Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
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Evaluation of the Degradation of a 1300℃-class Gas Turbine Blade by a Coating Analysis

1300℃급 가스터빈 1단 블레이드의 코팅분석을 이용한 열화평가

  • Song, Tae Hoon (Korea Electric Power Research Institute, Power Generation Laboratory) ;
  • Chang, Sung Yong (Korea Electric Power Research Institute, Power Generation Laboratory) ;
  • Kim, Beom Soo (Korea Electric Power Research Institute, Power Generation Laboratory) ;
  • Chang, Jung Chel (Korea Electric Power Research Institute, Power Generation Laboratory)
  • 송태훈 (한전전력연구원 수화력발전연구소) ;
  • 장성용 (한전전력연구원 수화력발전연구소) ;
  • 김범수 (한전전력연구원 수화력발전연구소) ;
  • 장중철 (한전전력연구원 수화력발전연구소)
  • Received : 2010.05.11
  • Published : 2010.10.22
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Abstract

The first stage blade of a gas turbine was operated under a severe environment which included both $1300^{\circ}C$ hot gas and thermal stress. To obtain high efficiency, a thermal barrier coating (TBC) and an internal cooling system were used to increase the firing temperature. The TBC consists of multi-layer coatings of a ceramic outer layer (top coating) and a metallic inner layer (bond coat) between the ceramic and the substrate. The top and bond coating layer respectively act as a thermal barrier against hot gas and a buffer against the thermal stress caused by the difference in the thermal expansion coefficient between the ceramic and the substrate. Particularly, the bondcoating layer improves the resistance against oxidation and corrosion. An inter-diffusion layer is generated between the bond coat and the substrate due to the exposure at a high temperature and the diffusion phenomenon. A thickness measurement result showed that the bond coat of the suction side was thicker than that of the pressure side. The thickest inter-diffusion zone was noted at SS1 (Suction Side point 1). A chemical composition analysis of the bond coat showed aluminum depletion around the inter-diffusion layer. In this study, we evaluated the properties of the bond coat and the degradation of the coating layer used on a $1300^{\circ}C$-class gas turbine blade. Moreover, the operation temperature of the blade was estimated using the Arrhenius equation and this was compared with the result of a thermal analysis.

Keywords

Acknowledgement

Supported by : 한국에너지기술평가원(KETEP)

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