한국재료학회지 제27권 제3호 (p.155-160)

플라즈마 스프레이 (Ca, Co)-Doped LaCrO3 코팅층의 치밀화 및 전기전도도

키워드 :
LaCrO3 interconnect,plasma spraying,microstructural defects,gas tightness,electrical conductivity.

초록

Doped-LaCrO3 perovskites, because of their good electrical conductivity and thermal stability in oxidizing and/or reducing environments, are used in high temperature solid oxide fuel cells as a gas-tight and electrically conductive interconnection layer. In this study, perovskite (La0.8Ca0.2)(Cr0.9Co0.1)O3 (LCCC) coatings manufactured by atmospheric plasma spraying followed by heat treatment at 1200 oC have been investigated in terms of microstructural defects, gas tightness and electrical conductivity. The plasma-sprayed LCCC coating formed an inhomogeneous layered structure after the successive deposition of fully-melted liquid droplets and/or partially-melted droplets. Micro-sized defects including unfilled pores, intersplat pores and micro-cracks in the plasma-sprayed LCCC coating were connected together and allowed substantial amounts gas to pass through the coating. Subsequent heat treatment at 1200 oC formed a homogeneous granule microstructure with a small number of isolated pores, providing a substantial improvement in the gas-tightness of the LCCC coating. The electrical conductivity of the LCCC coating was consequently enhanced due to the complete elimination of inter-splat pores and microcracks, and reached 53 S/cm at 900 oC.