JPS6187802A - Production of aluminum-titanium alloy powder - Google Patents

Abstract

PURPOSE:To obtain Al-Ti alloy powder suitable for production of a product having an improved electrical characteristic in the stage of converting a powder mixture composed of Al powder and Ti powder by a heating treatment to an Al-Ti alloy and crushing said alloy by controlling the density of the powder mixture and subjecting the powder mixture to the heating treatment. CONSTITUTION:The alloy powder is produced by subjecting the powder mixture composed of the aluminum powder and titanium hydride powder or the aluminum powder and titanium powder to the heating treatment to form the aluminum-titanium alloy and crushing the alloy. The heating treat is executed in this stage by controlling the density of the powder mixture to a 1/15d+0.35-1/15d+1.6 range (d is the average grain size of the titanium hydride powder or titanium powder in micron). The aluminum-titanium alloy powder suitable for the anode electrode of an electrolytic capacitor in thus obtd.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for producing an aluminum and titanium alloy powder used in an electrolytic capacitor using an aluminum and titanium alloy as an anode metal, and particularly relates to a method for producing an aluminum and titanium alloy powder used in an electrolytic capacitor using an aluminum and titanium alloy as an anode metal. The present invention relates to a method for defining, heat-treating, and then crushing. (Prior art) Traditionally, when producing a multi-element composition using powder metallurgy techniques using different types of powders as raw materials, the raw material powders are first mixed, preheat-treated, and then coarsely crushed. After molding into a shape close to the desired shape, a product with the desired shape was manufactured by subjecting it to heat treatment. This powder metallurgy technique is also commonly used to produce powdered gold powder for sintered 'ttM capacitors. Generally, the sintered body of a sintered electrolytic capacitor using aluminum-titanium alloy powder is porous and designed to have a large surface area.

In this case, the degree of aluminum and titanium alloy powder and the pore structure are important factors in producing the sintered body. If the particle size of the alloy powder is fine, the flowability of the powder will be poor.
The process of automatically filling a mold with powder and forming the mold has the drawbacks that it takes time to fill the powder and that the filled powder varies greatly. Furthermore, when the pore structure inside the alloy powder becomes finer, it has the disadvantage that the dielectric loss of the electrolytic capacitor product becomes larger and the frequency change of capacitance becomes larger. In other words, if the density of the mixed powder of aluminum and titanium during heat treatment is extremely low, the particle size of the alloy powder that is coarsely crushed by heat treatment will become finer. Conversely, if the density of the mixed powder is increased, the heat treatment The resulting alloy blocks become hard, making it difficult to crush them, and the pore structure of the alloy powder becomes finer.

(Object of the Invention) The present invention has been made to eliminate these drawbacks.

(Structure of the Invention) The present invention provides a method for producing aluminum-titanium alloy powder, in which the density of mixed powder is reduced from 1/15 d+0.35 to 1
/15 d + 1.6.

(Example 1) In this example, titanium hydride powder with an average particle size of 3.0 μm, titanium hydride powder with an average particle size of 5.0 μm, and aluminum powder with an average particle size of 5.5 μm were used. Hydrogen ratio titanium powder and aluminum powder were mixed at a ratio of 59:41, and the mixed powder was compressed to a density under the conditions shown in Table 1 at a temperature of 650°C and a pressure of 10-3 mmHg. Heat treatment was performed in a high-temperature vacuum under the following conditions. In addition, the bulk density of this mixed powder is 0.4 for titanium hydride powder of 3 μm.
1 g/cm3, and 0.55 g/am'' for 5 μm titanium hydride powder.This heat-treated block of alloy was 44 μm (mesh number 325).
Using a commercially available electronic sieve, we investigated how much fine-grained powder could be removed from the alloy block.

Enter the results in percentages in Table 1. Further 44μm
The alloy block remaining on the sieve was transferred to a 500 μm (mesh number 32) sieve, a urethane-coated lead core ball was placed therein, and the mixture was passed through an electric sieve. This operation means coarsely crushing the alloy block on a sieve, and when it becomes 500 μm or less, sifting it with a sieve to obtain alloy powder with a size of 500 μm or less. At this time, the time for coarse crushing through the electric sieve was set at 5 minutes, and if 5% or more of the alloy blocks remained on the sieve, the time was further extended to sieve until 5% or less of the alloy blocks remained. The rough crushing time at this time is entered in Table 1. In addition, if the number of alloy blocks did not decrease to 5 or less even after carrying out the test for 1 hour, the amount of alloy blocks remaining on the sieve was recorded. The powder thus obtained and the light
The powder obtained by passing through a μm sieve was mixed and then compounded with camphor as a binder. This powder is molded using an automatic powder molding machine capable of automatic powder filling, and the temperature is 1150.
A sintered body was produced by vacuum sintering at a temperature of 10-3 mmHg or less. Measure the weight of these 20 sintered bodies, calculate the σ value from the variation in weight, and calculate the σ value as a percentage (σ value/
The average value) was entered in Table 1. Furthermore, this sintered body was anodized using a known solid electrolytic capacitor forming method to form an oxide film and provide a dielectric layer, and then a manganese oxide layer and a cathode layer were formed, and an insulating exterior was applied to produce a solid electrolytic capacitor. . The frequency dependence of the capacitance of these 10 solid electrolytic capacitors was measured. Frequency 120Hz and 1QkHz
The changes in the static capacitance of z were calculated, and the average values of the 10 values were entered in percentages in Table 1.

