IN SITU MICRO-SCALE EXPERIMENTS FOR MEASURING THE INTERFACIAL TOUGHNESS OF YTTRIA STABILIZED ZIRCONIA THERMAL BARRIER COATINGS

摘要

Multilayered thermal barrier systems offer tremendous technological advantages but must remain attached to the substrate to be effective.Important phenomena that affect delamination occur in each layer and at the interfaces between the different materials.This talk will detail the development and use of micro-bending experiments undertaken to measure the elastic modulus of physical vapor deposited (PVD) 7-YSZ thermal barrier coatings.The use of digital image correlation (DIC) to measure the spatial displacement fields associated with the application of point loads will be coupled with a detailed finite element (FE) model of the micro-bending specimen and used to deduce the strain dependence of the in-plane modulus.The DIC displacement field also allows for direct observation of crack nucleation and propagation and precise determination of the crack tip as a function of applied load.Comparisons with FE simulations allow for determination of the inter-columnar YSZ fracture toughness and the interfacial toughness between the YSZ and the underlying thermally grown oxide.