Application Study on Ceria Based Thermal Barrier Coatings

✍ Scribed by J. Wilden; A. Wank

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 313 KB
• Volume: 32
• Category: Article
• ISSN: 0933-5137
• DOI: 10.1002/1521-4052(200108)32:8<654::aid-mawe654>3.0.co;2-4

✦ Synopsis

The industrial application of APS sprayed YPSZ coatings for thermal insulation is established in several branches. As the main potential to increase the efficiency of combustion processes is thermal efficiency and the state-of-the-art systems are limited to surface temperatures below 1200 8C for long term applications, there is interest in concepts, that allow an increase of the process temperature. Ceria and ceria based ceramics show an outstanding potential for use at temperatures exceeding 1200 8C. A triple-layer thermal barrier system in consideration of the established system ± MCrAlY bond coat and YPSZ ± and an additional ceria based top coating are investigated. TBC systems with two different ceria powders are produced by APS and HVOF spraying and evaluated with concern to the microstructure, bond strength, thermal shock behaviour and long term compatibility of the constituents. HVOF sprayed coatings contain more oxygen, are more dense than APS sprayed coatings and do not show segmentation due to cracks perpendicular to the surface. APS sprayed pure ceria coatings show a columnar morphology inside single splats forming the coating. The bond between YPSZ and ceria and the total bond strength of the thermal barrier system exceeds the cohesion inside the ceria coating. The thermal shock resistance of ceria coatings with high silica and sulphur content is low. Long term sintering investigations prove the compatibility of ceria and YPSZ at 1150 8C.