A thermal barrier coated (TBC) turbine component design system, including an accurate TBC life prediction model, is needed to realize the full potential of available TBC engine performance and/or durability benefits. The objective of this work, which was sponsored in part by NASA under the Hot Section Technology (HOST) Program (Contract NAS3-23944), was to generate a life prediction model for electron beam-physical vapor deposited (EB-PVD) zirconia TBC. Specific results include EB-PVD zirconia mechanical and physical properties, coating adherence strength measurements, interfacial oxide growth characteristics, quantitative cyclic thermal spallation life data, and a spallation life model.

Thertn1l1 barrier coatings hnve been used for over 20 yet1rs 10 extend the durability of aircraft gus turbine engine combustors. Improvements to the chemiall composition of the ceramic and to the composition Qnd microstructure of the underlying bond coat have Ill/owed the application of thermal barrier coating technology to turbine components, with similar benefits. Recent ceramic process improvements have led to the incorporation of very durable electron beamphysical vapor deposited coatings 0" the most demJ1nding of statiol1Jlry und rotating turbine components.

Failure of a two-layer plasma-deposited thermal barrier coating is caused by cyclic thermal exposure and occurs by spallation of the outer ceramic layer. Spallation life is quantitatively predictable, based on the severity of cyclic thermal exposure. This paper describes and attempts to explain unusual constitutive behavior observed in the insulative ceramic coating layer, and presents details of the ceramic cracking damage accumulation process, which is responsible for spallation failure. Comments also are offered to rationalize the previously documented influence of interfacial oxidation on ceramic damage accumulation and spallation life.

A thermal barrier coated (TBC) turbine component design system, including an accurate TBC life prediction model, is needed to realize the full potential of available TBC engine performance and/or durability benefits. The objective of this work, which was sponsored in part by NASA under the Hot Section Technology (HOST) Program (Contract NAS3-23944), was to generate a life prediction model for electron beam - physical vapor deposited (EB-PVD) zirconia TBC. Specific results include EB-PVD zirconia mechanical and physical properties, coating adherence strength measurements, interfacial oxide growth characteristics, quantitative cyclic thermal spallation life data, and a spallation life model.