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 ℃. 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 °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·m1/2),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.
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