Abstract
Lanthanum magnesium hexaluminate (LaMgAl11O19, LMA) is an attractive material for thermal barrier coatings (TBCs), and the failure of its coating was studied in this work by thermal cycling, X-ray diffraction, dilatometric measurement and thermal gravimetric-differential thermal analysis. The dilatometric measurement indicates that even though the bulk material of LMA has a higher sintering-resistance than the typical TBC material, i.e. yttria-stabilized zirconia (YSZ), the plasma sprayed coating of LMA has two serious contractions due to the re-crystallization of LMA and phase transitions of alumina. LMA has similar thermal expansion behaviour with alumina, leading to a good thermal expansion match between LMA and the thermally grown oxide layer. On the other hand, the plate-like structure of LMA not only results in a low thermal conductivity, low Young's modulus, but also a high stress tolerance, and these are believed to be the reasons for the long thermal cycling life of LMA coating.
Original language | English |
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Pages (from-to) | 1979-1986 |
Number of pages | 8 |
Journal | Journal of the European Ceramic Society |
Volume | 28 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2008 |
Externally published | Yes |
Keywords
- Lanthanum magnesium hexaluminate
- Phase stability
- Plasma spraying
- Thermal barrier coatings