MICROSTRUCTURAL AND PHASE STABILIZATION EFFECTS OF METAL OXIDE CO-DOPANTS ON 7YSZ THERMAL BARRIAR COATINGS

摘要

Standard 7 wt% yttria stabilized zirconia (7YSZ) was co-doped with ytterbia, ceria and niobia to investigate the phase stabilization effect of ionic properties, oxygen vacancies and varied cooling rates. Cold pressed and sintered samples were furnace, air or fan cooled, and cooling rate was confirmed to predictably influence the phase transformations. Quantitative analyses indicated that ytterbia exhibited the most effect in stabilizing high temperature phases, followed by ceria. Niobia destabilized high temperature phases and supported predictions regarding the influence of oxygen vacancies. Sintered relative densities were calculated to be greater than 93% and pore volumes ranged between 7 and 16%.