Yttria stabilized zirconia(YSZ) | Optical characterization of thin films

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Yttria stabilized zirconia know as YSZ is one of the most well known materials used as in thermal barrier coatings (TBC). 8-YSZ has gained widespread acceptance as a TBC material for turbine applications and is generally applied by either the plasma spray or electron-beam physical vapor deposition (EB-PVD). TBCs applied by EB-PVD have advantages over those applied by the plasma spray process, including better strain tolerance, erosion-resistance, bond strength, and surface roughness.

TBCs on advanced turbine blades considerably increase the engine efficiency and blade performance in gas turbines. TBCs usually consist of a substrate, metallic bond (bond coat), thermally grown oxide (TGO), and ceramic top coat. The TGO layer forms as a result of bond coat oxidation, which usually plays the most important role in determining the lifetime of the TBC. The ceramic top coat consists of Y2O3 partially stabilized ZrO2 or Y2O3-stablilized HfO2 deposited by EB-PVD or plasma spraying. The EB-PVD process creates a columnar microstructure, exhibiting superior strain and thermal shock tolerance. YSZ is a standard material for current TBC applications because of its low thermal conductivity, relatively high coefficient of thermal expansion, and chemical inertness in many combustion atmospheres.