Hermann C. Starck Berlin

Bayer Aktiengesellschaft

Starck Vtech Ltd.

Dieter Behrens

Reinhard Hahn

Wolf-Wigand Albrecht

Uwe Papp

Tadashi Komeya

Katsuo Iwabuchi

Hiroshi Oki

Tantalum powder obtained by adding magnesium powder to tantalum powder which is prepared by reducing potassium tantalum fluoride with sodium metal, without conventional heat-treatment for agglomeration, to remove oxygen present in the tantalum powder, then washing with an acid and drying; an anode body for electrolytic capacitors produced by sintering the tantalum powder; and, an electrolytic capacitor which comprises the anode body incorporated therein. The tantalum powder has a large specific surface area and accordingly, the electrolytic capacitor in which the anode body produced from the tantalum powder is incorporated has an extra high capacity, i.e., a CV ranging from 70000 to 80000. The probability of causing ignition during the production process is substantially reduced and thus the tantalum powder can be handled with safety.

Tantalum powder and electrolytic capacitor using same

Earth acid metal powders, such as tantalum or niobium, useful in the production of electrolytic capacitors and other electronic components, are agglomerates of sintered compacts, wherein the mean grain size of the agglomerates is no more than 2.0 .mu.m, determined by the Fisher Sub-Sieve Sizer, and wherein the agglomerates consist of primary individual agglomerated particles of mean grain size of no more than 0.7 .mu.m.

Fine-grained, high-purity earth acid metal powders, a process for their

A process for the production of valve metal powder, which is doped with boron or boron compounds, for electrolytic capacitors having a low relative leakage current and a high specific charge. The doping with boron or boron compounds in amounts of up to 0.5 percent by weight, relative to the metal content, can take place either during the production of the metal powder or the green valve metal anodes.

Valve metal powder doped with boron

An electrode having an electrical capacitance in excess of 10,000 .mu.C/g prepared by sintering a tantalum powder having a grain size finer than 2.5 .mu.m, and the process of preparation.

Electrodes of sintered tantalum powder of fine grain size and process of

An anhydrous mixture of extrudable viscosity of an activated alkali metal tantalum or niobium halide powder, an alkali metal halide powder, and a molten alkali metal in about 1:0.75-2.0:4.75-5.5 molar ratio is formed into a paste which is extruded and formed into masses of critical dimensions and temperature. The mass is ignited and a self-sustaining reduction reaction ensues. The reaction product is powdered, washed and dried. The product is pure tantalum or niobium powder in almost quantitative yield. The powder is specially suited for use as electrolytic capacitor anodes. The powder is improved by passage through a plasma of an inert gas. The process can be performed on a continuous scale.

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Goslar, Germany

Dieter Behrens