JP2006144122A - Aluminum material for electrolytic capacitor and its production method, production method of electrode material for electrolytic capacitor, anode material for electrolytic capacitor, and aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum material for an electrolytic capacitor which is inexpensive and has high electrostatic capacity, and its production method and the like. <P>SOLUTION: The aluminum material has a composition having ≥99.9 mass% aluminum purity and containing, by mass, 0.006 to 0.018% Si, 0.006 to 0.018% Fe and 0.0005 to 0.008% Cu. Moreover, a proportion of Al<SB>6</SB>Fe/Al<SB>3</SB>Fe, among Al-Fe intermetallic compounds extracted by a thermal phenol dissolution method, is controlled to ≤0.5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aluminum material for an electrolytic capacitor used as an electrode material for an electrolytic capacitor having a high capacitance and a method for producing the same, a method for producing an electrode material for an electrolytic capacitor, an anode material for an electrolytic capacitor, and an aluminum electrolytic capacitor.

  In this specification, the term “aluminum” is used to include the alloy thereof, and the aluminum material includes a foil, a plate, and a molded body using these.

  For electrode materials for electrolytic capacitors, particularly those used for anodes, the surface area is generally increased by electrolytic etching. As the aluminum material used for this purpose, a high-purity aluminum material having an aluminum purity of 99.98% or more is used. This is because the presence of impurities exceeding the allowable amount increases the amount of aluminum dissolved and makes it difficult to form fine etch pits. In addition, when this impurity forms an intermetallic compound in aluminum and the chemical solubility of the interface between the intermetallic compound alone or the aluminum matrix is high, the influence on the shape control of this etch pit becomes very large. .

For such problems, for example, a method of regulating the precipitation amount of Fe or Si (Patent Document 1), a method of regulating the precipitation amount of Fe, Si, and Cu (Patent Document 2), an Fe-containing intermetallic compound A method of regulating the size and Fe content of the iron is disclosed (Patent Document 3).
Japanese Patent Publication No. 3-61333 JP-A-8-209275 JP 2004-149835 A

  However, due to the recent demand for cost reduction, if an attempt is made to use an inexpensive aluminum lump, the content of unavoidable impurities in aluminum, in particular, Fe, Si, Cu, is inevitably increased. There is a problem that it is difficult to obtain the capacitance.

  An object of the present invention is to provide an aluminum material for an electrolytic capacitor that has a high capacitance and is inexpensive, a method for producing the same, a method for producing an electrode material for an electrolytic capacitor, and an aluminum electrolytic capacitor.

  The above object is achieved by the following means.

(1) The purity of aluminum is 99.9% by mass or more, Si: 0.006% by mass to 0.018% by mass, Fe; 0.006% by mass to 0.018% by mass, Cu; 0 The ratio of Al ₆ Fe / Al ₃ Fe is 0.5 or less among Al—Fe-based intermetallic compounds having a composition of 0005 mass% to 0.008 mass% and extracted by a hot phenol dissolution method. Aluminum material for electrolytic capacitors, characterized by being regulated by

(2) The purity of aluminum is 99.9% by mass or more, Si: 0.006% by mass to 0.012% by mass, Fe; 0.006% by mass to 0.012% by mass, Cu; 0 The ratio of Al ₆ Fe / Al ₃ Fe is regulated to 0.7 or less among the intermetallic compounds having a composition of 0005 mass% to 0.006 mass% and extracted by the hot phenol dissolution method. An aluminum material for electrolytic capacitors.

  (3) In the preceding item 1 or 2, wherein the Fe content in the intermetallic compound of Fe measured by the hot phenol dissolution method is in the range of more than 10% and 50% or less of the Fe content in the aluminum material The aluminum material for electrolytic capacitors as described.

  (4) The recrystallization rate is 60% or more, the average crystal grain size of the recrystallized grains is 0.03 mm or more and 0.8 mm or less, and among the recrystallized grains, cubic orientation grains measured from the surface are used. 4. The aluminum material for electrolytic capacitors as described in any one of 1 to 3 above, wherein the area occupancy is less than 20%.

  (5) The aluminum material for electrolytic capacitors as described in any one of 1 to 4 above, wherein the tensile strength is 72 MPa or more and 92 MPa or less.

  (6) The aluminum material for electrolytic capacitors as described in any one of 1 to 5 above, which is a low-pressure anode material.

