Zirconia-based abradable coatings fabricated on single-crystal superalloy: Microstructure, residual stress and mechanical properties

Abstract

Thermal sprayed ZrO2-based abradable coatings have shown great advantages in blade/shroud clearance control systems of aero-engine turbine components due to their good high-temperature stability and abradability. Dysprosia-stabilized-zirconia (DySZ) based Abradable Coating were deposited on the Ni-based single-crystal superalloy via atmospheric plasma spraying technique. Microstructure evolution behaviors of the ZrO2-based abradable coating and the substrate were examined after 1100 ℃ thermal cycling. Besides, variation of the residual stress of the top layer was measured by Raman spectroscopy. Nanoindentation tests were conducted on the polished cross-section samples to evaluate Young's modulus and hardness evolution behavior. Results indicated that the DySZ top layer exhibits superior phase stability and good thermal shock resistance during thermal cycling. Thermally Grown Oxide (TGO) layer, Inter-Diffusion Zone (IDZ), and Second Reaction Zone (SRZ) was detected with the prolongation of the heat treatment time. Correlation between the microstructure and residual stress, hardness, Young's modulus of the coating was discussed. This study aims to further understand the relationship between the coating evolution behavior and the service time.