Evaluation of the hot corrosion behavior of thermal barrier coatings

Calcium silicate and yttria-stabilized ZrO₂/(MCrAlY) thermal barrier coating systems on air-cooled specimens were exposed to sodium-plus vanadium- doped Mach 0.3 combustion gases. The thermal barrier coating endurance was determined to be a strong inverse function of the ceramic coating thickness. Coating system durability was increased through the use of NiCrAlY and CoCrAlY bond coatings with high chronium and aluminum contents. Chemical and electron microprobe analyses supported the predictions of condensate compositions and the determination of their roles in causing spalling of the ceramic coatings.