Hermann C. Starck Berlin

Rudiger Wolf

Wolf-Wigand Albrecht

Uwe Papp

Axel Hoppe

The invention relates to an improvement of the flowability and an increase in the bulk density of high-surface area valve metal powders by means of the addition of finely divided extraneous metal oxides in quantities of up to 5000 ppm, relative to the quantity of metal, before the powder-metallurgical processing of the valve metal powder.

Process for improving the flowability and increasing the bulk density of

The invention relates to a process for treating the surface of valve metals, in particular niobium and tantalum, in the form of agglomerated or non-agglomerated powders, thin foils or molded articles prepared from powder, for use as electrolytic capacitor electrodes, these metals being heated in at least one stage to temperatures of 300.degree. to 2,000.degree. C. under a high vacuum or an inert gas atmosphere and in the presence of chalcogens or chalcogen compounds, excluding oxygen.

Process for treating the surface of valve metals with chalcogens

To produce valve-metal anodes for electrolytic capacitors, reducing agents are added to the already sintered and/or unsintered anode bodies to improve the electrical properties, whereupon heating is carried out at temperatures above the melting point of the reducing agents and below the temperatures conventionally used for sintering the valve-metal anodes.

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Vienenburg, Germany

Rudiger Wolf