Elastic and Inelastic Deformation Properties of Free Standing Ceramic EB-PVD Coatings

A method for in situ measurement of the elastic behavior of a columnar thermal barrier coating

“…The magnitude of the inplane TBC modulus was determined to be in the range of 15-30 GPa. These values fall well within the broad range of values previously obtained using compression testing of free-standing cylindrical coatings (10-26 GPa) [3], flexural resonance (10-80 GPa) [2], mechanical spectroscopy (22 GPa) [14] and indentation techniques (60-170 GPa) [15,16]. The in-plane modulus of EBPVD 7YSZ coatings have been reported to depend on the residual stress in the coating, with the highest in-plane modulus being observed in coatings deposited with high compressive stresses [2].…”

“…5c) show that the magnitude of the strain in the TBC scaled with applied load, while the neutral axis did not. The observation that the normalized data sets from the beam center and shoulder both collapse to universal curves indicates that the compliance of the microbeams measured in this study, and thus the in-plane modulus of the TBC, does not depend on strain as has previously been reported [2][3][4].…”

“…Attendant changes in properties, namely the elastic properties, will play an important role in determining the performance and durability of the coating but are difficult to measure and remain to be elucidated. Moreover, microstructural variations across the thickness of the TBC could lead to a positiondependent modulus and the feathery nature of the columns have led some investigators to report that the in-plane modulus, E p , depends on the imposed in-plane strain, e xx [2][3][4]. Here, the proposed microbending experiments are employed to characterize as-deposited coatings, but investigations involving microstructural evolution and other second-order effects are also practicable.…”