  (7) The purity of aluminum is 99.9% by mass or more, Si: 0.006% by mass to 0.018% by mass, Fe; 0.006% by mass to 0.018% by mass, Cu; 0 An aluminum ingot having a composition of not less than 0005% by mass and not more than 0.008% by mass is used at a temperature of from 20 ° C. to 630 ° C. for 1 hour to 50 hours before or after chamfering performed on the aluminum ingot. For 5 minutes to 20 hours at a temperature of 420 ° C. or higher and 520 ° C. or lower during hot rolling or after hot rolling, and then performing cold rolling and final annealing. A method for producing an aluminum material for electrolytic capacitors.

  (8) The purity of aluminum is 99.9% by mass or more, Si: 0.006% by mass to 0.012% by mass, Fe; 0.006% by mass to 0.012% by mass, Cu; 0 An aluminum ingot having a composition of not less than 0005% by mass and not more than 0.006% by mass is used at a temperature of 520 ° C. or more and 630 ° C. or less for 1 hour or more and 50 hours or less before or after chamfering performed on the aluminum ingot. To perform a homogenization treatment at a time of, and during hot rolling or after hot rolling, hold at a temperature of 420 ° C. or higher and 520 ° C. or lower for 1 minute or longer and 20 hours or shorter, and then perform cold rolling and final annealing. A method for producing an aluminum material for electrolytic capacitors.

  (9) The aluminum material for electrolytic capacitors as described in (7) or (8) above, wherein after the cold rolling, final annealing is performed at a temperature of 250 ° C. or higher and 330 ° C. or lower for a time of 1 hour or longer and 10 hours or shorter. Manufacturing method.

  (10) The method for producing an aluminum material for electrolytic capacitors as described in (9) above, wherein heat treatment is performed at a temperature of 150 ° C. or higher and 220 ° C. or lower for 1 hour or more and 24 hours or less prior to the final annealing.

  (11) The aluminum material for electrolytic capacitors as described in (7) or (8) above, wherein after the cold rolling, final annealing is performed at a temperature of 370 ° C. or more and 470 ° C. or less for a time of 1 hour or more and 10 hours or less. Manufacturing method.

  (12) 5% to 30% of a foil or plate material having a thickness of 80 μm to 150 μm and subjected to final annealing at a temperature of 430 ° C. to 550 ° C. for 1 hour to 10 hours after cold rolling. 9. The method for producing an aluminum material for electrolytic capacitors as described in 7 or 8 above, wherein the additional rolling is performed at a rolling reduction of not more than%.

  (13) A method for producing an electrode material for electrolytic capacitors, comprising a step of etching the aluminum material according to any one of items 1 to 6.

  (14) The method for producing an electrode material for electrolytic capacitors as described in 13 above, wherein at least a part of the etching is AC etching.

  (15) An electrolytic capacitor anode material produced by the production method according to item 13 or 14 above.

  (16) An aluminum electrolytic capacitor characterized in that an aluminum electrode material manufactured by the manufacturing method according to the above item 13 or 14 is used as the electrode material.

According to the invention described in the preceding item (1), although an inexpensive aluminum material having a large amount of Fe is used, the ratio of Al ₆ Fe / Al ₃ Fe is regulated to 0.5 or less, thereby expanding by etching. An aluminum material for electrolytic capacitors having a high surface area and a high capacitance can be obtained.

According to the invention described in the preceding item (2), although an inexpensive aluminum material having a large amount of Fe is used, the ratio of Al ₆ Fe / Al ₃ Fe is restricted to 0.7 or less, thereby expanding by etching. An aluminum material for electrolytic capacitors having a high surface area and a high capacitance can be obtained.

  According to the invention described in item (3) above, since the Fe content in the Fe intermetallic compound is regulated to be in the range of more than 10% and less than 50% of the Fe content in the aluminum material, Is suppressed, and a further excellent capacitance can be realized.

  According to the invention described in item (4) above, since the recrystallization rate, the average crystal grain size, and the area occupancy ratio of the cubic orientation grains are defined within a predetermined range, a further excellent capacitance can be realized.

  According to the invention described in item (5) above, since the tensile strength is 72 MPa or more and 92 MPa or less, it is possible to suppress the fracture at the time of etching and to make the aluminum material for electrolytic capacitors easy to handle.

