著者

Son Thanh NGUYEN Tsuyoshi TAKAHASHI Ayahisa OKAWA Hisayuki SUEMATSU Koichi NIIHARA Tadachika NAKAYAMA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.129, no.4, pp.209-216, 2021-04-01 (Released:2021-04-01)

参考文献数

33

被引用文献数

12

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In the emerging era of aircraft industry, silicon carbide (SiC) is regarded as an appropriate material for gas turbine engine blades. In order to protect this ceramic component against the oxidation and volatilization in hot steam environments, environmental barrier coating should be utilized. The composite of SiC/Yb2Si2O7–Yb2SiO5 with self-healing ability is a candidate for the top layer of this coating. In this study, the crack-healing behavior of SiC/Yb2Si2O7–Yb2SiO5 nanocomposites is investigated by pre-cracking followed by annealing in oxidizing environments. Comparing to previous studies, the healing time and healing temperature can be reduced to 15 min and 800 °C by increasing the volume fraction of SiC to 20 %. In addition, nanocomposites with both self-healing ability and superior strength were created in this research by combining two types of SiC filler (whiskers and nanoparticulates). The self-healing mechanism in these composites is the SiC oxidation and silicate transformation associated with their volume expansion, which is evidenced by X-ray diffraction and scanning electron microscope. According to the results, the best volume ratio between whisker and nanoparticulate is determined as 1/3.

著者

Son Thanh Nguyen Tadachika Nakayama Masatoshi Takeda Nguyen Ngoc Hieu Tsuyoshi Takahashi

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.61, no.8, pp.1510-1516, 2020-07-01 (Released:2020-07-25)

参考文献数

32

被引用文献数

4

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Thermal barrier coatings (TBCs) are necessary to protect nickel-based alloy blades of gas turbine against oxidation and thermal fatigue in high-temperature operating conditions. Ceramic materials, which are very good natural thermal insulator, attract the most interests from engineers and scientists. However, the brittleness of ceramics is a major obstacle for utilizing them as the TBCs, which are also required very good damage tolerance against physical impacts. The cracks appear on the blade surfaces during its operation can lead to the severe failure. In this research, a composite of Y2Ti2O7 and Ni was developed as a self-crack healing material to overcome this problem. The crack-healing behavior is investigated by using Vickers indenter to create cracks on the composite surface intentionally, followed by annealing in an oxidizing environment. It is found that the main crack-healing mechanism is the filling of NiO, which was formed from the oxidation of the Ni fillers, into the cracks. Complete heal of cracks is achieved with 10 vol% Ni filler, which is confirmed by X-ray diffraction and scanning electron microscopy. Thermal conductivity and Weibull distribution for the strength of the composite were also investigated to find the appropriate volume fraction of Ni nanoparticles in this self-healing material.