Calcia-doped yttria-stabilized zirconia for thermal barrier coatings: synthesis and characterization
- 267 Downloads
Doping with other oxides has been a stabilization method of ZrO2 for thermal barrier coating applications. Such a stabilized system is 7–8 mol% YO1.5-doped zirconia (7YSZ), which has been in use for around 20 years. In this study, calcia (CaO) and yttria (Y2O3) have been used for doping ZrO2 to produce a stable single-phase cubic calcia-doped yttria-stabilized zirconia (CaYSZ). This has been synthesized using wet chemical synthesis as well as by solid-state synthesis. Unlike partially stabilized zirconia where 5 mol% CaO is doped into ZrO2, CaYSZ has been found to be stable up to 1600 °C. Detailed CaYSZ synthesis steps and phase characterization are presented. Wet chemical synthesis resulted in a stable single-phase CaYSZ just after 4 h treatment at 1400 °C, whereas a 36 h annealing at 1600 °C is required for CaYSZ synthesis during solid-state processing. The CaYSZ has been found stable even for 600 h at 1250 °C. Coefficient of thermal expansion and sintering temperature of CaYSZ was found to be 11 × 10−6 K−1 and 1220 °C, respectively, which are comparable to 7YSZ. An increase in sintering rate with increasing dopant concentration has also been observed.
KeywordsY2O3 Thermal Barrier Coating Monoclinic Phase Thermal Barrier Coating Partially Stabilize Zirconia
Authors would like to thank Dr. O. Fabrichnaya for important suggestions. Authors would also like to thank Dr. G. Witz for useful suggestions and discussions. Authors are indebted to Innovation Promotion Agency (CTI) of Swiss Federal Office for Professional Education and Technology (Project 8974.1 PFIW-IW) for financial support.