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&middot 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.