Metal powders produced by the reduction of the oxides with gaseous magnesium
AssigneeH.C. Starck GmbH
InventorsLeonid N. Shekhter, Terrance B. Tripp, Leonid L. Lanin, Karlheinz Reichert, Oliver Thomas, Joachim Vieregge
Life of this patent
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Abstract
Metal powder Ta and/or Nb, with or without one or metals from the group Ta, Nb, Ti, Mo, W, V, Zr and Hf, is made in a fine powder form by reduction of metal oxide by contact with a gaseous reducing agent, preferably an alkaline earth metal, to near complete reduction, leaching, further deoxidation and agglomeration, the powder so produced being sinterable to capacitor anode form and processable to other usages.
Claims66
Niobium powder in the form of agglomerated primary particles with a particle size of 100 to 1000 nm, wherein the agglomerates have a particle size corresponding to D10=3 to 80 μm, D50=20 to 250 μm and D90 30 to 400 μm as determined by Mastersizer.
An alloy powder for use in the manufacture of electrolyte capacitors consisting essentially of niobium and containing up to 40 at.-% of tantalum based on the total content of Nb and Ta.
A process for making a metal powder selected from the group consisting of Ta, Nb, Ta alloys, Nb alloys, and combinations thereof, alone or with one or more of metals selected from the group consisting of Ti, Mo, W, Hf and V and Zr,
- wherein the process comprises:
- (a) providing an oxide or mixed oxides of the metal(s), wherein the oxide or the mixed oxides are in a form that is traversable by gas,
- (b) passing a hydrogen-containing gas through an oxide mass at an elevated temperature at a first stage and removing at least 20% of the oxygen contained in the oxide mass, thereby reducing the oxide or mixed oxides to a suboxide, and
- (c) reducing the suboxide in a second stage with a reducing agent selected from the group of reducing metals and hydrides of reducing metals, and thereby freeing metal from the suboxide and forming a primary metal powder.
A single-stage process for making a metal powder selected from the group consisting of Ta and Nb, and one or more metals selected from the group consisting of Ti, Mo, W, Hf, V and Zr,
- the process comprising:
- (a) providing an oxide or mixed oxides of the metal(s), wherein the oxide or the mixed oxides are in a form that is traversable by gas,
- (b) generating a gaseous reducing agent at a site outside an oxide mass and passing the gas through the mass at a first temperature, and
- (c) reducing of the oxide(s) at a second temperature and freeing metal portion from the oxide, wherein the first temperature is the same or less than the second temperature.
A capacitor anode comprising a sintered niobium powder agglomerated primary particles with a particle size ranging from 100 to 1000 nm, wherein the agglomerated primary particles have a particle size ranging from D10=3 to 80 μm, D50=20 to 250 μm and D90 30 to 400 μm as determined by Mastersizer.
An alloy powder for use in the manufacture of electrolyte capacitors comprising niobium and containing up to 40 atomic % of tantalum based on the total content of Nb and Ta.
A process for the manufacture of alloy powder for use in the manufacture of electrolyte capacitors comprising niobium and containing up to 40 atomic % of tantalum based on total content of Nb and Ta comprising:
- (a) hydriding an electron-beam melted alloy ingot containing Nb and up to 40 atomic % Ta based on the total content of Nb and Ta,
- (b) comminuting said hydrided alloy ingot,
- (c) dehydriding the comminuted alloy obtained from step (b), and
- (d) forming said comminuted alloy into flakes,
- (e) agglomerating said flakes at a temperature of 880 to 1150° C. in the presence of an alkali earth metal as a reducing agent, and
- (f) leaching and washing the agglomerated alloy flakes to remove any residual and residual product of the reducing agent.
Dependencies are inferred from the claim text.