Thermo-optical properties of LaMg_1-xNi_xAl_11O_19 (0≤x≤1) hexaaluminates for metallic thermal protection system

摘要

LaMg_1-xNUAl_11O_19 (x = 0, 0.25, 0.5, 0.75, 1) ceramics are fabricated by pressureless-sintering method at 1700 ℃ for 10 h in air. The microstructure and thermo-optical properties of LaMg_1-xNi_xAl_11O_19 ceramics are investigated by the X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. The influence of NiO doping on structure and thermo-optical properties of LaMg_1-xNi_xAl_11O_19 ceramics is investigated. The partial substitution of Ni~2+ for Mg~2 + results in a significant increase in emissivity at low wavelengths as compared with unmodified LaMgAl_11O_19. When the Ni~2+ content increases to x = 0.75 or above, LaMg_1-xNi_xAl_11O_19 ceramics have a high emissivity value above 0.70 at low wavelengths at 500 ℃. The measured emissivity of all LaMg_1-xNi_xAl_11O_19 ceramics shows a similar trend in the wavelength range of 6 to 14 μm.