Creep mechanism of porous MCFC Ni anodes strengthened by Ni3Al

Creep tests were conducted to measure the creep rates of pure Ni, Ni/7wt%Ni3Al, and Ni/5wt%Ni3Al/5wt%Cr anodes for MCFCs. The resulting creep rates were well modeled by a creep rate equation. During the initial stage of sintering, the creep mechanism was affected by the microstructure, and geometry referred to the macroscopic shapes of the porous anodes. For the Ni/7wt%Ni3Al and Ni/5wt%Ni3Al/5wt%Cr anodes, the creep rate varied nonlinearly with time, obeying a power law with an exponent of n < 1, in contrast to the behavior of high-density materials, which exhibit linear Nabarro-Herring or Coble creep when subjected to an applied load. Compared to the pure Ni anode, the anodes containing Ni3Al showed considerably increased creep resistance due to the impeding of mass transport of nickel particles in the anode when it was subjected to a compressive load. Collectively, the present results suggest that Ni/7wt%Ni3Al and Ni/5wt%Ni3Al/5wt%Cr anodes simultaneously have high creep resistance, and thus may represent a viable alternative porous anode for use in MCFC. © 2005 American Institute of Chemical Engineers AIChE J, 2006