US4101309A
Expired / Lapsed
US
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Method for preparing tungsten materials
Assignee: Toshiba Corp
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Filing: 1976-10-13
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Granted: 1978-07-18
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Expires: 1996-10-13
Abstract
Abstract A method for preparing tungsten materials in which tungsten powder obtained by reducing tungsten oxides having doping agents added thereto is washed first with hydrochloric acid having a concentration of not lower than 4% by weight and then with hydrofluoric acid having a concentration of not lower than 3% by weight, and thereafter dried. The above-mentioned washing steps may be carried out at a time by using a mixture of such hydrochloric acid and hydrofluoric acid as specified above. Articles formed by treating tungsten materials obtained by the above-mentioned process are subjected to only a low high temperature deformation.
Inventors
- 👤 Isamu Koseki
- 👤 Motoo Seimiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:28
CPC Classifications
C; C22; C22C; C22C1/00; C22C1/10; C22C1/1089; C22B; C22B34/00; C22B34/30; C22B34/36
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
86 words
In a method for preparing a tungsten material comprising the steps of reducing tungsten oxides having doping agents added thereto, washing the resulting tungsten powder with an acid, and thereafter drying the washed tungsten powder, the improvement comprising conducting said washing step separately with hydrochloric acid and then with hydrofluoric acid by first washing said tungsten powder with hydrochloric acid having a concentration of not less than 4% by weight and thereafter washing with hydrofluoric acid having a concentration of not less than 3% by weight.
Claim 2
Dependent Claim
86 words
In a method for preparing a tungsten material comprising the steps of reducing tungsten oxides having doping agents added thereto, washing the resulting tungsten powder with an acid, and thereafter drying the washed tungsten powder, the improvement comprising conducting said washing step separately with hydrochloric acid and then with hydrofluoric acid by first washing said tungsten powder with hydrochloric acid having a concentration of not less than 4% by weight and thereafter washing with hydrofluoric acid having a concentration of not less than 3% by weight.
Claim 3
Dependent Claim
35 words
The method according to claim 1 in which said hydrochloric acid has a concentration of from 4 to 12% by weight and said hydrofluoric acid has a concentration of from 3 to 15% by weight.
Claim 4
Dependent Claim
31 words
The method according to claim 2 in which said hydrochloric acid concentration is from 4 to 7% by weight and said hydrofluoric acid concentration is from 3 to 6% by weight.
Claim 5
Dependent Claim
89 words
In a method for preparing a tungsten material including the steps of (a) reducing tungsten oxides having doping agents added thereto, (b) washing the resulting tungsten powder with an acid, and thereafter (c) drying the washed tungsten powder, the improvement consisting of conducting the washing step separately with hydrochloric acid and then with hydrofluoric acid by first washing with: (1) hydrochloric acid having a concentration of from 4 to 12% by weight, and thereafter washing with (2) hydrofluoric acid having a concentration of from 3 to 15% by weight.
Claim 6
Dependent Claim
89 words
In a method for preparing a tungsten material including the steps of (a) reducing tungsten oxides having doping agents added thereto, (b) washing the resulting tungsten powder with an acid, and thereafter (c) drying the washed tungsten powder, the improvement consisting of conducting the washing step separately with hydrochloric acid and then with hydrofluoric acid by first washing with: (1) hydrochloric acid having a concentration of from 4 to 12% by weight, and thereafter washing with (2) hydrofluoric acid having a concentration of from 3 to 15% by weight.
Claim 7
Dependent Claim
31 words
The method according to claim 4 in which said hydrochloric acid concentration is from 4 to 7% by weight and said hydrofluoric acid concentration is from 3 to 6% by weight.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-17 | 1982-01-16 | 1982-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-17 | 1986-01-16 | 1986-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-17 | 1990-01-16 | 1990-07-18 | $7700.00 | Window Closed / Lapsed |