Residual stress analysis of Ti–ZrO2 thermal barrier graded materials

Elastic finite element numerical models are used to study the steady-state thermal stresses induced on cooling from the sintering temperature of Ti–ZrO2 thermal barrier functionally graded materials (FGMs). The mechanical and thermal properties of Ti–ZrO2 composites with different Ti volume fractions are calculated by rule-of-mixtures. For a disk-shaped specimen with a linear compositional distribution and a fixed geometric size, optimum microstructural characteristics for minimizing residual stress are identified. The theoretical analysis and experimental results show that the stress concentration is built up near the graded-layer-interface. The radial stress preferentially acts on the fracture of FGMs. This is in agreement with the experimental results. The graded structure of FGMs can greatly reduce the residual stress compared with non-graded interface of directly jointed materials. To predict the performance of Ti–ZrO2 FGMs which is served in the conditions with large temperature difference, the thermal stress distribution in the temperature field has also been analyzed.