US4960441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sintered alumina-zirconia ceramic bodies
Assignee: Saint Gobain Abrasives Inc
•
Filing: 1988-05-09
•
Granted: 1990-10-02
•
Expires: 2008-05-09
Abstract
Abstract Useful ceramic bodies can be made by mixing zirconia powder with seeded alumina gel, drying, and firing at a high enough temperature to convert the alumina in the gel to microcrystalline alpha alumina. Abrasive grits made in this way, with a zirconia content between 15 and 30 weight percent and at least half the zirconia in the tetragonal crystal form are particularly valuable for use in grinding wheels for snagging steels.
Inventors
- 👤 Scott W. Pellow
- 👤 Ronald W. Trischuk
- 👤 Christopher E. Knapp
- 👤 Ralph Bauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:32
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/117; C04B35/119; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C09K3/1427
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
67 words
A ceramic body comprising well intermixed microcrystals of alpha alumina and zirconia with at least three-fourths of said microcrystals appearing to have a maximum dimension between 0.25 and 1 micron when viewed in cross section in an electron micrograph at a magnification of about 10,000-20,000 X, said ceramic body containing from 50 to 95 weight percent of alumina and from 50 to 5 weight percent of zirconia.
Claim 2
Dependent Claim
67 words
A ceramic body comprising well intermixed microcrystals of alpha alumina and zirconia with at least three-fourths of said microcrystals appearing to have a maximum dimension between 0.25 and 1 micron when viewed in cross section in an electron micrograph at a magnification of about 10,000-20,000 X, said ceramic body containing from 50 to 95 weight percent of alumina and from 50 to 5 weight percent of zirconia.
Claim 3
Dependent Claim
18 words
A ceramic body according to claim 1, having a three point bend strength of at least 0.9 gigapascals.
Claim 4
Dependent Claim
15 words
A ceramic body according to claim 2, having a hardness of at least 17 gigapascals.
Claim 5
Dependent Claim
19 words
A ceramic body according to claim 3, having a fracture toughness of at least 4 megapascal (meter) 0 .5.
Claim 6
Dependent Claim
19 words
A ceramic body according to claim 1, wherein said microcrystals have an average size of less than 0.5 microns.
Claim 7
Dependent Claim
12 words
An abrasive grit that is a ceramic body according to claim 1.
Claim 8
Dependent Claim
21 words
An abrasive grit according to claim 6, containing from 70-85 weight percent of alumina and from 30-15 weight percent of zirconia.
Claim 9
Dependent Claim
19 words
An abrasive grit according to claim 7, wherein said microcrystals have an average size of less than 0.5 microns.
Claim 10
Dependent Claim
21 words
An abrasive grit according to claim 8, wherein at least one half the zirconia is present in the tetragonal crystal form.
Claim 11
Dependent Claim
24 words
An abrasive grit according to claim 9, wherein at least one fifth of the zirconia contained in the grit has the monoclinic crystal form.
Claim 12
Dependent Claim
76 words
A sintered abrasive grit containing from 70-85 weight percent of alumina and 30-15 weight percent of zirconia, both the alumina and the zirconia being in the form of crystals, wherein the alumina crystals have an apparent average size of about 1 micron or less when viewed in cross section in an electron microscope at a magnification of about 10,000-20,000 X, at least one half of the zirconia contained in the grit having the tetragonal crystal form.
Claim 13
Dependent Claim
76 words
A sintered abrasive grit containing from 70-85 weight percent of alumina and 30-15 weight percent of zirconia, both the alumina and the zirconia being in the form of crystals, wherein the alumina crystals have an apparent average size of about 1 micron or less when viewed in cross section in an electron microscope at a magnification of about 10,000-20,000 X, at least one half of the zirconia contained in the grit having the tetragonal crystal form.
Claim 14
Dependent Claim
21 words
A sintered abrasive grit according to claim 11, wherein said crystals have an apparent average size of less than 0.5 microns.
Claim 15
Dependent Claim
22 words
A sintered abrasive grit according to claim 12, wherein at least one-fifth of the zirconia present is in the monoclinic crystal form.
Claim 16
Dependent Claim
22 words
A sintered abrasive grit according to claim 13, wherein at least one-fifth of the zirconia present is in the monoclinic crystal form.
Claim 17
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 14 are bonded by a thermoset phenolic resin.
Claim 18
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 13 are bonded by a thermoset phenolic resin.
Claim 19
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 12 are bonded by a thermoset phenolic resin.