  According to the invention described in item (6) above, an inexpensive low-pressure anode material excellent in capacitance can be obtained.

  According to the invention described in item (7) above, an aluminum material for electrolytic capacitors having a large surface area ratio by etching and a high capacitance can be produced.

  According to the invention described in item (8) above, it is possible to manufacture an aluminum material for electrolytic capacitors having a high capacitance with a large area expansion by etching.

  According to the invention described in item (9) above, uniform and fine etch pits can be generated, and an aluminum material for electrolytic capacitors having a high capacitance can be reliably produced.

  According to the invention described in item (10) above, formation of coarse etch pits can be suppressed, and an aluminum material for electrolytic capacitors having a high capacitance can be reliably manufactured.

  According to the invention described in item (11) above, uniform and fine etch pits can be generated, and an aluminum material for electrolytic capacitors having a high capacitance can be reliably produced.

  According to the invention described in item (12) above, it is possible to produce an aluminum material for electrolytic capacitors that can suppress breakage during etching, is easy to handle, and has excellent electrostatic capacity.

  According to the invention described in the preceding item (13), it is possible to provide an inexpensive electrode material for an electrolytic capacitor having a large area expansion ratio and a high capacitance.

  According to the invention described in item (14), since at least a part of the etching is AC etching, an electrode material having a high electrostatic capacity can be provided by forming spongy etch pits.

  According to the invention described in the preceding item (15), it can be an inexpensive anode material for electrolytic capacitors excellent in electrostatic capacity.

  According to the invention described in the above item (16), an aluminum electrolytic capacitor having a large area expansion ratio and an inexpensive electrode material and having a high capacitance can be obtained.

  Next, the configuration of the present invention and the reason thereof will be described.

  In the present invention, in the low-pressure material for electrolytic capacitors, in order to enable the application of an inexpensive aluminum material having a high Fe content, by controlling the amount, size and state of Al-Fe-based precipitates, A material with good etching characteristics was developed.

  Regarding the improvement of Al—Fe-based intermetallic compounds and etching characteristics, the above-mentioned Japanese Patent Publication No. 3-61333 discloses the precipitation amount of Fe and Si, and JP-A-8-209275 discloses the precipitation amount of Fe, Si, and Cu. JP 2004-149835 discloses a technique regarding the shape, size and amount of an intermetallic compound. These are effective methods for pit control during etching, but as the amounts of Fe and Si increase, the control of etch pits becomes increasingly difficult. The present invention solves this problem by controlling the phase of the intermetallic compound.

  First, if the amount of Fe is less than 0.006% by mass, an increase in cost due to the raw material lump to be used cannot be avoided, and the effect of the present invention cannot be expected. Moreover, when it contains exceeding 0.018 mass%, melt | dissolution weight loss will increase remarkably and will cause a capacitance fall and a capacitance variation.

  Next, when the Si amount is less than 0.006% by mass, an increase in cost due to the raw material lump to be used cannot be avoided, and the effect of the present invention cannot be expected. Moreover, when it contains exceeding 0.018 mass%, melt | dissolution weight loss will increase remarkably by coexistence effect with Fe, and will cause a capacitance fall and a capacitance variation.

  Further, if the amount of Cu is less than 0.0005% by mass, an increase in cost due to the raw material lump to be used cannot be avoided, and the effect of the present invention cannot be expected. On the other hand, when the content is 0.008% by mass or more, the dissolution weight loss is remarkably increased, which causes a decrease in capacitance and a variation in capacitance.

  Further, it is desirable that the other impurity elements are each in the range of 200 ppm or less.

As a result of diligent investigations on materials that do not impair the etching characteristics of the aluminum material having the above composition range, the inventor can control the ratio of Al ₆ Fe to Al ₃ Fe among Al—Fe-based intermetallic compounds. The present invention was found to be very effective, and the present invention was completed.

Specifically, among the intermetallic compounds extracted by the hot phenol dissolution method, the ratio between the peak intensity of Al ₆ Fe and the peak intensity of Al ₃ Fe in the X-ray diffraction pattern, and control of Al ₆ Fe / Al ₃ Fe are controlled. It is to do. As an example of phase identification of an intermetallic compound in an Al-Fe alloy, for example, the following literature (1) in an aluminum ingot of Al-0.6% Fe and Al-0.8% Fe, Al-0. (2) published patent gazettes and the like in the cathode foil of 02 to 0.15% Fe. According to such a method, the strength of Al ₆ Fe and Al ₃ Fe can be quantified. We have found that the Al ₆ Fe / Al ₃ Fe ratio related to the etching characteristics of the electrolytic capacitor foil is greatly related in the composition range where the Fe content is 0.018% by mass or less. For this determination, Al ₆ Fe is used for ICDD card No. No. 47-1433, d = 0.4879 nm, Al ₃ Fe is an ICDD card No. It is calculated | required by using d = 0.2095nm described in 29-0042.

