EP0395091A2
Expired / Lapsed
EP
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Sintered sol gel alumina based filament and method of making and use of same
Assignee: Saint Gobain Abrasives Inc
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Filing: 1990-04-27
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Granted: —
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Expires: 2010-04-27
Abstract
Abstract A sintered sol gel alumina based filament made up predominantly of fine alpha alumina crystals, a method of making same and use or the filament as abrasive particle and reinforcement of composite materials.
Inventors
- 👤 Charles V. Rue
- 👤 Ronald H. Van De Merwe
- 👤 Ralph Bauer
- 👤 Scott W. Pellow
- 👤 Thomas Cottringer
- 👤 Richard J. Klok
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:43
CPC Classifications
D; D01; D01F; D01F9/00; D01F9/08; C; C09; C09K; C09K3/00; C09K3/14; B; B24; B24D; B24D3/00; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; C04B35/622; C04B35/62227; C04B35/62231; C04B35/62236; C09K3/1409
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
54 words
A sintered sol gel alumina based filament comprised of sintered alpha alumina crystals having a size no greater than 2 µm preferably 1 µm, said filament having a substantially uniform cross-section, a diameter not greater than 2 mm, an average aspect ratio of at least 1.0 and a hardness of at least 16 GPa.
Claim 2
Dependent Claim
54 words
A sintered sol gel alumina based filament comprised of sintered alpha alumina crystals having a size no greater than 2 µm preferably 1 µm, said filament having a substantially uniform cross-section, a diameter not greater than 2 mm, an average aspect ratio of at least 1.0 and a hardness of at least 16 GPa.
Claim 3
Dependent Claim
15 words
A filament according to claim 1, having an aspect ratio of from 1.5 to 25.
Claim 4
Dependent Claim
29 words
A filament according to claim 1 or 2, being a particle having a length of less than 1 cm and/or a diameter of from 0.0001 mm to 2 mm.
Claim 5
Dependent Claim
28 words
A filament according to one of the preceding claims, wherein at least 80% of said filament comprises generally equiaxed crystals having a size no greater than 0.4 µm.
Claim 6
Dependent Claim
52 words
A filament according to one of the preceding claims having a density of at least 95% of theoretical density, and including from 1% to 50% by weight of an oxide selected from the group consisting of zirconia, titania, magnesia, hafnia, ceria, spinel, mullite, manganese dioxide, precursors of these oxides and mixtures thereof.
Claim 7
Dependent Claim
27 words
A filament according to one of the preceding claims wherein said alpha alumina crystals are seeded alpha alumina crystals having a size of less than 1 µm.
Claim 8
Dependent Claim
17 words
A filament of one of the preceding claims wherein said filament is curved in its longer dimension.
Claim 9
Dependent Claim
17 words
A filament of one of the preceding claims wherein said filament is twisted in its longer dimension.
Claim 10
Dependent Claim
26 words
A filament according to one of the preceding claims that is substantially free of glassy components and has a breaking strength of at least 8,000 kg/cm².
Claim 11
Independent Claim
103 words
A method of making a sintered alumina based filamentary body especially according to one of the preceding claims containing alpha alumina crystals, said alpha alumina crystals having a size of about 2 µm or less, comprising the steps of: providing a gelled dispersion of submicron hydrated alumina particles, shaping said gelled dispersion into filaments, drying the filaments, firing said dried filaments to a temperature between 1090°C and 1500°C for a time selected to convert the alumina in said filaments to a ceramic body, the major portion of which is made up of alpha alumina crystals of about 2 µm or less in size.
Claim 12
Dependent Claim
46 words
The method of claim 10, wherein said gelled dispersion includes an effective amount of sub-micron seed particles for facilitating the rapid conversion of said hydrated alumina particles to alpha alumina upon sintering, said alpha alumina crystals having a crystal size of about 1 um or less.
Claim 13
Dependent Claim
22 words
The method of claim 10 or 11 wherein said alpha alumina crystals have a crystal size of about 0.4 µm or less.
Claim 14
Independent Claim
62 words
The method of one of claims 10 to 12 wherein said seed particles are selected from the group consisting of alpha alumina, alpha ferric oxide, gamma alumina, chromium oxide; precursors of alpha alumina, gamma alumina, chromium oxide, and alpha ferric oxide; and mixtures thereof, and the seed particles are present in an amount of from about 0.5% to about 10% by weight.
Claim 15
Independent Claim
23 words
The method of one of claims 10 to 13 wherein said shaping of the gelled dispersion is done by extrusion or by spinning.
Claim 16
Dependent Claim
18 words
A sintered sol gel alumina based filament obtainable by the method of one of claims 10 to 14.
Claim 17
Dependent Claim
17 words
Use of a filament of one of the claims 2 to 9 or 15, as abrasive particle.
Claim 18
Dependent Claim
25 words
Use of the filament according to claim 16 in bonded abrasive products, especially grinding wheels or segments or in coated products especially belts or discs.
Claim 19
Dependent Claim
22 words
Use of a filament according to one of claims 1 to 9 or 15 for reinforcement in a metal and/or ceramic composite.
Claim 20
Dependent Claim
19 words
A metal or ceramic composite reinforced with a filament according to one of claims 1 to 9 or 15.
References Cited (Backward Citations)
No citation records indexed.
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