Optical, thermal properties, and hydrolysis resistance of transparent YF3-doped CaO ceramics fabricated by vacuum sintering

Transparent calcium oxide (CaO) ceramic was successfully fabricated by pressureless vacuum sintering technique with 0.5 at% YF3 as the sintering additive. In consideration of the hydrolysis of CaO, the precursor powders were calcined at 600 degrees C. Within the sintering temperature range of 1150-1450 degrees C, the effect of YF3 additive on the phase structure, relative density, transmittance, and microstructure of CaO ceramics was studied. Benefiting from the assisted liquid-phase sintering mechanism and vacancy diffusion mechanism of YF3, full-dense (3.35 g/cm(3)) YF3-doped CaO transparent ceramic was fabricated at 1350 degrees C with high thermal conductivity of 15.42 W/(m center dot K). The in-line transmittance attained 47.10% at the wavelength of 1200 nm. Moreover, the hydrolysis resistance was extremely enhanced due to the pore-free structure. Compared to the CaO ceramic with low relative density of 78.66%, the weight gain of full-dense CaO ceramic greatly decreased from 22% to 1.2% within 35 days.