Micro-indentation method for evaluation of fracture toughness and thermal residual stresses of SiC coating on carbon/carbon composite

摘要

Carbon/carbon composites are frequently used with SiC coating so as to improve their oxidation resistance. This oxidation protection coating has a thickness of about 100 mum, so that the properties of the coating might be different from those of bulk materials. However, it is rather difficult to determine mechanical properties of coatings by the usual procedures. In the present paper, a microindentation method was adopted to determine the fracture toughness and thermal residual stresses of SiC coatings. It was concluded that fracture toughness can be evaluated if the indentation load is sufficiently low, and thermal residual stress can be roughly determined, though scattering of the latter was large. [References: 18]