Specialized metallurgical processes – compositions for use therei – Compositions – Loose particulate mixture containing metal particles
Patent
1996-04-25
1999-09-21
Jenkins, Daniel J.
Specialized metallurgical processes, compositions for use therei
Compositions
Loose particulate mixture containing metal particles
75622, 419 33, B22F 100
Patent
active
059548568
ABSTRACT:
A process for sizing (i.e., comminuting) a tantalum powder including agglomerates of smaller particles, which process yields a tantalum powder having an as-comminuted agglomerate size distribution with the product of the Volume Mean Diameter, MV (in microns as measured by light scattering techniques such as Microtrac analysis), times specific surface area, BET (m.sup.2 /g), being less than about 25. These powders after sizing typically have ratios of Scott Bulk Density : BET Surface Area in the range from about 20 to about 35. Also provided are powders having a substantially unimodal and narrow agglomerate size distribution in all stages of production, namely after sizing (i.e., deagglomeration by comminution), thermal agglomeration (i.e., heat treatment), and deoxidation. These resultant powders have high surface area and good flowability properties and, upon sintering, exhibit controlled shrinkage with high porosity. Further provided are sized heat treated tantalum powders having agglomerate particle sizes wherein the product of the Volume Mean Diameter, MV, times the specific surface area, BET, is in the range from about 90 to about 250. Sized and agglomerated powders which are deoxidized are also provided wherein the product of the Volume Mean Diameter, MV, times the specific surface area, BET, is in the range from about 90 to about 250.
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Chang Hongju
Fife James Allen
Pathare Viren M.
Rao Bhamidipaty K. D. P.
Ruch Lee M.
Cabot Corporation
Jenkins Daniel J.
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