Revisiting the Birth of 7YSZ Thermal Barrier Coatings: Stephan Stecura

Thermal barrier coatings are widely used in all turbine engines, typically using a 7 wt.% Y2O3–ZrO2 formulation. Extensive research and development over many decades have refined the processing and structure of these coatings for increased durability and reliability. New compositions demonstrate som...

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Bibliographic Details
Published inCoatings (Basel) Vol. 8; no. 7; p. 255
Main Authors Smialek, James, Miller, Robert
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 22.07.2018
Subjects
Aircraft
Coatings
Composition
Plasma
Precipitates
Process controls
R&D
Research & development
Thermal barrier coatings
Thermal cycling
Turbine engines
Yttria-stabilized zirconia
Yttrium oxide
Zirconium dioxide
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Summary:Thermal barrier coatings are widely used in all turbine engines, typically using a 7 wt.% Y2O3–ZrO2 formulation. Extensive research and development over many decades have refined the processing and structure of these coatings for increased durability and reliability. New compositions demonstrate some unique advantages and are gaining in application. However, the “7YSZ” (7 wt.% yttria stabilized zirconia) formulation predominates and is still in widespread use. This special composition has been universally found to produce nanoscale precipitates of metastable t’ tetragonal phase, giving rise to a unique toughening mechanism via ferro-elastic switching under stress. This note recalls the original study that identified superior properties of 6–8 wt.% yttria stabilized zirconia (YSZ) plasma sprayed thermal barrier coatings, published in 1978. The impact of this discovery, arguably, continues in some form to this day. At one point, 7YSZ thermal barrier coatings were used in every new aircraft and ground power turbine engine produced worldwide. 7YSZ is a tribute to its inventor, Dr. Stephan Stecura, NASA retiree.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings8070255