Properties of Thermal Barrier Coatings Made of Different Shapes of ZrO2-7wt%Y2O3 Powders

Atmospheric plasma sprayed ZrO2-7wt%Y2O3 (7YSZ), functioned as thermal barrier coatings (TBCs), are widely used in industrial gas turbine engines so as to protect the superalloy blades from failure. Using NiCoCrAlYTa powder as starting material a bond coating was prepared on K4169 superalloy substrate by high velocity oxygen flame (HVOF). Ceramic top coatings were prepared on the above mentioned bond coating by atmospheric plasma spray (APS) using agglomerated and sintered (referred to as “AS”) powder and hollow spherical (referred to as “HS”) powder, separately as starting materials. The microstructures of above two sorts of thermal barrier coatings (TBCs) were characterized by scanning electron microscope (SEM) and industrial computed tomography (ICT). Thermal oxidation resistance, thermal shock and adhesion strength, insulation property of both TBCs were compared. The results indicate that the TBCs made of HS have more pores and microcracks than the TBCs made of AS. Different porosities of TBCs have no obvious effect on thermal oxidation property. The TBCs made of HS have better thermal shock resistance and insulation property than the TBCs made of AS, but the formers adhesion strength is lower than the later's. The former is 35 MPa, while the later is 54 MPa.