W. Chi, State University of New York -Stony Brook, Stony Brook, NY; S. Sampath, State University of New York, Stony Brook, NY; H. Wang, High Temperature Materials Laboratory, Oak Ridge, TN
New demands arising from the automotive and aerospace industries now require considerable achievement of the reliability and stability control for thermal barrier coatings (TBCs). The development of accurate measurement method provides a reliable tool for the study of property stability. In this work, yttria-stabilized zirconia (YSZ) coatings were manufactured at similar particle state with the selection of feedstocks, and the thermal conductivity repeatability was examined by xenon flash technique in collaboration with the Oak Ridge National Laboratory (ORNL). The particle diagnostic of cross session was observed by secondary electrons SEM. The variations of microstructural features of the TBCs were characterized by image analysis complemented with Archimedes’ method and used to interpret the stability of thermal transport property. All the efforts aim to achieve the enhancement of the stability and reliability of the coatings for prolonging lifetime of components, as well as establish a knowledge base on their intrinsic materials properties and behavior.
Summary: TBCs deposited by plasma spraying in air are known to be structurally complex due to the stochastic nature of coating built-up process, and the structural features have a significant effect on thermal transport. The complexities of the microstructures associated with processing involving a large number of interrelated variables offer a great challenge of “primary reliant”. Aside from inherent complexity of plasma spray process, the other major obstacle to control coating stability results from the fidelity of measurement technique for property. In this study, we adopted an advanced and precise measurement technique (xenon flash technique) to examine the stability and reliability of the thermal transport property of TBCs. The undulations of property were elucidated from the point view of microstructure. This study gives a clue to achieve higher degree control for stability and reliability of coatings.