(1) Kominato, Takada: Light Metal 29 (1979), p64
(2) JP 2002-124438 A This Al ₆ Fe / Al ₃ Fe ratio is Si: 0.006 mass% or more and 0.018 mass% or less, Fe; 0.006 mass% or more and 0.018 mass% or less Cu: In the composition range of 0.0005 mass% or more and 0.008 mass% or less, it is necessary to be 0.5 or less. The reason for this is that if it exceeds 0.5, the fine etching pits that greatly contribute to the surface expansion rate easily fall off. Further, the preferred Al ₆ Fe / Al ₃ Fe ratio is 0.4 or less, and the optimum range is 0.3 or less.

When the upper limit of the Si content is 0.012% by mass or less, the upper limit of the Fe content is 0.012% by mass or less, and the upper limit of the Cu content is 0.006% by mass or less, the solubility itself of the material is low. Therefore, the Al ₆ Fe / Al ₃ Fe ratio is allowed to 0.7. If the ratio exceeds 0.7, fine etching pits are likely to drop off, resulting in a decrease in capacitance and variations. Further, the preferred Al ₆ Fe / Al ₃ Fe ratio is 0.5 or less, and the optimum range is 0.3 or less.

  Next, regarding the total content of Fe-based intermetallic compounds, the amount of dissolution loss decreases when the Fe content of Fe-based intermetallic compounds is less than 10% of the Fe content in the aluminum material. If it exceeds 50%, the generation ratio of coarse etch pits increases, and the capacitance tends to decrease. A more desirable range of the total content of Fe-based intermetallic compounds is 10% to 40%, and an optimum range is 10% to 30%.

  The present invention is subjected to etching as a semi-hard material subjected to final annealing treatment or after the final annealing treatment to give a processing strain of up to 30%, but the recrystallization rate at the last annealing is an etching property. affect. That is, when the non-recrystallization rate increases, the etching pattern becomes non-uniform, resulting in a decrease in capacitance. In this case, the recrystallization rate must be 60% or more, and it is effective that the average crystal grain size of the recrystallized grains is 0.03 mm or more and 0.8 mm or less. In the case of the present invention, the area occupancy ratio of the cube-oriented grains measured from the surface is advantageous for further improvement of the capacitance by avoiding the mixture of non-cubic grains and cube-oriented grains. The area occupancy of the cubic oriented grains is preferably less than 20%. Further, the recrystallization rate is preferably 80% or more, the average crystal grain size of the recrystallized grains is 0.05 mm or more and 0.6 mm or less, and the optimum range is 0.05 mm or more and 0.3 mm or less. Further, the area occupancy of the cubic orientation grains is more preferably less than 15%, and the optimum range is less than 10%.

  Next, the manufacturing method of the said aluminum material is demonstrated. Although the manufacturing method of the aluminum material for electrolytic capacitors is not particularly limited, it is generally manufactured by sequentially performing each step of face milling, hot rolling, cold rolling, and final annealing on an aluminum ingot. In this embodiment, as a desirable manufacturing method, the purity of aluminum is 99.9% by mass or more, and Si: 0.006% by mass to 0.018% by mass, Fe; 0.006% by mass to 0.018% Using an aluminum ingot having a composition of not more than mass%, Cu; 0.0005 mass% or more and 0.008 mass% or less (hereinafter referred to as A composition), before or after chamfering performed on the aluminum ingot. A homogenization treatment is performed at a temperature of 630 ° C. or less for 1 hour or more and 50 hours or less, and held at a temperature of 420 ° C. or more and 520 ° C. or less for 5 minutes or more and 20 hours or less during hot rolling or after hot rolling. Then, a method of performing cold rolling and final annealing is mentioned.

