Microstructure characteristics of EB-PVD perovskite thermal barrier coatings

Reference Presenter Authors
(Institution)
Abstract
14-089 Bogdan S. Vasile Vasile, B.S.(Polytechnical University, Faculty of Appl. Chem.& Mater. Science); Surdu, V.A.(University POLITEHNICA of Bucharest); Birca, A.(Polytechnical University, Faculty of Appl. Chem.& Mater. Science); Vasile, O.R.(Polytechnical University, Faculty of Appl. Chem.& Mater. Science); Andronescu, E.(Polytechnical University, Faculty of Appl. Chem.& Mater. Science); Trusca, R.(Polytechnical University, Faculty of Appl. Chem.& Mater. Science); Piticescu, R.R.(NATIONAL RESEARCH & DEVELOPMENT INSTITUTE FOR NON-FERROUS AND RARE METALS - I M N R); SOBETKII, A.(NATIONAL RESEARCH & DEVELOPMENT INSTITUTE FOR NON-FERROUS AND RARE METALS - I M N R); BaZrO3, NiCr bond coat/BaZrO3 and BaZrO3/La2Zr2O7 perovskite thermal barrier coatings deposited on NIMONIC using EB-PVD method were investigated in terms of structure and microstructure after deposition and after thermal shock. GI-XRD investigations proved obtaining the proposed phases but in the case of NIMONIC/BaZrO3 and NIMONIC/NiCr bond coat/BaZrO3, there is also present a decomposition of BaZrO3 and a secondary product, ZrO2 may be identified in the patterns. The deposition of a La2Zr2O7 on top of a BaZrO3 layer seems to have a beneficial effect on the stabilization of BaZrO3. FE-SEM studies revealed dendritic like structures in the case of BaZrO3 and NiCr-bond coat/BaZrO3 with grains in the range of 40-60nm. In the case of composite structure BaZrO3/La2Zr2O7, the surface is smooth and it is structured with fine grains with an average size of about 18 nm. EDS mapping showed areas in which the thin film was detached from the substrate. After thermal shock, all the samples showed that the coatings were affected depending on the temperature, first the detaching of the thin film occurring, then the melting of the substrate at the highest temperature being observed. Also, due to the increase of the temperature, a feather-like structure which is characteristic for NIMONIC and an increased porosity may be observed.
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