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Title Thermophysical properties of YSZ and YCeSZ suspension plasma sprayed coatings having different microstructures
Posted by Rolando Candidato Jr.
Authors Paweł Sokołowski, Stefan Björklund, Radek Musalek, Rolando T. Candidato,Jr., Lech Pawłowski, Benoit Nait-Ali, David Smith
Publication date 2017/02/21
Journal Surface & Coatings Technology
Volume Volume 318
Pages 11
Publisher Elsevier
Abstract The paper describes the ceramic top coats of Thermal Barrier Coatings (TBC) obtained by Suspension Plasma Spraying (SPS). The spray process realized with different plasma torches allowed obtaining coatings having different morphology, namely, columnar-like and two-zones microstructure. The microstructures influenced the thermal transport properties of TBC's. The study analyses the thermophysical properties of yttria and yttria-with ceria- stabilized zirconia coatings, i.e. YSZ and YCeSZ, respectively. The spray processes were realized with the use of three different plasma spray torches: (i) SG-100; (ii) Axial III and (iii) hybrid WSP one. The deposition parameters were designed for each plasma torch separately. The microstructure of coatings was then analyzed using Optical and Scanning Electron Microscopy i.e.OMand SEM, respectively. The thermophysical properties of the coatings such as density, specific heat and thermal dilatation were measured using gas pycnometry, calorimetry and dilatometry methods respectively. The collected datawere used, togetherwith thermal diffusivity foundwith the use of laser flashmethod, to calculate the thermal conductivity of the deposits. The thermal conductivities of coatings were in a range from 0.63 to 0.99 [W/m·K] for YSZ samples and between 0.82 and 1.37 [W/m·K] in the case of YCeSZ coatings. Thermal transport properties were found to be influenced by the coatings' porosity and their microstructure. Finally, the thermal conductivity values were successfully validated using response function method, which can be an alternative to complex FEM methods.
Index terms / Keywords Thermal Barrier Coatings (TBC) Suspension Plasma Spraying Thermal conductivity Specific heat Thermal dilatation Response function method