  Moreover, the purity of aluminum is 99.9 mass% or more, Si; 0.006 mass% or more and 0.012 mass% or less, Fe; 0.006 mass% or more and 0.012 mass% or less, Cu; An aluminum ingot having a composition of 0005 mass% or more and 0.006 mass% or less (hereinafter referred to as B composition) is used at a temperature of 520 ° C. or more and 630 ° C. or less before or after chamfering performed on the aluminum ingot. A homogenization treatment is performed for a time of not less than 50 hours and not more than 50 hours, and during hot rolling or after hot rolling, it is maintained at a temperature of 420 ° C. or more and 520 ° C. or less for 1 minute or more and 20 hours or less, and then cold rolling and final annealing The method of implementing is also mentioned.

The homogenization treatment is performed for the purpose of re-dissolving coarse intermetallic compounds in aluminum and changing the state of Al ₆ Fe to Al ₃ Fe, but the purpose is achieved at less than 520 ° C. or less than 1 hour. If the temperature exceeds 630 ° C. or exceeds 50 hours, coarse recrystallized grains are generated during hot rolling, and the recrystallized grains during hot rolling are increased, thereby inhibiting the uniformity of the structure.

  A more desirable heating range for the homogenization treatment is 3 hours to 30 hours at a temperature of 520 ° C. to 590 ° C., and an optimum range is 4 hours to 20 hours at a temperature of 530 ° C. to 560 ° C.

As an example of the heat treatment during or after the hot rolling, the step of holding during hot rolling, the method of batch annealing the hot rolled coil, or the continuous coil annealing treatment may be used. . The heat treatment during hot rolling or after hot rolling is aimed at preferential production of Al ₃ Fe, but the heating temperature is less than 420 ° C., less than 1 minute (in the case of B composition) or less than 5 minutes ( In the case of composition A), the purpose may not be achieved, and if it exceeds 520 ° C. or exceeds 20 hours, the recrystallized grain size after hot rolling increases, and the recrystallized structure at the time of final annealing is increased. It becomes non-uniform. A more desirable range of heat treatment conditions during hot rolling or after hot rolling is 5 minutes to 15 hours at a temperature of 440 ° C. or higher and 480 ° C. or lower, and the heating time is particularly preferably 10 minutes or longer and 10 hours or shorter. is there.

  Further, cold rolling is performed subsequent to the heat treatment during or after the hot rolling, and then at a temperature of 250 ° C. or higher and 330 ° C. or lower for 1 hour or longer and 10 hours or shorter, or 370 ° C. or higher and 550 ° C. or lower (more preferably Final annealing at a temperature of 370 ° C. to 470 ° C. for 1 hour to 10 hours is performed for the purpose of improving etching characteristics. If the temperature is less than 250 ° C., recrystallization does not proceed sufficiently, and non-recrystallized regions and recrystallized regions coexist, resulting in non-uniform etch pits and reduced capacitance. Further, in a temperature range of more than 330 ° C. and less than 370 ° C., the total amount of intermetallic compounds containing Fe becomes too large, and fine etch pits are hardly formed. Further, in a temperature range exceeding 550 ° C., the strength of the material is remarkably reduced, and the etching magnification must be reduced to suppress breakage during coil etching, resulting in a decrease in capacitance. A more desirable range of this final annealing can be 290 ° C. or higher and 330 ° C. or lower, or 380 ° C. or higher and 430 ° C. or lower. The time is 1 hour or more and 7 hours or less, and the optimum range is 1 hour or more and 5 hours or less.

  Furthermore, when the final annealing is performed at a temperature of 250 ° C. or higher and 330 ° C. or lower, the processing strain is released in advance by increasing or maintaining the passage time in the temperature range from 150 ° C. to 220 ° C. prior to this. The formation of coarse etch pits can be suppressed by controlling the precipitation of intermetallic compounds containing Fe. At this time, the necessary passing time or holding time in the temperature range of 150 ° C. or higher and 220 ° C. or lower is 1 hour or longer and 24 hours or shorter, more preferably 180 ° C. or higher and 220 ° C. or lower and 2 hours or longer and 22 hours or shorter, The optimum range is 200 ° C. or more and 220 ° C. or less and 10 hours or more and 20 hours or less.

