US3716357A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of thoriated nickel-chromium alloy powder
Assignee: Viridian Inc Canada
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Filing: 1969-04-03
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Granted: 1973-02-13
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Expires: 1989-04-03
Abstract
Abstract Nickel-chromium alloy powder containing dispersed refractory oxide particles is produced by heating nickel powder particles containing physically inseparable sub-micron refractory oxide particles, a major portion of which are fixed in the surfaces of the nickel particles, in contact with a chromium source material, such as chromium powder or chromium oxide, in a flowing atmosphere of pure dry hydrogen at an elevated temperature and for a time sufficient to effect diffusion of chromium into the nickel particles and to reduce excess oxygen to an acceptable level.
Inventors
- 👤 D Evans
- 👤 D Fustakian
- 👤 L Norris
- 👤 R Fraser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:23
CPC Classifications
C; C22; C22C; C22C32/00; C22C32/001; C22C32/0015; C22C32/0026; Y; Y10; Y10S; Y10S75/00; Y10S75/956
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
172 words
The process for producing refractory oxide containing nickel-chromium alloy powders which comprises: a. providing nickel powder particles containing uniformly dispersed sub-micron refractory oxide particles at least a portion of which are fixed on the surfaces of said nickel particles; b. forming a mixture of said nickel particles and a finely divided chromium source material selected from the group consisting essentially of chromium metal, chromium oxide, chromium hydroxide and mixtures thereof; c. forming a loose bed of the resulting powder mixture and heating said bed at a temperature above about 1,200*F. but below the sintering temperature of said mixture in a flowing atmosphere of hydrogen having a dew point below about - 4* F. d. continuing said heating for a time sufficient to effect diffusion of substantially all available chromium into the nickel particles and to reduce the amount of oxygen in the powder mixture to less than 0.60 percent oxygen in excess of the oxygen contained in the refractory oxide; and e. recovering the resulting refractory oxide containing nickel-chromium alloy powder product.
Claim 2
Dependent Claim
172 words
The process for producing refractory oxide containing nickel-chromium alloy powders which comprises: a. providing nickel powder particles containing uniformly dispersed sub-micron refractory oxide particles at least a portion of which are fixed on the surfaces of said nickel particles; b. forming a mixture of said nickel particles and a finely divided chromium source material selected from the group consisting essentially of chromium metal, chromium oxide, chromium hydroxide and mixtures thereof; c. forming a loose bed of the resulting powder mixture and heating said bed at a temperature above about 1,200*F. but below the sintering temperature of said mixture in a flowing atmosphere of hydrogen having a dew point below about - 4* F. d. continuing said heating for a time sufficient to effect diffusion of substantially all available chromium into the nickel particles and to reduce the amount of oxygen in the powder mixture to less than 0.60 percent oxygen in excess of the oxygen contained in the refractory oxide; and e. recovering the resulting refractory oxide containing nickel-chromium alloy powder product.
Claim 3
Dependent Claim
61 words
The process according to claim 1 wherein said bed is heated at a temperature, Tcm not greater than -19.4/(f + 0.028) + Tm degrees Kelvin, where f is the volume fraction of refractory oxide contained in the nickel powder particles and Tm is the melting temperature of the final nickel-chromium alloy product the volume fraction, f, being between 0.005 and 0.25.
Claim 4
Dependent Claim
20 words
The process according to claim 2 wherein the heating temperature is from about 50*F. to about 300* F. below Tcm.
Claim 5
Dependent Claim
21 words
The process according to claim 2 wherein the powder mixture contains from about 16 to about 21 percent by weight chromium.
Claim 6
Dependent Claim
43 words
The process according to claim 1 wherein nickel powder particles are provided which contain thoria particles within the size range of about 2 to about 50 millimicrons, a major portion of which are fixed in and uniformly distributed over the nickel particle surfaces.
Claim 7
Dependent Claim
27 words
The process according to claim 5 wherein said nickel powder particles are obtained by direct hydrogen reduction of an aqueous suspension of thoria impregnated basic nickel compounds.
Claim 8
Dependent Claim
25 words
The process according to claim 2 wherein the chromium source material is high purity chromium powder having a partIcle size up to about 50 microns.
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) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |