Effect of doping REO (RE=La, Ce, Nd, Gd) on microstructures, mechanical properties and cavitation erosion performance of YSZ ceramics

Yttria-stabilized zirconia (YSZ) ceramic-based flow passage components are highly susceptible to cavitation erosion. To counter this limitation, rare-earth oxide (REO, RE=La, Ce, Nd, Gd) doped YSZ with superior cavitation erosion resistance was successfully prepared using spark plasma sintering technology. The microstructures, phase compositions, mechanical properties, and cavitation erosion resistance of YSZ and REYSZ were investigated. The results indicate that REO doping promoted the generation of t'- and c-phases, leading to a denser structure and grain refinement. Moreover, the presence of a larger concentration of the t'-phase resulted in a higher microhardness and elastic modulus. Owing to its superior mechanical properties, fine grains and high density, REYSZ exhibited improved cavitation erosion resistance. Particularly, NdYSZ exhibited 12.4 times higher cavitation-erosion resistance than that of YSZ. Furthermore, the grain boundaries of YSZ contain special m-phase bands, which are also responsible for the quicker exfoliation of grains during cavitation erosion. The segregation of rare earth elements at the grain boundaries inhibited the generation of m-phase bands, resulting in a longer cavitation erosion incubation period for REYSZ.