  In addition, a more desirable range of final annealing when the final annealing is performed at a temperature of 430 ° C. or higher and 550 ° C. or lower and additional rolling is performed at a rolling reduction of 5% or higher and 30% or lower is 430 ° C. or higher and 490 ° C. or lower, time Is about 1 hour to 7 hours, and the optimum range is 440 ° C. to 480 ° C. for 1 hour to 5 hours. A more desirable range of the rolling reduction is 10% to 25%, and an optimum range is 12% to 22%.

  The aluminum material thus produced preferably has a tensile strength of 72 MPa to 92 MPa. If it is less than 72 MPa, there is a risk of fracture during coil etching, and the etching magnification must be reduced, resulting in a decrease in capacitance. If it exceeds 92 MPa, handling during coil etching becomes inconvenient.

  The aluminum material manufactured as described above is subjected to an etching process for improving the area expansion ratio to obtain an electrode material for an electrolytic capacitor. Although the etching process conditions are not particularly limited, it is preferable to adopt the AC etching method at least partially. By the AC etching method, a spongy etching structure having a large area expansion ratio is generated, and a high capacitance is realized.

  After the etching treatment, it is desirable to perform a chemical conversion treatment to make an anode material, and in particular, it may be used as an electrolytic capacitor electrode material for low pressure or medium pressure, but it does not prevent its use as a cathode material. . Moreover, the electrolytic capacitor using this electrode material can realize a large capacitance.

[Example 1 (Sample Nos. 1 to 11)]
Aluminum ingots (thickness: 400 mm) having various compositions with round numbers 1 to 8 shown in Table 1 were produced by a semi-continuous casting method.

  A 400 mm thick aluminum ingot selected as shown in Table 2 from the aluminum ingots shown in Table 1 was homogenized under the conditions shown in Table 2, then chamfered and started. Hot rolling was performed at a temperature of 550 ° C.

  Thereafter, the hot-rolled sheet was heated and held in a nitrogen atmosphere under the conditions shown in Table 2, followed by cold rolling to obtain a foil having a thickness of 0.100 mm. The foil was subjected to final annealing at 300 ° C. for 1 hour.

  In addition, about sample No9, the homogenization process was not implemented. Moreover, about sample No10, the heat holding | maintenance of the hot rolled sheet was not implemented.

About the aluminum material for electrolytic capacitors thus obtained, the intermetallic compound was extracted and analyzed under the following conditions, the ratio of Al ₆ Fe / Al ₃ Fe was measured, and the amount of Fe in the intermetallic compound was Fe in the aluminum material. The ratio to the content (in Table 2, indicated as Fe ratio in the intermetallic compound) was calculated. Subsequently, the electrostatic capacity was measured by performing etching and chemical conversion treatment under the following conditions.

  The results are shown in Table 2. The capacitance is shown by relative comparison with the capacitance of sample No. 10 being 100.

<Intermetallic compound extraction method and analysis method>
Insert the sample into the dehydrated phenol and heat. After the sample is completely decomposed, cool to about 140 ° C. and add benzyl alcohol. Suction-filter using a 0.1 μm PTFE membrane filter, wash with benzyl alcohol and acetone, and use as a sample for analysis.

The residue collected on the PTFE membrane filter is scraped and analyzed by X-ray diffraction, and aqua regia (35% by mass hydrochloric acid: 60% by mass nitric acid = 3: 1) and pure water are mixed at a ratio of 1: 1. The obtained solution is dissolved in an aqueous kunnic acid (hydrochloric acid + nitric acid) solution, and the amount of Fe in the intermetallic compound is quantified with an ICP emission spectroscopic analyzer.
<Etching evaluation method>
Etching was performed using an aqueous solution of hydrochloric acid 1.8 mol / L + H ₂ SO ₄ 0.02 mol / L as the etchant, temperature 55 ° C, sine wave AC 30 Hz, current density AC 0.3 A / cm ² (single side), time 300 sec. went.

Furthermore, in an aqueous solution of ammonium adipate (150 g / L, 85 ° C), a chemical conversion treatment is performed at a current density of 50 mA / cm ² with a constant voltage conversion treatment of 20 V x 10 min, and a heat treatment is performed in an atmosphere of 500 ° C x 2 min. After that, re-chemical conversion was performed for 2 minutes under the same conditions to form a dielectric oxide film.

