Method for the production of niobium and tantalum powder
View Patent ↗Process for the production of valve metal powders, in particular niobium and tantalum powder, by reduction of corresponding valve metal oxide powders by means of vaporous reducing metals and/or hydrides thereof, preferably in the presence of an inert carrier gas, wherein the reduction is performed at a vapor partial pressure of the reducing metal/metal hydride of 5 to 110 hPa and an overall pressure of less than 1000 hPa, and tantalum powder obtainable in this way having a high stability of the powder agglomerate particles.
1. Tantalum powder having a specific surface area of 0.9 to 6 m 2 /g, which displays an agglomerate stability, measured as the quotient of the D50 value according to ASTM B 822 and the D50 US value measured after ultrasonic treatment, of less than 2, wherein the powder consists of agglomerates having a particle size distribution with a D10 value of 5 to 30 μm, a D50 value of 20 to 100 μm and a D90 value of 40 to 250 μm according to ASTM B 822 wherein the ultrasonic treatment is performed by using an ultrasonic power which is introduced with an ultrasonic generator while stirring.
2. Tantalum powder according to claim 1 having a specific surface area of 1.5 to 2 m 2 /g and an agglomerate stability value D50/D50 US of less than 1.7.
3. The powder as claimed in claim 2 , wherein the powder has primary structures of agglomerates having an average smallest dimension of 0.15 to 0.8 μm.
4. Tantalum powder according to claim 1 having a specific surface area of 2.7 to 3.3 m 2 /g and an agglomerate stability value D50/D50 US of less than 1.7.
5. The powder as claimed in claim 4 , wherein the powder has primary structures of agglomerates having an average smallest dimension of 0.15 to 0.8 μm.
6. Tantalum powder according to claim 1 , wherein the quotient of the D50 value according to ASTM B 822 and the D50 US value measured after ultrasonic treatment, of less than 1.7.
7. Tantalum powder according to claim 1 , wherein the quotient of the D50 value according to ASTM B 822 and the D50 US value measured after ultrasonic treatment, of less than 1.5.
8. The powder as claimed in claim 7 , wherein the powder has primary structures of agglomerates having an average smallest dimension of 0.15 to 0.8 μm.
9. The powder as claimed in claim 7 , wherein the powder has a specific surface area of 0.9 to 4 m 2 /g.
10. The powder as claimed in claim 9 , wherein the powder has primary structures of agglomerates having an average smallest dimension of 0.15 to 0.8 μm.
11. The powder as claimed in claim 1 , wherein the powder has primary structures of agglomerates having an average smallest dimension of 0.15 to 0.8 μm.