Determination of interfacial fracture toughness of coatings using circumferentially notched cylindrical substrate

► Interfacial fracture toughness was evaluated using circumferentially notched tensile specimens (CNT). ► Interfacial fracture toughness of coated materials was evaluated as a function of mode mixity. ► A well defined pre-crack was introduced at the interface of a coating-substrate system. ► The results showed an increase in the interfacial fracture toughness with an increase in phase angle. ► CNT specimens are shown to be capable of producing reputable results of interfacial fracture toughness.