A study of phase evolution and crystal growth for nano-sized monoclinic Y4Al2O9 as a novel thermal barrier coatings

Abstract

Nano-sized monoclinic Y4Al2O9 was produced by sol-gel process as a novel potential candidate material for thermal barrier coatings. The thermal behavior, structural evolution of the products and the morphological characteristics of the compacted bodies were investigated by Thermogravimetric analysis and differential scanning calorimeter (TG-DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Field emission scanning electron microscopy (FESEM). Qualitative analyses indicate that monoclinic Y4Al2O9 was formed at about 1000 °C, and exhibited good phase stability throughout the annealing temperature ranging from 1000 °C to 1400 °C. The thermophysical properties of Y4Al2O9 ceramics were also evaluated compared with 8YSZ and La2Zr2O7. The determined activation energy of crystal growth is about 72.71 ± 0.31 kJ mol−1. Meanwhile, Y4Al2O9 represents low thermal conductivity (1.71 W m−1 K−1), moderate thermal expansion coefficient (8.73 × 10−6 K−1), and high sintering-resistance ability. Such results reveal that nano-sized Y4Al2O9 is favorable for the application of TBCs.