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AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsDonald W. Wisander, Robert C. Bill
Estimating the term…
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.
In a gas path seal for a turbine or the like having a plurality of blades mounted for rotation about an axis, an improved shroud surrounding the tips of said blades in substantially concentric relationship to said axis, said shroud comprising
An abradable gas path seal between a member rotating about an axis and an annular substrate forming a shroud concentric with said axis in spaced relationship with said member comprising
Dependencies are inferred from the claim text.