Study on Evaluation of Thermal Shock Fracture and Thermal Stress Relaxation Property of FGM by Laser Local Heating Technique

This paper presents some results of transient thermal transfer and thermal stress analyses of thermal barrier coatings subject to rapid heating. The objective of this study is to develop a laser heating test for evaluating the thermal shock resistance of functionally gradient materials (FGMs). The numerical calculations are conducted on plasma-sprayed single-layer Zro₂ (stabilized with 8% Y₂O₃), and FGM which consists of multilayer with varying mixture ratios of ZrO₂ and NiCrAlY deposited on a stainless steel substrate. The thermal barrier coatings with temperature dependent thermal and mechanical properties are heated by laser impingement. The transient thermal stress distribution is determined based on temperature profile using a finite element method. The intensity distribution within laser beam is taken into account. Based on the numerical results, the effect of the gradient composition in the FGM on the thermal shock resistance is examined. It is shown that the numerical analysis can provide a quantitative description of the enhanced thermal shock resistance of the FGM.