US3635693A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing tantalum or niobium powder from compact bodies
Assignee: H.C. Starck GmbH
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Filing: 1969-01-27
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Granted: 1972-01-18
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Expires: 1989-01-27
Abstract
Abstract A block of tantalum or niobium is first stripped of superficial impurities by immersion in an acid bath, for instance hydrofluoric acid. Thence it is dried in a vacuum and saturated with hydrogen under high pressure and heat. This embrittles the body which is fragmented into coarse metal-hydride particles. The brittle fragments are crushed to a powder of the desired fineness and the powder is cleaned in boiling acid then degassed in a vacuum under heat to transform the interstitial hydride to the pure-metal powder.
Inventors
- 👤 Hans Joachim Friedrich
- 👤 Horst Meyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:58
CPC Classifications
C; C22; C22C; C22C1/00; C22C1/10; C22C1/1026; C01; C01B; C01B6/00
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
28 words
The method defined in claim 1 wherein said body is etched for 24 to 48 hours in aqueous hydrofluoric acid at a concentration of at least 40 percent.
Claim 2
Dependent Claim
31 words
The method defined in claim 2 wherein the hydrofluoric acid is removed by washing with water, further comprising the step of drying the washed body prior to saturating same with hydrogen.
Claim 3
Dependent Claim
12 words
The method defined in claim 1 wherein the body is heated inductively.
Claim 4
Dependent Claim
301 words
The method defined in claim 1 wherein said bar is stripped by treating it with agitation for a period of about 24 hours with a 40 percent solution of hydrofluoric acid, and washing the bar thereafter with distilled water until the wash water assumes a neutral character; said is subjected while its surface remains damp from the washing thereof to a vacuum of better than 10 4 Torr. in an induction furnace until the vacuum is maintained at that level for at least 1 hour; heating said bar inductively in said vacuum to a temperature of at least 1,200* C. until the pressure at this temperature remains constant for at least 1 hour at 10 4 Torr; thereafter reducing the temperature of said bar to a temperature in the range of 600* to 1,00* C. and exposing said bar to hydrogen at a pressure of about 400 Torr; upon a decrease in the pressure in said furnace by about 25 percent by absorption of hydrogen interstitially by said bar, increasing the pressure of hydrogen in said furnace again to at least 400 Torr until the bar is saturated with hydrogen at said temperature in said range of 600* to 1,000* C.; thereafter lowering the temperature of said bar to substantially 200* to 500* C. and saturating said bar at the latter temperature at 300 to 400 Torr pressure with hydrogen; thereafter lowering the temperature of the bar to 60* to 120* C. and saturating the bar at this latter temperature at 300 to 400 Torr pressure with hydrogen; evacuating hydrogen from said furnace and recovering said coarse metal-hydride powder therefrom; comminuting the coarse metal-hydride powder to a maximum particle size of about 150 microns; and subjecting the comminuted product to high vacuum at a temperature of about 600* to 1,200* C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |