Preparation and properties of Yb₂O₃-Y₂O₃- Gd₂O₃-ZrO₂ ceramics for thermal barrier coatings

Yb₂O₃-Y₂O₃- Gd₂O₃-ZrO₂ (YYGZO) composition powder was synthesized by the chemical coprecipitation method using Yb₂O₃, Y₂O₃, Gd₂O₃ and ZrOCl₂· 8H₂O powders as raw materials, and applied as ceramic topcoats of thermal barrier coating (TBC) by atmospheric plasma spraying (APS). Microstructure and phases of YYGZO powder and thermal barrier coatings were examined by scanning electrical microscopy (FESEM) and X-ray diffraction (XRD). The results showed that the YYGZO ceramics powder were prepared with solid sphere shape and proper distribution of particle size about 30-60 μm by spray-dried method are suitable for atmospheric plasma spraying. Phase analyses revealed that YYGZO coatings keep the single phase before and after under heat treatment at 1200°C. The coating has compact microstructure and higher binging strength between the topcoat and bondcoat. The bingding strength and porosity of the coating are about 35.2 MPa and 9.23%, respectively.