On the CMAS Problem in Thermal Barrier Coatings: Benchmarking Thermochemical Resistance of Oxides Alternative to YSZ Through a Microscopic Standpoint
| Autor: | Çağan Berker İyi, Martha Mecartney Daniel R. Mumm |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | International Journal of Innovative Approaches in Science Research. 3:20-40 |
| ISSN: | 2602-4535 2602-4810 |
| DOI: | 10.29329/ijiasr.2019.197.1 |
| Popis: | This study focuses on experimental modelling of the failure of Thermal Barrier Coatings (TBCs) due to attack of CMAS (Calcia-Magnesia-Alumina-Silicate), which is often found in harsh environments, via glassy phase infiltration. Volcanic ash and dust, sand particles, and fly ash, which contain CMAS, are imminent threats impeding predictable lifetimes of TBCs. Such incurrence directly affects the geometry and clinging to bond coat, and intrinsic material properties such as thermal conductivity and crystal structure of TBC are modified after exposure to CMAS, which ultimately results in delamination, spallation and failure of the coating material. The scope of this work is to survey the reactivity of CMAS with various oxide systems, and evaluate possible oxide systems that can be replaced and/or used with Yttria-stabilized Zirconia (YSZ) by investigating the penetration depth and reactivity after sintering with CMAS. A cost-effective method to observe the reaction of candidate oxides with CMAS is suggested and administired; understanding the main mechanism that causes the failure of top coat in the wake of CMAS infiltration, and seeking solutions for the problem is performed by taking advantage of Scanning Electron Microscopy (SEM). Recently suggested ceramic oxide systems that form in pyrochlore structure, some perovskite structures in various compositions, monazite, mullite and YSZ are studied. The possible outcome consequent upon CMAS infiltration are concluded and course for designing novel material systems that are expected to withstand the CMAS attacks better than the state-of-the-art 4mole% YSZ is defined. 5% mole Yb-doped SrZrO3(5Yb-SZ) and favored pyrochlores such as Gd2r2O7 and GdYbZr2O7 are found to be better mitigating CMAS attacks. |
| Databáze: | OpenAIRE |
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