Tailoring the EB-PVD columnar microstructure to mitigate the infiltration of CMAS in 7YSZ thermal barrier coatings |
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| Affiliation: | 1. Department of Mechanical Engineering, University of California, Santa Barbara, 93106-5070, United States;2. Materials Department, University of California, Santa Barbara, 93106-5070, United States;1. School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, China;2. Key Laboratory of Low Dimensional Materials & Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105, China;3. Department of Mechanical Engineering & Materials Science and Engineering Program, State University of New York, Binghamton, NY 13902, USA |
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| Abstract: | The CMAS associated degradation of 7YSZ TBC layers is one of the serious problems in the aero engines that operate in dusty environments. CMAS infiltrates into TBC at high temperatures and stiffens the TBC which ultimately loses its strain tolerance and gets delaminated. The EB-PVD technique is used to coat TBCs exhibiting a columnar microstructure on parts such as blades and on vanes. By varying the EB-PVD process parameters, columnar morphology and porosity of the 7YSZ coating is changed and its effect on the CMAS infiltration behaviour is studied in detail. Two different TBC pore geometries were created and infiltration experiments were carried out at 1250 °C and 1225 °C for different time intervals. The 7YSZ coating with more ‘feathery’ features has resulted in higher CMAS resistance by at least by a factor of 2 than its less ‘feathery’ counterpart. These results are explained on the basis of a proposed physical model. |
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| Keywords: | CMAS Thermal barrier coatings 7YSZ Infiltration EB-PVD coatings |
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