Interfacial Fracture Toughness Evaluatoin of Ceramic Thermal Barrier Coatings Based on Indentation Test Method
Masayuki ARAI
Abstract:In this study, the method evaluating the interfacial strength (I.e. interfacial fracture toughness) of ceramic thermal barrier coatings (TBCs) is proposed based on the indentation test method. The obtained results are summarized as following; (1) Lesage & Chicot model was applied to evaluate the interfacial fracture toughness of TBC, firstly. The results showed that the associated fracture toughness was varied with the indentation load condition, which means that Lesage & Chicot model is unsuitable to TBC interfacial strength evaluation. (2) The alternative complex stress intensity factor for evaluating TBC interfacial fracture toughness with the indentation test was introduced by assuming that the internal crack geometry induced by the indentation identifies the rectangle shape spread along the specimen surface. It was found to be able to apply the proposed equation to TBC interfacial fracture toughness evaluation. Key Words:Gas turbine, Thermal barrier coatings, Interfacial fracture toughness, Indentation test method