A method for producing agglomerated tantalum particles, comprising: a step for grinding secondary tantalum particles, which are obtained by reducing a tantalum salt, and adding water thereto to give a water-containing mass; a step for drying said water-containing mass to give a dry mass; a step for sieving said dry mass to give spherical particles; and a step for heating said spherical particles. A mixed tantalum powder comprising a mixture of agglomerated tantalum particles (X) with agglomerated tantalum particles (Y), wherein said agglomerated tantalum particles (X) show a cumulative percentage of particles with particle size of 3 μm or less of 5 mass % or less after 25 W ultrasonic radiation for 10 min, while said agglomerated tantalum particles (Y) show a cumulative percentage of particles with particle size of 3 μm or less of 10 mass % or more after 25 W ultrasonic radiation for 10 min.

A porous aluminum electrode has a porous layer formed by sintering aluminum powder on the surface of an aluminum core. The porous aluminum electrode, when subjected to a formation to a voltage of 200V or more, is boiled and then subjected to a first forming process in which formation is performed in an aqueous solution of ammonium adipate at a temperature of 80° C. or below and a second forming process in which formation is performed in a boric acid aqueous solution. When heat depolarization is first carried out, washing with water is performed for five minutes or more before heat depolarization; therefore, the porous layer is not destroyed.

A method for finely powdering tungsten powder, which includes: a process for classifying a material tungsten powder into a fine powder having a relatively small average particle diameter and a coarse powder having a relatively large average particle diameter; an oxidation process for forming an oxide film on the particle surface of the coarse powder; and an alkali treatment process for removing the oxide film formed in the oxidation process and a natural oxide film formed on the fine powder with an alkali aqueous solution. Also disclosed is a method for producing ultrafine tungsten powder, which includes obtaining tungsten powder having an average particle diameter of 0.04 to 0.4 μm and a BET specific surface area of 5 to 15 m.sup.2/g by the above method for finely powdering.

A solid electrolytic capacitor that contains an anode body, dielectric overlying the anode body, adhesion coating overlying the dielectric, and solid electrolyte overlying the adhesion coating. The solid electrolyte contains an inner conductive polymer layer and outer conductive polymer layer, at least one of which is formed from a plurality of pre-polymerized conductive polymer particles. Furthermore, the adhesion coating contains a discontinuous precoat layer containing a plurality of discrete nanoprojections of a manganese oxide (e.g., manganese dioxide).

An anode for use in a high voltage electrolytic capacitor is provided. The anode contains a sintered porous pellet and a leadwire extending therefrom in a longitudinal direction. The pellet is multi-layered to the extent that it contains at least a first layer positioned adjacent to a second layer, both of which extend along the length of the anode. The anode leadwire is embedded within the first layer. For this reason, the first layer has a thickness greater than that of the leadwire. Nevertheless, the use of a separate and distinct second layer adjacent to the first layer can allow each of the layers to be independently pressed using a multi-sided compaction device so that the properties of the anode are not significantly impacted by the presence of the relatively large anode leadwire.

A catalyst-free synthesis method for the formation of a metalorganic compound comprising a desired (first) metal may include, for example, selecting another (second) metal and an organic solvent, with the second metal being selected to (i) be more reactive with respect to the organic solvent than the first metal and (ii) form, upon exposure of the second metal to the organic solvent, a reaction by-product that is more soluble in the organic solvent than the metalorganic compound. An alloy comprising the first metal and the second metal may be first produced (e.g., formed or otherwise obtained) and then treated with the organic solvent in a liquid phase or a vapor phase to form a mixture comprising (i) the reaction by-product comprising the second metal and (ii) the metalorganic compound comprising the first metal. The metalorganic compound may then be separated from the mixture in the form of a solid.

The invention relates to the rare metal smelting field, and particularly, the present invention relates to a tantalum powder for preparing capacitors and a process for preparing the tantalum powder, and to a sintered anode prepared from the tantalum powder. As to the tantalum powder as provided by the invention, its primary tantalum powder has a BET of from 3.0 to 4.5 m.sup.2/g. After the secondary agglomeration, the tantalum powder has a large particle size. The tantalum powder has an average Fisher sub-sieve size (FSSS) of 1.2 to 3.0 μm wherein as measured with a standard sieve mesh, more than 75% of tantalum powder has a +325-mesh, and a particle size distribution D50 of more than 60 μm, that is, the secondary particle size is high. A resultant capacitor anode prepared by sintering the tantalum powder of the invention at 1200° C. for 20 minutes and then being energized at the voltage of 20 V has the specific capacitance of from 140,000 to 180,000 μFV/g and the residual current of less than 1.0 nA/μFV. Meantime, the invention provides an economical process for making the tantalum powder.

An electrolytic capacitor includes a capacitor element that includes an anode body that has a porous structure, a dielectric layer disposed on a surface of the anode body, and a solid electrolyte layer that covers at least a part of the dielectric layer. The anode body contains a first group metal including at least one selected from the group consisting of tantalum, niobium, titanium, aluminum, and zirconium. The dielectric layer contains an oxide of the first group metal and a second group metal including at least one selected from the group consisting of iron, chromium, copper, silicon, molybdenum, sodium, and nickel. A ratio X of a total number of atoms of the second group metal to a total number of atoms of the first group metal in the dielectric layer is equal to or less than 100 ppm.

A module containing a plurality of active capacitors and a sacrificial capacitor is provided. The active capacitors and sacrificial capacitor are aligned along a horizontal direction so that the side surfaces of their cases are parallel to each other. The particular arrangement of the active capacitors and sacrificial capacitor results in a module configuration where the anode terminations for the active capacitors and an external component of the lead frame for the sacrificial capacitor are coplanar so that the module can be mounted to a circuit board via the anode terminations and the external component of the lead frame in a mechanically and electrically stable manner. Further, the center of gravity of the module in the length and/or width directions can be located at a midpoint of the overall module length and/or width, which enhances the stability of the module when mounted to a circuit board.

A method for preparing a tantalum power of capacitor grade, comprising: solid tantalum nitride is added when potassium fluotantalate is reduced by sodium. The method increases the nitrogen content in the tantalum powder, and at the same time improves the electrical performance of the tantalum powder. The specific capacitance is increased, and the leakage current and loss is improved. The qualification rate of the anode and the capacitor product is also improved. The method is characterized in that the nitrogen in the tantalum nitride diffuses between the particles of the tantalum powder, with substantially no loss, and thus the nitrogen content is accurate and controllable.