As understood from the results shown in Table 2, the product according to the present invention has a ratio of Al ₆ Fe / Al ₃ Fe of 0.5 or less or 0.7 or less, and the amount of Fe in the intermetallic compound is based on the total amount of Fe. It can be seen that the ratio is more than 10% and 50% or less, and the capacitance is superior to the comparative product in which the ratio of Al ₆ Fe / Al ₃ Fe exceeds 0.7.
[Example 2 (Sample Nos. 21 to 28)]
A 400 mm thick aluminum ingot selected as shown in Table 3 from the aluminum ingots shown in Table 1 was homogenized under the conditions shown in Table 3, followed by chamfering and starting. Hot rolling was performed at a temperature of 550 ° C.

  Thereafter, during hot rolling, the hot rolled plate was heated and held in a nitrogen atmosphere under the conditions shown in Table 2 and subsequently hot rolled to obtain a hot rolled plate having a thickness of 10 mm. Subsequently, cold rolling was performed to obtain a foil having a thickness of 0.100 mm, and final annealing was performed on the foil at 290 ° C. × 1 hour or 10 hours.

  In addition, about sample No23, before implementing final annealing of 290 degreeC x 10 hours, 210 degreeC x 18 hours heat processing were performed. Moreover, about sample No. 25 and 27, the heat holding | maintenance of the hot rolled sheet was not implemented.

With respect to the aluminum material for electrolytic capacitors thus obtained, an intermetallic compound was extracted and analyzed in the same manner as in Example 1, and the ratio of Al ₆ Fe / Al ₃ Fe was measured. In addition, the recrystallization rate was examined and the cube orientation occupation rate was also examined by the following method.

Next, the capacitance was measured by performing etching and chemical conversion treatment under the same conditions as in Example 1. The results are shown in Table 3. The capacitance is shown by relative comparison with the capacitance of sample No. 10 in Table 2 as 100.
<Measurement method of recrystallization rate>
The surface of the aluminum material was polished with emery paper, subjected to rough buffing and finish polishing, and then washed with water and dried. Next, the surface of the polished aluminum material was anodized using a positive electrode. The anodizing treatment was performed using Barker's solution (3 ± 1% borohydrofluoric acid), bath temperature: 28 ± 1 ° C., applied voltage: 30 V, and applied time: 45 seconds. The anodized sample was observed with a polarizing microscope, and the percentage of clear recrystallized grains in the observation field was determined. The area of the observation visual field is not specified but is preferably 10 mm ² or more.

As understood from the results shown in Table 3, the product according to the present invention has an Al ₆ Fe / Al ₃ Fe ratio of 0.5 or less, a recrystallization ratio of 60% or more, and a cube orientation occupation ratio of 20% or less. Yes, the ratio of Al ₆ Fe / Al ₃ Fe exceeds 0.7, the recrystallization rate is 60% or less, or the capacitance is superior to the comparative product whose cube orientation occupancy exceeds 20% I understand.
[Example 3 (Sample Nos. 31 to 38)]
After chamfering the aluminum ingot having a thickness of 400 mm selected as shown in Table 4 from the aluminum ingots shown in Table 1, homogenization treatment was performed under the conditions shown in Table 4, Subsequently, hot rolling was performed at a starting temperature of 490 ° C. Subsequently, cold rolling was performed to obtain a foil having a thickness of 0.125 mm.

  The foil was finally annealed under the heating conditions shown in Table 4, and Samples Nos. 34 to 37 were additionally rolled at the rolling reduction shown in Table 4.

With respect to the aluminum material for electrolytic capacitors thus obtained, an intermetallic compound was extracted and analyzed under the conditions shown in Example 1, the ratio of Al ₆ Fe / Al ₃ Fe was measured, and the strength was measured. Next, the capacitance was measured by performing etching and chemical conversion treatment under the same conditions as in Example 1.

  The results are shown in Table 4. The capacitance is shown by relative comparison with the capacitance of sample No. 10 in Table 2 as 100.

As understood from the results shown in Table 4, it can be seen that the product of the present invention in which the ratio of Al ₆ Fe / Al ₃ Fe is 0.5 or less is excellent in capacitance. Moreover, from the comparison between sample Nos. 34 to 37 and sample No. 38, it is found that when the final annealing is performed at a high temperature, the strength of the aluminum material cannot be secured unless additional rolling is performed.

