Tungsten Powder, Positive Electrode Body For Capacitors, And Electrolytic Capacitor
A tungsten powder and element technology, applied in the field of tungsten powder, capacitor anode body and electrolytic capacitor, can solve the problems of reduced insulation, low dielectric constant, reduced capacitor capacity, etc., and achieve the effect of good placement characteristics and large capacity
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Embodiment 1
[0065] Put tungsten powder with a volume average particle size of 0.4 μm obtained by hydrogen reduction of commercially available tungsten trioxide into 0.16% by mass of ammonium molybdate aqueous solution and mix well, wash with water and ethanol, and put it into a vacuum dryer to dry Ethanol was removed at 60°C, followed by drying. Next, pair the 5×10 -3 Elemental analysis of the granulated powder obtained by reacting at 1400° C. for 20 minutes under a vacuum condition of Pa showed that the molybdenum element was 0.055% by mass, and the other impurity elements were all 350 mass ppm or less.
Embodiment 2～3 and comparative example 1～3
[0067] Except changing the concentration of the ammonium molybdate aqueous solution in Example 1 as shown in Table 1, tungsten granulated powder was obtained in the same manner. The molybdenum content of the granulated powder obtained in each example was as shown in Table 1, and the other impurity elements were all 350 mass ppm or less.
[0068] The granulated powders produced in Examples 1 to 3 and Comparative Examples 1 to 3 were molded to produce molded bodies with a size of 1.8×3.0×3.5 mm. In this molded body, a tantalum wire with a diameter of 0.29 mm stands vertically on a surface of 1.8×3.0 mm, 2.8 mm is buried inside, and 8 mm is exposed outside. The molded body was subjected to vacuum sintering at 1400° C. for 30 minutes in a high-pressure reduced-pressure furnace to obtain a sintered body with a mass of 145 mg.
[0069]The obtained sintered body was used as an anode body of an electrolytic capacitor. The anode body was chemically converted in 0.1% by mass phosphori...
Embodiment 4
[0074] 200 g of commercially available tungsten powder (ungranulated powder) with an average particle diameter of 0.5 μm was thrown into 400 g of water in which 10% by mass of ammonium persulfate was dissolved, and the surface layer of tungsten was oxidized by stirring sufficiently with a homogenizer. After washing with water, 500 mL of 2N aqueous sodium hydroxide solution was added and stirred to remove oxides on the surface layer. Repeat the series of operations of oxidation and oxide removal three times, and put the tungsten powder with a volume average particle size of 0.2 μm into an ethanol solution of 0.15% by mass of ammonium phosphomolybdate and mix well, then put it into vacuum drying The ethanol was removed by machine at 60°C and dried. Then pair the 5 x 10 -3 Elemental analysis of the granulated powder obtained by firing and reacting at 1370°C for 20 minutes under a vacuum condition of Pa showed that the molybdenum element content was 0.058% by mass, the phosphorus...
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