Thermal Barrier Coatings on the Base of Samarium Zirconates

The zirconates of rare earth elements, such as Sm2Zr2O7, can be an alternative material for zirconia modified by yttria (8YSZ) usually used as an insulation layer in thermal barrier coatings (TBC) systems. This chapter describes the morphology of feedstock zirconate powder, internal morphology and selected properties of different samarium zirconate TBC systems. These included: composite TBC coatings of Sm2Zr2O7 + 8YSZ type with different ratio of both used to coatings deposition powders (25/75, 50/50 and 75/25) as well as the TBC of double ceramic layer (DCL) type with an 8YSZ internal layer and an outer layer of Sm2Zr2O7 type, and a monolayer TBC based on Sm2Zr2O7. Another presented subject is related to the oxidation resistance of TBC systems during static oxidation test at temperature 1100°C. In this case, the special emphasis was taken on the characterization of thermally grown oxides (TGO) zone thickness where the most important phenomena related with overall live-time of TBC systems usually take place.

Elastic Properties of Spark Plasma Sintered (SPS) ZrB2/SiC-Sm2Zr2O7 Composites

Due to extremely low oxygen transportation at elevated temperature, samarium zirconate (Sm2Zr2O7) with pyrochlore structure was introduced into ZrB2-based functional gradient composites as oxygen insulation. The elastic properties of composites with different phase ratio were investigated in this study. A series of nearly-fully dense ZrB2-based composites with different Sm2Zr2O7 content was consolidated by spark plasma sintering (SPS) technology. The microstructure and phase compositions were characterized by scanning electronic microscope (SEM) and X-ray diffraction respectively. The dynamic elastic properties were obtained by resonance method at room temperature. The results revealed that the addition of Sm2Zr2O7 can significantly improve its densification for the refractory diboride, which mainly caused by the high sintering activity of Sm2Zr2O7. Young’s modules of the series of composites obviously decreased with the increasing content of Sm2Zr2O7. The low Young’s modulus of Sm2Zr2O7 was the main reason. The Young’s modules of the series of composites were calculated theoretically. The experimental results matched the theoretical data well. A little deviation appeared due to the continuous structure of Sm2Zr2O7 in the composites.