Patent US4767727A successfully refreshed from Google Patents.
US4767727A
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Fibre-strengthened ceramic formed bodies
Assignee: Max-Planck-Gesellschaft zur Förderung der Wissenschaften eV
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Filing: 1986-05-23
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Granted: 1988-08-30
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Expires: 2006-05-23
Abstract
Abstract The present invention provides a fibre-strengthened ceramic formed body with improved mechanical strength, wherein it contains at least 15% by volume of zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition in the form of monoclinic crystals and an amount of inorganic fibres sufficient for increasing the strength, which is obtainable by hot pressing a mixture of ceramic matrix materials, at least 15% by volume of tetragonal zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition particles and the fibres at a temperature above the tetragonal→monoclinic transition temperature. The present invention also provides a process for the production of such a ceramic formed body.
Inventors
- 👤 Nils Claussen
- 👤 Gunter Petzow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:09
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/117; C04B35/119; C04B35/16; C04B35/18; C04B35/185; C04B35/195; C04B35/48; C04B35/486; C04B35/488; C04B35/4885; C04B35/622; C04B35/64; C04B35/645; C04B35/71; C04B35/78; C04B35/80
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
89 words
A fibre-strengthened ceramic formed body with improved mechanical strength comprising at least 15% by volume of zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition in the form of monoclinic crystals and an amount of inorganic fibres sufficient for increasing the strength, in a ceramic matrix material, said formed body being formed by hot pressing the mixture of ceramic matrix material, at least 15% by volume of tetragonal zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition particles and the fibres, at a temperature above the tetragonal→monoclinic transition temperature.
Claim 2
Dependent Claim
89 words
A fibre-strengthened ceramic formed body with improved mechanical strength comprising at least 15% by volume of zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition in the form of monoclinic crystals and an amount of inorganic fibres sufficient for increasing the strength, in a ceramic matrix material, said formed body being formed by hot pressing the mixture of ceramic matrix material, at least 15% by volume of tetragonal zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition particles and the fibres, at a temperature above the tetragonal→monoclinic transition temperature.
Claim 3
Dependent Claim
17 words
The formed body of claim 1, wherein the proportion of fibres is at least 2% by volume.
Claim 4
Dependent Claim
18 words
The formed body of claim 1, wherein the proportion of fibres is from 4 to 50% by volume.
Claim 5
Dependent Claim
15 words
The formed body of claim 1, wherein the fibres consist wholly or partly of whiskers.
Claim 6
Dependent Claim
25 words
The formed body of claim 4, wherein the whiskers consist of SiC, Si 3 N 4 , Al 2 O 3 or any combination thereof.
Claim 7
Dependent Claim
17 words
The formed body of claim 5, wherein the whiskers have a thickness of 0.1 to 5 μm.
Claim 8
Dependent Claim
46 words
The formed body of claim 1, wherein the ceramic matrix material consists of Al 2 O 3 , partially stabilized zirconia, tetragonal zirconia polycrystals, cordierite, mullite, Mg--Al spinel, Al 2 TiO 5 , zircon, Si 3 N 4 , B 4 C or a mixture thereof.
Claim 9
Dependent Claim
22 words
The formed body of claim 1, wherein the monoclinic crystals are present in an amount of from 18 to 60% by volume.
Claim 10
Dependent Claim
40 words
The formed body of claim 4, comprising the ceramic matrix material of partly stabilised or finely crystalline tetragonal zirconium dioxide, at least 20% by weight of the whiskers and having a break resistance K Ic of at least 10 MPa√m.
Claim 11
Dependent Claim
17 words
The formed body of claim 4 wherein the whiskers have a thickness of 0.1 to 5 μm.
Claim 12
Dependent Claim
36 words
The formed body of claim 7 wherein the proportion of fibers is at least 2% by volume, the fibers comprising whiskers of SiC, Si 3 N 4 , Al 2 O 3 or any combination thereof.
Claim 13
Dependent Claim
36 words
The formed body of claim 4 comprising the ceramic matrix material of partly stabilised or finely crystalline tetragonal zirconium dioxide, 18-60% by volume of the monoclinic crystals and 4 to 50% by volume of the whiskers.
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) | 1991-08-30 | 1992-02-29 | 1992-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-30 | 1996-02-29 | 1996-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-30 | 2000-02-29 | 2000-08-30 | $7700.00 | Window Closed / Lapsed |