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AssigneeHermann C. Starck Berlin
InventorsWolf-Wigand Albrecht, Uwe Papp
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A process for the production of agglomerated valve metal powder which comprises heating an admixture of a valve metal powder and a reducing agent in the presence of an inert gas or under high vacuum for a sufficient time and at a sufficiently elevated temperature that agglomeration of the valve metal powder occurs, and removing the reaction products of the reducing agent and the valve metal and any unreacted reducing agent from the agglomerated valve metal powder by subsequent reaction with an inorganic acid. The agglomerated powder can be sintered to prepare valve metal electrodes, e.g., anodes, which can also be prepared by direct sintering of the admixture of the metal powder and the reducing agent.
A process for the production of agglomerated tantalum powder, said tantalum being essentially pure and designed for use in an anode for an electrolytic capacitor with high specific charge and low leakage current, which comprises heating individual particles of said tantalum admixed with solid particles of a metallic reducing agent in the presence of an inert gas or under high vacuum at a temperature range of about 800.degree. C. to about 1200.degree. C. for a sufficient time that agglomeration of the tantalum powder occurs, and removing the reaction products of the reducing agent and the tantalum and any unreacted reducing agent from the agglomerated tantalum powder by subsequent reaction with an inorganic acid, said metallic reducing agent being selected from the group consisting of aluminum, calcium and magnesium.
Dependencies are inferred from the claim text.