Strain-tolerant columnar design in thick lamellar thermal barrier coatings enable long-term protection

Thickness is recognized as a key structural factor for thermal barrier coatings (TBCs), yet it often exerts opposing effects on thermal and mechanical performance, rendering it challenging to simultaneously enhance insulation and service life through conventional mono-designs. Here, thick lamellar TBCs of approximately 2 mm were tailored, and subsequently, vertical cracks were introduced by post-deposition quenching to improve cyclic strain tolerance. Controlled processing resulted in columnar structures with varying column scales w / d ( w : distance between adjacent VCs, d : depth of VCs) but comparable lamellar features. Thermal cyclic tests revealed that lifespan increased 3-fold when w / d was reduced from 2.0 to 0.7 mm. Finite element simulations further showed that although thickening of the thermally grown oxide and stiffening of the top coat increase the cracking driving force, tailoring the column scales dramatically reduces this driving force. Consequently, a strain-tolerant structure is maintained throughout thermal cycling, contributing to the prolonged lifespan of the thick TBCs.