Claim 20
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 11 are bonded by a thermoset phenolic resin.
Claim 21
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 10 are bonded by a thermoset phenolic resin.
Claim 22
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 9 are bonded by a thermoset phenolic resin.
Claim 23
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 8 are bonded by a thermoset phenolic resin.
Claim 24
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 7 are bonded by a thermoset phenolic resin.
Claim 25
Dependent Claim
18 words
A grinding wheel in which abrasive grits according to claim 6 are bonded by a thermoset phenolic resin.
Claim 26
Dependent Claim
120 words
A process for making ceramic bodies, comprising the steps of: (a) mixing together to form a seeded sol (i) powdered zirconia, (ii) monohydrated alumina, (iii) water, and (iv) a sufficient amount of fine crystalline seeds to facilitate the transformation of monohydrated alumina to crystalline alpha alumina upon heating; (b) treating the sol formed in part (a) to produce a gel; (c) shaping the gel formed in part (b) into coherent green bodies; and (d) heating the green bodies sufficiently to convert the monohydrated alumina content of the bodies to alpha alumina crystals, said crystals having a maximum dimension of about 1 micron or less when viewed in cross section in an electron micrograph at a magnification of about 10,000-20,000 X.
Claim 27
Dependent Claim
120 words
A process for making ceramic bodies, comprising the steps of: (a) mixing together to form a seeded sol (i) powdered zirconia, (ii) monohydrated alumina, (iii) water, and (iv) a sufficient amount of fine crystalline seeds to facilitate the transformation of monohydrated alumina to crystalline alpha alumina upon heating; (b) treating the sol formed in part (a) to produce a gel; (c) shaping the gel formed in part (b) into coherent green bodies; and (d) heating the green bodies sufficiently to convert the monohydrated alumina content of the bodies to alpha alumina crystals, said crystals having a maximum dimension of about 1 micron or less when viewed in cross section in an electron micrograph at a magnification of about 10,000-20,000 X.
Claim 28
Dependent Claim
31 words
A process according to claim 24, wherein said amount of fine crystalline seeds is no more than 10 weight percent of the alumina content of the monohydrated alumina in the sol.
Claim 29
Dependent Claim
31 words
A process according to claim 25, wherein said amount of fine crystalline seeds is at least 0.6 weight percent of the alumina content of the monohydrated alumina in the seeded sol.
Claim 30
Dependent Claim
24 words
A process according to claim 26, wherein said fine crystalline seeds have a specific surface area of at least 60 square meters per gram.
Claim 31
Dependent Claim
12 words
A process according to claim 27, wherein said seeds are alpha alumina.
Claim 32
Dependent Claim
12 words
A process according to claim 26, wherein said seeds are alpha alumina.
Claim 33
Dependent Claim
12 words
A process according to claim 25, wherein said seeds are alpha alumina.
Claim 34
Dependent Claim
12 words
A process according to claim 24, wherein said seeds are alpha alumina.
Claim 35
Dependent Claim
12 words
A process according to claim 31, wherein said monohydrated alumina is boehmite.
Claim 36
Dependent Claim
12 words
A process according to claim 30, wherein said monohydrated alumina is boehmite.
Claim 37
Dependent Claim
12 words
A process according to claim 29, wherein said monohydrated alumina is boehmite.
Claim 38
Dependent Claim
12 words
A process according to claim 28, wherein said monohydrated alumina is boehmite.
Claim 39
Dependent Claim
21 words
A process according to claim 32, wherein at least one half of said powdered zirconia is in the tetragonal crystal form.
Claim 40
Dependent Claim
21 words
A process according to claim 36, wherein at least one fifth of said powdered zirconia is in the monoclinic crystal form.
References Cited (Backward Citations)
US3079243A
Cited
US3181939A
Cited
US3481723A
Cited
US3454385A
Cited
US3387957A
Cited
US3607162A
Cited
US3679383A
Cited
US3891408A
Cited
US3831857A
Cited
US4298385A
Cited
US4690692A
Cited
US4218253A
Cited
US4314827A
Cited
US4316964A
Cited
US4565792A
Cited
US4457767A
Cited
EP0152768B1
Cited
US4623364A
Cited
US4666467A
Cited
EP0257969A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-10-01 | 1994-04-02 | 1994-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-01 | 1998-04-02 | 1998-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-01 | 2002-04-02 | 2002-10-02 | $7700.00 | Window Closed / Lapsed |