Preparation and thermophysical properties of CeO2 doped La2Zr2O7 ceramic for thermal barrier coatings

Lanthanum zirconate (La2Zr2O7, LZ) and CeO2 doped La2Zr2O7 (LCZ) ceramic were synthesized by the coprecipitation-calcination method. The chemical compositions, phase compositions, thermophysical properties of these materials were investigated. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) and XRD results revealed that the compositions of all prepared ceramic materials were in the range of the synthesis of single La(2)Zr(2)O7 with pyrochlore structure. After the prepared ceramic powders were mechanically ball-milled, vacuum dried, molded by cold pressure and densified by sinter at 1650 degrees C for 10h, the bulk density of the sample was measured by the Archimedes method with an immersion medium of deionized water, a high-temperature dilatometer, DSC and laser thermal diffusivity method were used to analyze its thermal expansion coefficient, specific heat and thermal diffusivity. The results showed that, with the temperature increasing, the thermal expansion coefficient (TEC) of these ceramics increased, while the thermal conductivity decreased. The thermal expansion coefficient of La2Zr2O7 was enhanced clearly by adding CeO2, and its thermal diffusivity and specific heat were all changed slightly. The thermophysical results also indicated that TEC of LCZ was slightly higher than that of conventional Y2O3-8 wt.% ZrO2 (8YSZ), but its thermal conductivity was lower than that of 8YSZ. The lower thermal conductivity of LCZ was mainly attributed to more oxygen vacancies and larger atomic weight of substitutional atom (La, Ce). These results imply that LCZ can be explored as the candidate material for the ceramic layer in TBCs system. (C) 2006 Elsevier B.V. All rights reserved.