Evaluation on Thermomechanical Properties of Functionally Gradient Materials with High Temperature Gradients

The Fuctionally Gradient Materials(FGM) comprise with different material components such as ceramics and metals with continuously varying mixture ratio and micro structure in conformance with the actual environments in order to relax the thermal stress due to high temperature gradients. This evaluation method was developed to determine the performance of the FGM related with thermal resistance and thermal fatigue. High temperature gradient condition was accomplished by heating one side of specimen with Xenon lamp while cooling the other surface with liquid hydrogen or nitrogen in vacuum. The evaluation of the samples were available for metallographic examination and the variation of the effective thermal conductivity dependent upon the delamination damage and subcritical cracks. Some samples fabricated by several method were examined under several conditions. With some results that it was evident the FGM was quite promising for decreasing the thermal stress under high heat loads.