Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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Thermal Evolution of BaO-CuO Flux as Sintering Aid for Proton Conducting Ceramic Fuel Cells

  • Biswas, Mridula (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Hong, Jongsup (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Kim, Hyoungchul (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Son, Ji-Won (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Lee, Jong-Ho (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Kim, Byung-Kook (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Lee, Hae-Weon (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology) ;
  • Yoon, Kyung Joong (High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology)
  • Received : 2016.08.24
  • Accepted : 2016.09.21
  • Published : 2016.09.30
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Abstract

The eutectic melt of BaO-CuO flux is known to be a potential sintering aid for $Ba(Zr,Y)O_3$ (BZY) electrolyte for proton-conducting ceramic fuel cells (PCFCs). A density of BZY higher than 97% of theoretical density can be achieved via sintering at $1300^{\circ}C$ for 2 h using a flux composed of 28 mol% BaO and 72 mol% CuO. In the present study, chemical and structural evolution of BaO-CuO flux throughout the sintering process was investigated. An intermediate holding step at $1100^{\circ}C$ leads to formation of various impurity compounds such as $BaCuO_{1.977}$, $Ba_{0.92}Cu_{1.06}O_{2.28}$ and $Cu_{16}O_{14.15}$, which exhibit significantly larger unit cell volumes than the matrix. The presence of such secondary compounds with large lattice mismatch can potentially lead to mechanical failure. On the other hand, direct heating to the final sintering temperature produced CuO and $Cu_2O$ as secondary phases, whose unit cell volumes are close to that of the matrix. Therefore, the final composition of the flux is strongly affected by the thermal history, and a proper sintering schedule should be used to obtain the desired properties of the final product.

Keywords

References

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