US4430360A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating an abradable gas path seal
Assignee: UNITED STATES REPRESENTED BY ADMINISTRATOR OF NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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Filing: 1982-09-30
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Granted: 1984-02-07
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Expires: 2002-09-30
Abstract
Abstract This invention is directed to improving the thermal shock resistance of a ceramic layer. The invention is particularly directed to an improved abradable lining (16) that is deposited on a shroud (14) forming a gas-path seal in turbomachinery. Improved thermal shock resistance of a shroud is effected through the deliberate introduction of "benign" cracks. These are microcracks which will not propagate appreciably upon exposure to the thermal shock environment in which a turbine seal must function. Laser surface fusion treatment is used to introduce these microcracks. The ceramic surface is laser scanned to form a continuous dense layer as shown in FIG. 2. As this layer cools and solidifies, shrinkage results in the formation of a very fine crack network. The presence of this deliberately introduced fine crack network precludes the formation of a catastrophic crack during thermal shock exposure.
Inventors
- 👤 Robert C. Bill
- 👤 Donald W. Wisander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:32
CPC Classifications
C; C23; C23C; C23C4/00; C23C4/18; F; F01; F01D; F01D11/00; F01D11/08; F01D11/12; F01D11/122; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24471
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
87 words
A method of fabricating an abradable gas path seal between the tips of a plurality of blades rotating about an axis and an annular substrate forming a shroud concentric with said axis in spaced relationship with said blade tips comprising the steps of plasma spraying a coating of a ceramic material onto the surface of said annular substrate facing said rotating blades, and forming a fine microcrack network in the surface of said ceramic coating for precluding the formation of a catastrophic crack during thermal shock exposure.
Claim 2
Independent Claim
87 words
A method of fabricating an abradable gas path seal between the tips of a plurality of blades rotating about an axis and an annular substrate forming a shroud concentric with said axis in spaced relationship with said blade tips comprising the steps of plasma spraying a coating of a ceramic material onto the surface of said annular substrate facing said rotating blades, and forming a fine microcrack network in the surface of said ceramic coating for precluding the formation of a catastrophic crack during thermal shock exposure.
Claim 3
Dependent Claim
34 words
A method of fabricating an abradable gas path seal as claimed in claim 1 wherein the microcrack network is generated by scanning a low power laser beam over the surface of the ceramic coating.
Claim 4
Dependent Claim
54 words
A method of fabricating an abradable gas path seal as claimed in claim 2 wherein the surface of the ceramic coating is laser scanned sufficiently to melt a thin layer of ceramic material at said surface whereby a very fine crack network forms from the shrinkage resulting from cooling and solidification of said layer.
Claim 5
Dependent Claim
34 words
A method of fabricating an abradable gas path seal as claimed in claim 3 wherein the fused layer is producing by scanning a low power laser beam from a continuous wave CO 2 .
Claim 6
Dependent Claim
28 words
A method of fabricating an abradable gas path seal as claimed in claim 4 wherein the laser beam has a diameter between about 0.030 inch and 0.040 inch.
Claim 7
Dependent Claim
43 words
A method of fabricating an abradable gas path seal as claimed in claim 5 wherein the ceramic coating is scanned with the laser beam at a rate of about one inch per second, said laser beam having a power of about 175 W.
Claim 8
Dependent Claim
40 words
A method of fabricating an abradable gas path seal as claimed in claim 1 wherein the microcrack network is generated by uniformly heating the seal to an elevated temperature, and quenching the hot ceramic surface to form the crack network.
Claim 9
Dependent Claim
30 words
A method of fabricating an abradable gas path seal as claimed in claim 7 wherein the seal is heated to a temperature between 950° and 1,000° F. prior to quenching.
Claim 10
Dependent Claim
21 words
A method of fabricating an abradable gas path seal as claimed in claim 8 wherein the suface is quenched in ethanol.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-06 | 1987-08-08 | 1988-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-06 | 1991-08-08 | 1992-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-06 | 1995-08-08 | 1996-02-07 | $7700.00 | Window Closed / Lapsed |