Microstructure and mechanical properties of Sc2O3- Y2O3 co-doped ZrO2 ceramic materials for thermal barrier coating

Partially stabilized zirconia (7YSZ ) with a mass fraction of 7 +/- 1% yttrium oxide is a widely used ceramic material for thermal barrier coatings. However , its phase stability , sintering resistance , and mechanical properties decreased during the long-time operation above 1200 degrees C. A new type of Sc2O3 -Y2O3 co -doped ZrO2 thermal barrier coating ceramic material was proposed , and a molar fraction of 7. 5%Sc2O3 - x% Y2O3 - (92. 5-x )% ZrO2 (x=0 ,0.1 ,0.2 ,0.3 ) ceramics were prepared by solid-state reaction method. The effects of Y2O3 doping on the microstructural , phase evolution , and mechanical properties (including Vickers hardness , fracture toughness , elastic modulus and three-point bending strength )were explored by XRD , SEM , and other testing methods. The results show that the relative density of Sc2O3 -Y2O3 doped ZrO2 ceramics sintered at 1450 degrees C for 3.5 h is more than 97% , and the phase structure is composed of tetragonal phase. Compared with 6-8YSZ ceramics , Sc2O3 -Y2O3 doped ZrO2 ceramics exhibit similar Vickers hardness (13-14 GPa ), fracture toughness (6.5-7.0 MPa <middle dot>m(1/2) ), elastic modulus (211-214 GPa ) and three-point bending strength (520-850 MPa ). Fracture mechanism shows a mixture of transgranular and intergranular fracture modes , in which transgranular fracture is dominant. This ceramic can be explored as a potential thermal barrier coating material for high -temperature applications.