STRESS STATE AND FAILURE MECHANISMS OF THERMAL BARRIER COATINGS: ROLE OF CREEP IN THERMALLY GROWN OXIDE

摘要

The mechanical loading of the thermal barrier coating(TBC)/thermally grown oxide(TGO)/bond coat interface region is calculated for a TBC coated superalloy specimen using a finite element model. It is shown that the evolving stress state depends crucially on the radio of the loading rate caused by growth and swelling of the oxide layer and the unloading rate by creep relaxation. For grain sizes below 1μm, creep of the oxide layer cannot be neglected.