Yttria-stabilized zirconia, usually zirconium oxide with 7 to 8 percent yttria by weight (7YSZ or 8YSZ). The yttria keeps the zirconia in a tough, metastable tetragonal form, and the sprayed coating combines very low thermal conductivity, around 1 W/m K, with thermal expansion closer to metals than most ceramics. Above roughly 1,200 °C in long service it sinters and changes phase, which limits its life.
Top coat is 8 percent YSZ, 0.015 thick, porosity 12 to 18 percent on the image analysis.
Also heard as
- yttria-stabilized zirconia
- 8YSZ
- 7YSZ
- zirconia
Related terms
Thermal barrier coating
A ceramic coating system that insulates hot-section metal parts from combustion gas temperatures.
Top coat
The outer, functional layer of a multilayer coating, sprayed over the bond coat.
DVC
Dense vertically cracked: a thermal barrier sprayed hot so it forms deliberate through-thickness cracks.
Porosity
The fraction of a coating's volume made of voids between and within splats, usually reported in percent.