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NASA / TMn 1999-209069 Thermal Conductivity and Elastic Modulus Evolution of Thermal Barrier Coatings Under High Heat Flux Conditions
| Content Provider | Semantic Scholar |
|---|---|
| Author | Robert Miller |
| Abstract | Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may be encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8%Y203 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m-K to 1.15 W/m-K, 1.19 W/m-K and 1.5 W/m-K after 30 hour testing at surface temperatures of 990 °C, 1100, and 1320 °C, respectively. Hardness and modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using thelaser sintering/creep and micro-indentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface, and to 7.5 GPa at the ceramic coating surface after 120 hour testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced micro-porosity gradients under the laserimposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various thermal barrier coating applications. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990047263.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Barrier function Biological Evolution Coating Excipient Differential Thermal Analysis Elastic Fibers Flux Gradient Hardness Tests Instruction creep Interface Device Component Kinetics Internet Protocol Modulus of continuity Modulus robot TBC Thermal Conductivity Thermal barrier coating United States National Aeronautics and Space Administration |
| Content Type | Text |
| Resource Type | Article |
