Sintering resistance of La2Ce2O7, La2Zr2O7, and yttria stabilized zirconia ceramics

Abstract

La2Ce2O7 (LC), La2Zr2O7 (LZ), and yttria stabilized zirconia (YSZ) nanostructured powders with different agglomerate structures were successfully synthesized via wet-chemical method, and their high-temperature sintering resistance was systematically studied in this paper. Experimental results indicate that the synthesized nanostructured YSZ sample possessed the highest sintering resistance while nanostructured LC sample had the lowest sintering resistance. Theory of sintering process at initial stage was used to analyze experimental results. Sintering abilities of materials were closely related to their surface energy, lattice and grain boundary diffusion coefficients, and powder morphologies. Moreover, intrinsic sintering resistance (ISR) and extrinsic sintering resistance (ESR) were defined to further clarify the experimental results. ISR is determined by surface energy, lattice and grain boundary diffusion coefficients of the material, while ESR is affected by dimensions and density of raw powders. The highest sintering resistance of YSZ originated from dense initial powder with large size, which led to extraordinary ESR of the sample. ISR of LZ was found to be much better than that of YSZ and LC, while ISR values of LC and YSZ were similar. Finally, as ISR ability of thermal barrier coating (TBC) materials can be clarified by studying the corresponding crystalline size evolution, a feasible approach was proposed to compare ISR ability of novel TBC materials.