DE2255309A1 - PROCESS FOR THE PRODUCTION OF ALUMINUM ELECTRODES FOR ELECTROLYTE CAPACITORS - Google Patents

Description

ALUMINUM ROLLING MILL ?: SINGEN GMBH , Singen / Htwl. Process "for the production of aluminum electrodes ..

V.

for electrolytic condensers. :

The electrodes of an electrolytic capacitor generally exist made of roughened i.e. etched aluminum strips. The roughening of the tape increases the Surface and thus an increase in capacity or with "given Capacity a reduction in the size of the electrodes achieved.

Pure aluminum is usually used as the starting material for the production of etched anode strips and pure aluminum or aluminum alloys containing manganese are used for the production of etched cathode strips. These materials are cast into bars with a rectangular cross-section using the known continuous and permanent mold casting processes. The ingots are generally heated to a V / armumf.orm temperature between 400 and 550 C and hot rolled on hot rolling stands to a plate thickness of 2-10 mm. The plates are cold rolled in several passes to their final thickness to the strip and used for etching in this condition or in an additionally heat-treated condition.

BATH ORIGINAL 409821/0544

The etched strips produced in this way today often no longer meet the requirement for a sufficiently high roughening, which dissuades the prerequisite for the construction of a volumenm ^ 'ps-ig small electrolytic capacitor. It was therefore necessary to find a method according to which even higher roughening than are possible with the previously known methods.

For some years now, in addition to the aforementioned block (ingot) Casting process also tape casting process used in practice. The material is taken directly from the Poured melt in ribbon form as a 1-40 mm thick ribbon and then warn and then cold or directly cold out? Final thickness rolled on.

It has now been found that when comparing those made from cast strips and cast bars Aluminum strips, the former generally show higher roughening after the same etching treatment. This effect is Detectable on both unalloyed and alloyed aluminum metal.

The invention therefore relates to a method for producing aluminum electrodes for electrolytic capacitors, which are electrolytically etched in a chloride-containing electrolyte for the purpose of increasing the surface area, characterized in that that the aluminum tape used for etching

409821/0544

the melt phase is cast directly as a strip and then rolled to the final thickness,. .,

Presumably the better etching behavior of the after the strip casting produced material due to the fundamentally higher rate of solidification during casting.

Examples

One continuous cast bar each made of Al 99 and AlMn became 2 Annealed for hours at 5GO ° C and then to a flattened thickness hot-rolled for 6 minutes and cold-rolled to 0.05 mm thick strips without heat treatment. In comparison it was One strip each from an Al 99 melt and from an AlMn melt in a strip casting system directly as a 7 mm thick Cast strip and then rolled to the same final thickness without heat treatment. The tapes have been degreased and then in an aqueous solution of 20 $ NaCl at 90 C

2 etches, at a current density of 100 A / dm and a current

• 2

amount of 3000 cb / dm.

The capacity was determined according to DIN kl 330 at 0 and 10 volts in a saturated ammonium pentaborate solution with a bath resistance of 60 to 70 ohms. cm at room temperature. The mechanical characteristics of the belts before etching were also determined. The results are summarized in the following tables:

409821 / 0S4A

Example 1 with Al 99

2
(kp / mm) ^ 100
(Ji) 2
Capacity in uP / cm
according to DIN Il 330
0 volts 10 volts 28 23.2 3.3 110 10 Ingot casting 21.0 3.1 150 Bandgus s

Example 2 with AlHn

G-B r
° 100 2
Capacity in uP / cm
according to DIN Il 330 10 volts
60
100 Ingot casting
Strip casting (kp / mm)
32.5
32.9 2.5
3.8 0 volts
210
350

The results show that the strength in the hard state is independent of the casting method. The result of the etching and the capacity measurement, on the other hand, shows a significant increase in capacity in the case of metal that was manufactured using the strip casting process.

409821 / 05AA

Claims (2)

Expectations 1.) Process for the production of aluminum electrodes for Electrolytic capacitors, which are electrolytically in a chloride-containing electrolyte for the purpose of increasing the surface area are etched, characterized in that the for etching. The aluminum strip used was cast directly as a strip from the melt phase and then cast to its final thickness is rolled " 2. The method according to claim 1, characterized in that the cast strip thickness is between 1 and 40 mm. ALUMINUM ROLLING MILLS SNGEN GMBH FJP-Kr / Sche
4.9.72-730- 409821/0544