Patent US4643983A successfully refreshed from Google Patents.
US4643983A
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Method of producing a grinding medium
Assignee: Individual
•
Filing: 1985-07-23
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Granted: 1987-02-17
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Expires: 2005-07-23
Abstract
Abstract A method of producing a grinding medium on the basis of alpha-alumina and at least one alumina carbide selected from the group consisting of Al 2 OC and Al 4 O 4 C comprises the steps of melting a mixture of alumina or a material rich in alumina with a carbon-containing reducing agent to obtain a melt, rapidly cooling the melt to obtain a solidified body, breaking the solidified body into abrasive grains, and subjecting the abrasive grains to a heat treatment at a temperature of 500° C. and 1500° C. for a period of three minutes to 24 hours.
Inventors
- 👤 Hans Zeiringer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:25
CPC Classifications
C; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C09K3/1427
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
142 words
A method of producing a grinding medium consisting essentially of alpha-alumina, Al 2 OC and Al 4 O 4 C, which comprises the steps of (a) melting a mixture of a raw material selected from the group consisting of alumina and a material rich in alumina with a carbon-containing reducing agent to obtain a melt, (b) cooling the melt at a speed of more than 100° C. per minute to obtain a solidified body, (c) breaking the solidified body into abrasive grains, and (d) subjecting the abrasive grains to a heat treatment at a temperature of between 500° C. and 1500° C. for a period of three minutes to 24 hours until their Al 4 C 3 -content is less than 5%, by weight, said heat treatment being limited to a maximum period of ten minutes when said temperature is 1500° C.
Claim 2
Independent Claim
142 words
A method of producing a grinding medium consisting essentially of alpha-alumina, Al 2 OC and Al 4 O 4 C, which comprises the steps of (a) melting a mixture of a raw material selected from the group consisting of alumina and a material rich in alumina with a carbon-containing reducing agent to obtain a melt, (b) cooling the melt at a speed of more than 100° C. per minute to obtain a solidified body, (c) breaking the solidified body into abrasive grains, and (d) subjecting the abrasive grains to a heat treatment at a temperature of between 500° C. and 1500° C. for a period of three minutes to 24 hours until their Al 4 C 3 -content is less than 5%, by weight, said heat treatment being limited to a maximum period of ten minutes when said temperature is 1500° C.
Claim 3
Dependent Claim
14 words
The method of claim 1, wherein the mixture further comprises a metallic reducing agent.
Claim 4
Dependent Claim
20 words
The method of claim 2, wherein the metallic reducing agent is selected from the group consisting of magnesium and aluminum.
Claim 5
Dependent Claim
38 words
The method of claim 1, further comprising the step of adding to the mixture 0.1-10%, by weight, of at least one additive selected from the group consisting of magnesium, calcium, zirconium, titanium, silicon, chromium and a rare earth.
Claim 6
Dependent Claim
28 words
The method of claim 1, wherein the abrasive grains are surface-coated with at least one substance selected from the group consisting of silicates, pulverulent corundum, and iron oxides.
Claim 7
Dependent Claim
15 words
The method of claim 5, wherein the abrasive grains are surface-coated before the heat treatment.
Claim 8
Dependent Claim
15 words
The method of claim 5, wherein the abrasive grains are surface-coated after the heat treatment.
Claim 9
Dependent Claim
32 words
The method of claim 1, wherein the abrasive grains are subjected to the heat treatment at a temperature between 1000° C. and 1300° C. for a period of 5 to 60 minutes.
Claim 10
Dependent Claim
25 words
The method of claim 1, wherein the carbon-containing reducing agent is selected from the group consisting of coke, carbon black, graphite, anthracite and amorphous carbon.
Claim 11
Dependent Claim
13 words
The method of claim 1, wherein the carbon-containing reducing agent is a carbide.
Claim 12
Dependent Claim
14 words
The method of claim 10, wherein the carbide is Al 4 C 3 .
Claim 13
Dependent Claim
18 words
The method of claim 1, wherein the Al 4 C 3 -content is less than 0.5%, by weight.
Claim 14
Dependent Claim
19 words
The method of claim 1, wherein the carbon content of the mixture is between 0.1 and 6.6%, by weight.
References Cited (Backward Citations)
US2886454A
Cited
US3792553A
Cited
US3916583A
Cited
US4059417A
Cited
US4252544A
Cited
US4341533A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-16 | 1990-08-18 | 1991-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-16 | 1994-08-18 | 1995-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-16 | 1998-08-18 | 1999-02-17 | $7700.00 | Window Closed / Lapsed |