Method for making a porous tantalum pellet
AssigneeSprague Electric Company
InventorWalter J. Bernard
Life of this patent
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Abstract
A quantity of tantalum powder is heated to a temperature greater than 400.degree. C in a non-oxidizing atmosphere to dissolve the tantalum oxide film existing on the surfaces of the tantalum particles. The treated powder without conventional organic binders is compressed to form a unitary pellet in a mold maintained in an inert atmosphere. The pellet is subsequently heated in a vacuum to sinter the particles together and to provide a porous tantalum pellet having carbon-free tantalum surfaces and a large exposed surface area per unit weight of tantalum. Electrolytic capacitors made from these pellets exhibit a larger CV product per unit weight of tantalum and/or a lower leakage current than for comparable capacitors known heretofore.
Claims17
A method for making a porous tantalum pellet comprising the sequential steps of:
- a. heating a quantity of tantalum powder particles having a surface oxide to a temperature greater than 400.degree. C and no greater than 1200.degree. C in a non-oxidizing atmosphere to dissolve said surface oxide into the bulk of said particles;
- b. dispensing said powder into a molding press cavity;
- c. providing a protective atmosphere for said powder from said heating through said dispensing;
- d. compressing said powder in said cavity to provide a porous tantalum pellet;
- and
- e. vacuum firing said pellet to sinter said compressed particles to each other.
Dependencies are inferred from the claim text.