Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Post sintering operation
Patent
1994-08-29
1998-03-31
Jenkins, Daniel J.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Post sintering operation
419 33, 419 38, 75369, 75623, B22F 100, B22F 312, B22F 922
Patent
active
057349606
ABSTRACT:
A process for producing potassium and silicon doped molybdenum (KS molybdenum). The process involves mixing an aqueous ammonium molybdate solution and a dilute aqueous potassium silicate solution. The molybdate solution has a pH and a specific gravity sufficient to promote formation of diammonium molybdate crystals in the mixture. Preferably, the pH is about 8.8-11.0 and the specific gravity is about 1.20-1.32. The amount of potassium silicate and the amount of potassium silicate solution are selected to provide predetermined amounts of potassium and silicon in the mixture, preferably about 800-1300 ppm potassium and about 500-1100 ppm silicon, both amounts based on the amount of molybdenum. The mixture is heated to aid dissolution of the potassium silicate and ammonium molybdate in said mixture and to produce a homogeneous solution of ammonium molybdate, potassium, and silicon. The ammonium dimolybdate doped with potassium and silicon is then crystallized out of solution and calcined, for example in an atmosphere of dissociated ammonia, to produce molybdenum dioxide doped with potassium and silicon. The doped molybdenum dioxide is reduced, for example in a flowing hydrogen atmosphere, to produce a doped molybdenum powder, which then may be pressed and sintered to full density.
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Carr, Jr. Vernon L.
Cheresnowsky Michael J.
Christini James N.
Miller Michael J.
Patrician Thomas J.
Clark Robert F.
Jenkins Daniel J.
Osram Sylvania Inc.
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