Influence of stabilizers on hydrothermal behavior of zirconia coatings by APS

Abstract

In recent years, the degradation of zirconia in a humid environment has attracted the attention of researching. In this work, Mg0.09Zr0.91O1.91 (MSZ), Y0.09Zr0.91O1.955 (YSZ) and Ce0.09Zr0.91O2 (CSZ) powders were prepared by co-precipitation method, the corresponding zirconia coatings were fabricated by atmospheric plasma spraying (APS). All coating samples were subjected to hydrothermal treatment to investigate their degradation process in moisture. The evolution of phase composition and microstructure were characterized. Results show that the content of monoclinic phase (m) in MSZ, YSZ and CSZ coating samples increased after hydrothermal treatment, rising by 47 % in MSZ coating, by 31 % in YSZ coating and by 8 % in CSZ coating. The degradation of internal structure of coatings was more serious with the prolongation of hydrothermal treatment time. This is because different stabilizers will cause different oxygen vacancy concentration in the zirconia unit cell, which determines the hydrothermal stability of zirconia. Under the tested condition, CSZ has the lower oxygen vacancy concentration (4 %) than MSZ (11 %) and YSZ (7 %), exhibiting better hydrothermal stability.