Phase and structural evolution of dysprosia stabilized zirconia ceramics under CMAS corrosion environment

In this study, 10 wt % dysprosia stabilized zirconia (10DySZ) ceramics were prepared by pressureless sintering method. The CMAS corrosion behaviors of DySZ ceramics were investigated and the corrosion mechanism was also discussed in detail. Results show that the CMAS corrosive agent can induce phase transformation of DySZ ceramic due to the stronger ability to capture Dy stabilizers than Zr ions. During the corrosion process, molten CMAS would preferentially corrode the grain boundaries and then infiltrated into the interior of DySZ ceramic, resulting in the formation of loose structure on the ceramic surface. Sandy-shaped DySZ particles were also formed in the residual CMAS layers based on dissolution and precipitation mechanism. The corrosion temperature plays a crucial role in accelerating the phase transformation and thermal-mechanical damage of DySZ ceramic. Mismatch of thermal expansion coefficient between CMAS and DySZ ceramics as well as composition and structural difference between dense layer and porous layer are all responsible to the formation of destructive cracks.