Development of a plasma-sprayed ceramic gas path seal for high pressure turbine applications. Final report, 2 Oct 1975--Dec 1976. [Layered yttria-stabilized zirconia (ZrO/sub 2//metal(CoCrAlY) seal]
The plasma-sprayed, graded, layered yttria-stabilized zirconia (ZrO/sub 2/)/metal(CoCrAlY) seal system for gas turbine blade tip applications up to 1589 K (2400 F) seal temperatures was studied. Abradability, erosion, and thermal fatigue characteristics of the graded layered system were evaluated by rig tests. Satisfactory abradability and erosion resistance was demonstrated. Encouraging thermal fatigue tolerance was shown. Initial properties for the plasma-sprayed materials in the graded, layered seal system was obtained, and thermal stress analyses were performed. Sprayed residual stresses were determined. Thermal stability of the sprayed layer materials was evaluated at estimated maximum operating temperatures in each layer. Anisotropic behavior in the layer thickness direction was demonstrated by all layers. Residual stresses and thermal stability effects were not included in the analyses. Analytical results correlated reasonably well with results of the thermal fatigue tests. Analytical application of the seal system to a typical gas turbine engine application predicted performance similar to rig specimen thermal fatigue performance. A model for predicting crack propagation in the sprayed ZrO/sub 2//CoCrAlY seal system was proposed, and recommendations for improving thermal fatigue resistance were made. Seal system layer thicknesses were analytically optimized to minimize thermal stresses in the abradability specimen during thermal fatigue testing. Rig tests on the optimized seal configuration demonstrated some improvement in thermal fatigue characteristics.
- Research Organization:
- Pratt and Whitney Aircraft, East Hartford, Conn. (USA). Commercial Products Div.
- OSTI ID:
- 5378115
- Report Number(s):
- N-77-25534; NASA-CR-135183; PWA-5521
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103 -- Metals & Alloys-- Mechanical Properties
360105 -- Metals & Alloys-- Corrosion & Erosion
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360205 -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ABRASION
ALLOYS
ALUMINIUM ALLOYS
CHALCOGENIDES
CHROMIUM ALLOYS
COBALT ALLOYS
CRACKS
EROSION
FATIGUE
GAS TURBINES
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
SEALS
THERMAL FATIGUE
TRANSITION ELEMENT COMPOUNDS
TURBINE BLADES
TURBINES
TURBOMACHINERY
VERY HIGH TEMPERATURE
YTTRIUM ALLOYS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES