Segmented lanthanum cerium oxide thermal barrier coatings by atmospheric plasma spray

Recently, efforts have been focussed on seeking for new candidates as ceramic topcoat in thermal barrier coating (TBC) system, instead of yttria stabilised zirconia (YSZ) currently used for TBC topcoat. Among the candidates, lanthanum cerium oxide (La₂Ce₂O₇, LCO) is a promising TBC topcoat material, because of its higher temperature stability and better thermal insulation performance relative to yttria stabilised zirconia. In this work, the LCO TBC with high segmentation crack density was prepared by atmospheric plasma spraying, while keeping the stoichiometric composition of the coating. High plasma power and high substrate temperature T_s contribute to the formation of the segmentation structure. The segmented LCO TBC had a lifetime of >730 cycles, exhibiting a significant improvement in thermal shock resistance as compared to the nonsegmented coating. Spallation failure of the segmented TBC was caused by both chipping and delamination cracking.