Abstract
Thermal barrier coatings (TBCs) of 8wt% yttria-zirconia were made by air plasma-spraying (APS) and by low-pressure plasma-spraying (LPS). TBCs were removed from substrates, and the specimens were prepared as free-standing thin films. The mechanical and X-ray elastic constants were measured under both tensile and bending deformations, where a specially designed jig was used for tensile tests. The value of the mechanical Young's modulus of APS films measured by tensile loading was close to that by bending. On the other hand, the value of mechanical Young's modulus of LPS films measured by bending was nearly half of that by tensile loading. The difference in the mechanical elastic constant between APS and LPS films were mainly comes from the difference in lamella structures. The X-ray elastic constants determined for both films were nearly identical, independent of the deformation mode. Using the measured values of X-ray elastic constants, the residual stress distribution of TBCs with the substrate was determined.
