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5230 |
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YSZ/Al2O3/SiC composite coatings obtained by suspension plasma spraying |
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Eugeni Cañas / Universitat Jaume I, Spain Mónica Vicent / Instituto de Tecnología Cerámica (ITC), Asociación de Investigación de las Industrias Cerámicas (AICE), Universitat Jaume I (UJI), Spain María José Orts/ Instituto de Tecnología Cerámica (ITC), Asociación de Investigación de las Industrias Cerámicas (AICE), Universitat Jaume I (UJI), Spain Rodrigo Moreno/ Instituto de Cerámica y Vidrio (ICV), Consejo Superior de Investigaciones Cerámicas (CSIC), Universidad Autónoma de Madrid, Spain Enrique Sánchez*/ University Jaume I, Spain |
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Plasma sprayed thermal barrier coatings (TBCs) are widely used in the hot section of turbines and aero-engines, protecting these parts from high temperature corrosion and oxidation. Conventional TBCs are mainly based on a ceramic coating of yttria-stabilized zirconia (YSZ). However, the useful life of these coatings is limited due to thermal fatigue which results in substrates oxidation and, therefore, coatings delamination. An interesting approach to overcome this drawback deals with the design of a new composite TBC in which a second phase with self-healing functionality can be added to a YSZ matrix. SiC is the most common ceramic material showing self-healing property. However, preservation of the self-healing functionality after plasma deposition of SiC particles certainly represents a big challenge. Consequently, the aim of the present work is to develop preliminary thermal barrier coatings by suspension plasma spraying (SPS) with a potential self-healing functionality provided by SiC particles dispersed in a YSZ matrix. First of all, an aqueous suspension was prepared and then stabilised to be used as feedstock in the development of the ceramic composite coating. The suspension was composed of submicron powder of 4YSZ (which acts as thermal insulator), SiC (which acts as sealing agent) and Al2O3 (which prevents the substrate oxidation). Feedstock characteristics as well as plasma spray conditions were varied so as to minimise SiC oxidation during plasma spraying. X-ray diffraction and SEM examination of the obtained coatings revealed a quite homogeneous microstructure made up of unmelted SiC particles dispersed in a sintered, partially melted YSZ matrix. This work has been supported by the Spanish Ministry of Economy and Competitiveness (MAT2015-67586-C3-1-R). |