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3923 |
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Friday, May 23, 2014, Hall H3 2:40 PM Medical Industry 2 / Metal Coatings |
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Improvement of delamination resistant properties for thermal barrier coating by formation wedge-like thermal grown oxide |
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Shun Hatta* / Tohoku University, Japan Kazuhiro Ogawa / Tohoku University, Japan Toshio Takanezawa/ Tohoku Electric Power, Japan Hiroyuki Yamazaki/ Tohoku Electric Power, Japan |
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In recent years, due to the demand for saving energy and reducing greenhouse gases, thermal power plants are required to be higher efficiency by increasing turbine inlet gas temperature. Therefore, it is necessary to improve delamination resistant properties of thermal barrier coatings (TBC). In our previous studies, it has reported that, by using Ce content bond coat, wedge-like thermal grown oxide (TGO) was formed at interface, and then delamination resistant properties of the TBC was improved. At this time, it was observed that wedge-like TGO grew toward CeO2, which formed in the bond coat under high temperature environment. Hence, it is thought that the wedge-like TGO was formed and grew up, because CeO2 became oxygen ion diffusion pass. However, the wedge-like TGO can be formed more than 1100, which is higher operation temperature of real plants. In this study, in order to obtain the wedge-like TGO, pre-oxidation was carried out for 20h at 1100. And then high temperature exposure tests were conducted for 1000h at 1000. As a result, the growth of the wedge-like TGO was confirmed under 1000, and isolated CeO2 had formed sufficiently in the bond coat by pre-oxidation. Furthermore, the interface strength between top coat and bond coat was evaluated by four point bending tests. As a result, the TBC with wedge-like TGO had obvious interface strength than that of the TBC without wedge-like TGO. |