Ultrathick thermal barrier coatings enabled by additive manufactured alloys with novel surface features

Thermal barrier coatings are widely used in gas turbines to protect structural alloys from thermal damage. Typically, durability issues limit the thicknesses of these coatings to between 0.2 and 1 millimeter as a result of stresses generated by the thermal expansion mismatch between the coating and substrate. Historically several pathways for enhanced strain tolerance have been pursued ranging from increased porosity to the production of intentionally segmented coatings. In this study, Haynes 282 samples with cellular honeycomb surface features were produced through a laser powder bed fusion process and coated with ultrathick (up to 10 mm) yttria-stabilized zirconia overlays. The substrate features provide enhanced resistance to delamination cracking and promote the formation of compliant feather-like microstructures adjacent to the cell walls. Both featured and conventional coated substrates were tested in a high heat flux thermal gradient test rig, with featured substrates exhibiting a cycling life ranging from 25 to 100x the tested unfeatured samples.