Thermal cycling and reactivity of a MoSi_2/ZrO_2 composite designed for self-healing thermal barrier coatings

摘要

Consolidated (relative density of 84%) composite made of molybdenum di-silicide (MoSi_2) particles dispersed in a yttria partially stabilized zirconia matrix (8Y_2O_3-ZrO_2) was prepared by spark plasma sintering. Cyclic oxidation of the composite at temperature ranging from 1000 ℃ to 1300 ℃ was studied. Parabolic rate constants (k_p) values of the composite material are in good agreement with those obtained in the literature for the oxidation of bulk MoSi_2. Following oxidation exposure, formation of Mo_5Si_3, SiO_2 and ZrSiO_4 phases was observed. These observations are compatible with the use of MoSi_2 as a self-healing agent in YPSZ thermal barrier coatings.