From Table 1 and above, from the results entered in Table 1, the aluminum-titanium alloy powder obtained by heat-treating the mixed powder while keeping the bulk density is extremely easy to crumble, and there are many powders with a diameter of 44 μm or less. The flowability deteriorates and the weight variation of the sintered body increases. This variation becomes smaller by increasing the density. The weight of the sintered body is proportional to the capacitance, and the standard range of capacitance is ±20 inches according to the Japanese Industrial Standards, so it is industrially desirable to keep the 3σ value of capacitance variation within about 20 inches. In this sense, the σ value of the weight variation of the sintered body must be within 6.6 inches.

The points with the lowest density that satisfy this are plotted in FIG. As the density of the mixed powder increases, the heat-treated alloy blocks become harder and coarse crushing becomes difficult.

Even if the alloy blocks remaining on the 500 μm sieve after being crushed for 1 hour using the method of this example are crushed manually using an agate mortar, they become very hard and difficult to crush.

In particular, it was found that if more than 50 pieces remained on a 500 μm sieve, it could not be crushed manually.

Furthermore, as the density of the mixed powder increases, the pore structure of the heat-treated alloy becomes finer, making coarse crushing difficult and increasing the frequency change in the capacitance of the product. For this reason, excessively increasing the density of the mixed powder impairs its industrial value. It was determined that the conditions under which coarse crushing could be achieved by the coarse crushing method of this example were of industrial value, and the points with the highest density that satisfied these conditions were plotted in FIG.

(Example 2) In this example, when the particle size of titanium hydride powder was changed,
In addition, cases in which the particle size of the titanium powder is changed, cases in which the density of the mixed powder is decreased, and cases in which the density is increased will be explained. The conditions under which it was carried out are shown in Table 2. The aluminum powder used had an average particle size of 5.5 μm as in Example 1. A solid electrolytic capacitor was manufactured in exactly the same manner as in Example 1 according to the conditions in Table 2,
In addition, each measurement value was evaluated using exactly the same method. Enter the results in Table 2. Note that among the conditions in Table 2, the condition with the lowest density was the one conducted at the bulk density.

Table 2 The same tendency as in Example 1 was observed in this example as well.

The same industrial value judgment as in Example 1 is made, and the lowest and highest points of density that satisfy this are plotted in FIG. If we connect these plotted points with a reasonable line and express it, the one with higher density is (1/15d+1.6) g/
It can be expressed as am3, and the lower density is (1/15d+
0.35) g/Cm3 expression sulcotocatekyl.

However, d is the average particle size of titanium hydride or titanium powder, and the unit is micron.

As the particle size of titanium hydride powder and titanium powder increases, the capacitance per unit becomes smaller, which goes against the recent trend towards miniaturization. In particular, this tendency increases when the particle size becomes 10 μm or more, so this was not explained in the Examples, but it is clear that the present invention can be extrapolated to the right side of FIG. 1 even for powders with a particle size of 10 μm or more. It is.

(Effects) As explained above, the method for producing aluminum-titanium alloy powder according to the present invention, which involves determining the density of mixed powder and processing it, greatly increases the production capacity of the process and improves the electrical characteristics of exhibited products. It has an industrial effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an average particle diameter-compression density correlation diagram showing the compaction density of a mixed powder with respect to the mean particle diameter of titanium hydride powder and titanium powder. In the figures, (A) a...connecting points with low density of mixed powder related to the production method of the present invention, (B) line...related to the production method of the present invention It connects the density points of the mixed powder. Section f $J勺&f≦

Claims (1)

[Claims] A method for producing an aluminum-titanium alloy powder, comprising the steps of heat-treating aluminum powder and titanium hydride powder or a mixed powder of aluminum powder and titanium powder to form an aluminum-titanium alloy, and coarsely crushing the alloy. , the density of the mixed powder is 1/15d+0
．． 35 to 1/15d+1.6 (where d is the average particle size of titanium hydride powder or titanium powder, expressed in microns).