THERMAL SHOCK FATIGUE EVALUATION OF FGM BY AE TECHNIQUE/

This study has been carried out to analyze the thermal shock and fatig ue characteristics of functionally gradient material (FGM). The therma l shock/fatigue tests were conducted at a specific temperature and fra cture patterns were studied by SEM and AE. Also, thermal fracture beha vior of plasma-sprayed FGM and conventional coating material (NFGM) wa s examined by acoustic emission technique under heating and cooling. F urnace cooling and air cooling tests were used to examine the effect o f temperature change under various conditions. The conventional and FG M coatings were compared to heat-resistant property and fracture surfa ce of these materials for each temperature history. Based on these res ults, some critical temperature at the onset of coating failure can be evaluated to characterize the thermal resistance of the materials. It turned out to be that FGM gives higher thermal property compared with NFGM by AE signal and fracture surface analysis.