Residual Stress in NiO-YSZ Composites and Its Relationship to Microstructure

Abstract

Residual stress in NiO-YSZ was numerically simulated using 2D models consisted of the arrays of NiO and YSZ particles to evaluate the influence of thermal stress due to the large difference of thermal expansion coefficient between NiO and YSZ. The influence of geometric microstructure changed by fabrication processes was also evaluated using the models with different arrangements. Numerical simulation revealed that thermal strain introduced from the hetero interfaces was canceled each other, and residual stress in a uniform model was small. But, in ununiformed models, residual stress increased because counterpart stress was absence at homo interfaces due to ununiformity. Simulation results also indicated that a part of particles near the interfaces was exposed to high residual stress as reaction forces to thermal stress.