High-Temperature Chemical Stability of Hf_6Ta_2O_(17) Ceramic for Thermal Barrier Coatings

摘要

High-temperature chemical stabilities of Hf_6Ta_2O_(17)/Al_2O_3, Hf_6Ta_2O_(17)/YSZ and Hf_6Ta_2O_(17)/Sm_2Zr_2O_7 were studied for thermal barrier coatings (TBCs). The mixed powders of Hf_6Ta_2O_(17)/Al_2O_3 and Hf_6Ta_2O_(17)/YSZ were annealed at 1600°C for 8 hours in air, and the mixed powders of Hf_6Ta_2O_(17)/Sm_2Zr_2O_7 were annealed at 1200°C for 8 hours in air. The phases of the mixed powders after annealed were observed by X-ray diffractometry (XRD). The sample of Hf_6Ta_2O_(17)/Al_2O_3 mixed powder was molded and sintered at 1600°C for 8 hours in air, and the microstructures of the sintered sample were investigated by scanning electron microscopy (SEM). The XRD results revealed that the crystal structure of Hf_6Ta_2O_(17) had no remarkable changes in the mixed powders of Hf_6Ta_2O_(17)/YSZ and it had changes in the mixed powders of Hf_6Ta_2O_(17)/Al_2O_3. The monocline Hf_6Ta_2O_(17) phases were found in the mixed powders of Hf_6Ta_2O_(17)/Sm_2Zr_2O_7. The SEM results showed that the boundaries of Hf_6Ta_2O_(17) and Al_2O_3 crystals were clear. The element composes in crystals were analyzed by energy dispersive spectrometer (EDS), and the EDS results showed that a little amount of Al diffused into Hf_6Ta_2O_(17) crystals.