Measurement of Bonding Strength of Plasma-Sprayed Thermal Barrier Coatings by a Modified Four-Point-Bending Method

摘要

In this study, the adhesion of thermal barrier coatings 8YSZ (ZrO_2+8wt%Y_2O_3) deposited on NiCrA1Y bond-coat by atmospheric plasma spraying is investigated experimentally. A modified four-point-bend specimen that has only one interface crack to facilitate the control of crack growth is adopted for the tests. The load-displacement curves obtained show two stages of crack initiation and stable crack growth. Examination show that crack initiates along the interface YSZ/NiCrA1Y and grows within YSZ layer. Based on a microstructural model, finite element analyses are performed to extract the bonding strength of the TBCs.