Transformability of t-ZrO{sub 2} and lattice parameters in plasma sprayed rare-earth oxides stabilized zirconia coatings
- Nanyang Technological Univ., Singapore (Singapore). School of Mechanical and Production Engineering
Coatings of zirconia alloys are mostly used in high-temperature environments as thermal barrier coatings (TBC) to fight hostile working environments and boost energy efficiency. CaO, MgO and Y{sub 2}O{sub 3} are added into zirconia to stabilize the cubic and tetragonal forms and prevent catastrophic cracking as a result of the volume changes on t {r_arrow} m transformation. However, zirconia fully stabilized with either CaO or MgO has been shown to be destabilized on thermal cycling over 1,000 C. Y{sub 2}O{sub 3} stabilized ZrO{sub 2} is stable towards vaporization at high temperature (1,200 C). However, it also encounters the problem of destabilization when it is attacked by the mineral constituents in fuel oil. The destabilization resulted in a detrimental volume change of 3--5%, which can lead to failure, especially if thermal cycling across the transformation temperature takes place. Previous studies on the rare-earth oxide-zirconia system used solid state reaction of mixed powders that are likely to yield chemical inhomogeneities. Recent studies on rapid solidified ZrO{sub 2}-Y{sub 2}O{sub 3} and rare earth oxides stabilized zirconia systems by a hammer and anvil apparatus, which claims to be capable of obtaining compositional homogeneities, suggest the formation of a t{prime} phase that is non-transformable.
- OSTI ID:
- 554032
- Journal Information:
- Scripta Materialia, Vol. 37, Issue 9; Other Information: PBD: 1 Nov 1997
- Country of Publication:
- United States
- Language:
- English
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