Thermal barrier coatings for aeroengine applications

Thermal barrier coatings (TBCs) have been in use in aeroturbine engine hot sections for over 20 years. The initial applications were driven by the need to suppress component degradation caused by excessive thermal gradients in vane airfoils. A TBC is essentially a layered, multimaterial structure that must withstand harsh temperature, environmental, thermal cycling, and stress conditions for an extended number of aircraft takeoffs and landings. A description of the TBC materials systems presently in use is presented, together with a summary of current understanding of materials and failure issues in TBCs.