US3615307A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing alpha-alumina crystals from aluminum oxide containing calcium oxide
Assignee: Saint Gobain Abrasives Inc
•
Filing: 1967-10-19
•
Granted: 1971-10-26
•
Expires: 1987-10-19
Abstract
Abstract Abrasive sized crystalline alpha alumina crystals are produced from A12O3 containing powder by heating alumina source with source of soda and Titania to 1475 to 1700* C., with crystallization taking place above 1475* C. in presence of atmosphere which is reducing with respect to soda. The addition of combined calcium to the mix, in the amount of at least 0.5 percent by weight calculated as CaO, produces larger sized crystals.
Inventors
- 👤 Cecil M Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:04
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/021; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C01P; C01P2004/00; C01P2004/20; C01P2004/54; C01P2004/60; C01P2004/61; C01P2004/62; C01P2006/00; C01P2006/11; C01P2006/14; C01P2006/21
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
17 words
heating said composition within a temperature range from about 1450* C. to the melting temperature of alpha-alumina;
Claim 2
Dependent Claim
25 words
A method as in claim 1 in which the combined calcium is present in the amount of from 0.5 to 3 percent, calculated as CaO.
Claim 3
Dependent Claim
33 words
A method as in claim 1 in which the combined calcium source is selected from the group consisting of lime, calcium carbonate, calcium hydroxide, calcium sulfate, calcium chloride, calcium oxalate, and calcium cyanamide.
Claim 4
Dependent Claim
35 words
holding said composition at a temperature within said temperature range for from 1-6 hours under conditions whereby more than 95 percent of the soda content is removed from the reaction mix in from 1-6 hours,
Claim 5
Dependent Claim
11 words
cooling the reaction mix and separating abrasive sized alpha-alumina crystals therefrom,
Claim 6
Dependent Claim
25 words
the improvement consisting of adding to the mix a calcium containing material in the amount of at least 0.5 percent by weight, calculated as CaO.
References Cited (Backward Citations)
US2369709A
Cited
US2046764A
Cited
US2587328A
Cited
US2725286A
Cited
US2961296A
Cited
US3079243A
Cited
US3216794A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-25 | 1975-04-26 | 1975-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-25 | 1979-04-26 | 1979-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-25 | 1983-04-26 | 1983-10-26 | $7700.00 | Window Closed / Lapsed |