| 초록 |
Non-oxygen silicon-based ceramics such as SiC/SiCf composites and silicon carbide (SiC) are of interest as candidate materials for the hot gas path parts of new-generation gas turbines because of their excellent high-temperature mechanical properties (e.g., retention of high-temperature strength and toughness up to 1600°C). However, since it is prone to hot-corrosion in thermally extreme environments, the development of environmental barrier coatings (EBCs) is mandatory [1-3]. In the present work, Y2SiO5 coatings have been deposited by flame spray technique as protection layer of SiC substrate from oxidation and steam corrosion as shown in Fig.1. Y2SiO5 coatings are isothermal heat treated by different temperatures at 1180°C and 1480°C, respectively. The thermal behaviors such as phase transformation, microstructure change of Y2SiO5 coatings and TGO deposition phenomena have been examined by XRD, SEM, and EDS analysis. The uniform TGO growth and some aggressive TGO growth behavior were found during isothermal heat treatment. The results show that the change of microstructure and composition is not too critical, but higher temperatures and longer heating times do lead to the formation of Y2SiO5 crystalline phases and a β-Y2O3 phase. In addition, the mechanical properties were evaluated by nano indentation. The isothermal heat treatment improves the hardness and elastic modulus of Y2SiO5 coatings. |
