling rate 0.05 m/min), and two sheets of alloy foil were formed from this slab by a normal foil manufacturing method. Thereafter, the strength of each of the various alloy foils was measured using one of each foil. In addition, another piece of alloy foil was immersed in an aqueous solution of 3% hydrochloric acid and 0.5% oxalic acid at a temperature of 60°C, and etched with alternating current at a current density of 30 A/dm ² for 1 minute and 30 seconds. Capacity was measured.

[Table] The results of the above examples and comparative examples are summarized in Table 2.

[Table] As is clear from Table 2, Alloys A to C have higher capacitance and strength than Alloys D and E. Effects of the Invention One aluminum alloy foil for an electrolytic capacitor cathode of the present invention is formed from a continuously cast aluminum alloy sheet containing 0.2 to 1.0% silicon and 0.2 to 2.0% manganese, with the balance being aluminum and inevitable impurities. Therefore, fine Al
- A structure in which a large number of Si-Mn compounds are dispersed in an aluminum matrix can be obtained. Al
- Since the Si--Mn compound is potentially noble and has a large electrode potential difference with the aluminum matrix, the aluminum matrix is preferentially corroded during etching, resulting in uniform and fine depressions on the surface of the foil. Occurs in high density. Therefore,
Capacitance increases. Furthermore, the mechanical strength also increases. Another aluminum alloy foil for an electrolytic capacitor cathode of the present invention has a silicon content of 0.2
~1.0% and manganese 0.2-2.0%, and further contains at least one of copper 0.1-1.0% and vanadium 0.003-0.3%, with the balance being aluminum and inevitable impurities. Therefore, copper and/or vanadium lower the solid solubility limits of silicon and manganese, causing more Al-Si-Mn compounds to precipitate, and also to precipitate more Al--Si--Mn compounds in the aluminum matrix. It dissolves in solid solution and improves the etching properties of the matrix. Therefore, the capacitance and strength are greater.

Claims (1)

[Claims] 1. 0.2-1.0% silicon and 0.2-2.0% manganese
1. An aluminum alloy foil for an electrolytic capacitor cathode, which is formed from an aluminum alloy continuous cast plate containing aluminum and unavoidable impurities. 2 Silicon 0.2-1.0% and manganese 0.2-2.0%
Contains 0.1-1.0% copper and vanadium
An aluminum alloy foil for an electrolytic capacitor cathode, which is formed from an aluminum alloy continuous casting sheet containing at least one of 0.003 to 0.3%, with the balance being aluminum and inevitable impurities.