Claims (16)

The purity of aluminum is 99.9% by mass or more, and Si: 0.006% by mass to 0.018% by mass, Fe: 0.006% by mass to 0.018% by mass, Cu: 0.0005% by mass % Of Al-Fe-based intermetallic compounds having a composition of not less than 0.008% and not more than 0.008% by mass, and the ratio of Al ₆ Fe / Al ₃ Fe is regulated to 0.5 or less. An aluminum material for electrolytic capacitors, characterized in that The purity of aluminum is 99.9% by mass or more, and Si: 0.006% by mass to 0.012% by mass, Fe: 0.006% by mass to 0.012% by mass, Cu: 0.0005% by mass Among the intermetallic compounds extracted by the hot phenol dissolution method, the ratio of Al ₆ Fe / Al ₃ Fe is regulated to 0.7 or less. Aluminum material for electrolytic capacitors.   The amount of Fe in the intermetallic compound of Fe measured by a hot phenol dissolution method is in the range of more than 10% and not more than 50% of the Fe content in the aluminum material. Aluminum material for electrolytic capacitors.   The recrystallization rate is 60% or more, the average crystal grain size of the recrystallized grains is 0.03 mm or more and 0.8 mm or less, and the area occupancy ratio of cubic oriented grains measured from the surface of the recrystallized grains The aluminum material for electrolytic capacitors according to any one of claims 1 to 3, wherein the content is less than 20%.   The aluminum material for electrolytic capacitors according to any one of claims 1 to 4, wherein the tensile strength is 72 MPa or more and 92 MPa or less.   The aluminum material for electrolytic capacitors according to any one of claims 1 to 5, which is a low-pressure anode material. The purity of aluminum is 99.9% by mass or more, and Si: 0.006% by mass to 0.018% by mass, Fe: 0.006% by mass to 0.018% by mass, Cu: 0.0005% by mass Using an aluminum ingot having a composition of not less than 0.008% by mass and not more than
Before or after chamfering performed on the aluminum ingot, a homogenization treatment is performed at a temperature of 520 ° C. or more and 630 ° C. or less for 1 hour or more and 50 hours or less, and during hot rolling or after hot rolling 420 A method for producing an aluminum material for electrolytic capacitors, characterized by holding at a temperature of from ℃ to 520 ° C. for from 5 minutes to 20 hours, followed by cold rolling and final annealing. The purity of aluminum is 99.9% by mass or more, and Si: 0.006% by mass to 0.012% by mass, Fe: 0.006% by mass to 0.012% by mass, Cu: 0.0005% by mass Using an aluminum ingot having a composition of not less than 0.006% by mass and not more than
Before or after chamfering performed on the aluminum ingot, a homogenization treatment is performed at a temperature of 520 ° C. or more and 630 ° C. or less for 1 hour or more and 50 hours or less, and during hot rolling or after hot rolling 420 The manufacturing method of the aluminum material for electrolytic capacitors characterized by hold | maintaining for 1 minute or more and 20 hours or less at the temperature of 520 degreeC or more and cold rolling and final annealing after that.   9. The production of an aluminum material for electrolytic capacitors according to claim 7, wherein after the cold rolling, final annealing is performed at a temperature of 250 ° C. or more and 330 ° C. or less for 1 hour or more and 10 hours or less. Method.   The method for producing an aluminum material for electrolytic capacitors according to claim 9, wherein a heat treatment is performed at a temperature of 150 ° C or higher and 220 ° C or lower for 1 hour or more and 24 hours or less prior to the final annealing.   9. The production of an aluminum material for electrolytic capacitors according to claim 7, wherein after the cold rolling, final annealing is performed at a temperature of 370 ° C. to 470 ° C. for 1 hour to 10 hours. Method.   5% to 30% of the foil or plate material having a thickness of 80 μm or more and 150 μm or less that has been subjected to final annealing at a temperature of 430 ° C. or more and 550 ° C. or less for 1 hour or more and 10 hours or less after cold rolling. The method for producing an aluminum material for electrolytic capacitors according to claim 7 or 8, wherein additional rolling is performed at a rolling reduction.   The manufacturing method of the electrode material for electrolytic capacitors characterized by including the process of etching the aluminum material of any one of Claim 1 thru | or 6.   The method for producing an electrode material for electrolytic capacitors according to claim 13, wherein at least a part of the etching is AC etching.   The anode material for electrolytic capacitors manufactured by the manufacturing method of Claim 13 or 14. An aluminum electrolytic capacitor, wherein an aluminum electrode material produced by the production method according to claim 13 or 14 is used as the electrode material.