Identification of <i>t'</i> Phase in ZrO ₂ ‐7.5 wt% Y ₂ O ₃ Thermal‐Barrier Coatings

Abstract

The presence of nontransformable tetragonal (t') phase in plasma‐sprayed ZrO 2 ‐Y 2 O 3 coatings enhances the stability of the coating during high‐temperature exposure. In this paper, we describe the importance and procedure for correctly identifying t’phase in X‐ray diffraction patterns of the as‐sprayed and heat‐treated coatings. The results agree with the phase diagram. We also point out that in the heat‐treated materials, the durability should be specified in terms of t'‐ZrO 2 .