Densification, Structure, and Thermophysical Properties of Ytterbium-Gadolinium Zirconate Ceramics

摘要

(Yb_xGd_(1-x))_2Zr_2O_7 (0≤x≤ 1.0) ceramic powders synthesized with the chemical-coprecipitation and calcination method were pressureless-sintered at 1550- 1700℃ to develop new thermal barrier oxides with a lower thermal conductivity than yttria-stabilized zirconia ceramics. (Yb_xGd_(1_x))_2Zr_2O_7 ceramics exhibit a defective fluorite-type structure. The linear thermal expansion coefficients of (Yb_xGd_(1-x))_2Zr_2O_7 ceramics increase with increasing temperature from room temperature to 1400℃. The measured thermal conductivity of (Yb_xGd_(1-x))_2Zr_2O_7 ceramics first gradually decrease with increasing temperature and then slightly increase above 800℃ because of the increased radiation contribution. YbGdZr_2O_7 ceramics have the lowest thermal conductivity among all the composition combinations studied.