Nickel Grain Growth Inhibition with Ni₃Al Intermetallics in Porous MCFC Anode

Abstract

The effect of Ni₃Al on nickel grain growth inhibition is investigated during the sintering process of a Ni-based porous molten carbonate fuel cell (MCFC) anode including 4 to 10 wt% fine Ni₃Al intermetallic particles. Nickel grain growth is retarded and the grains are kept the proper size due to the pinning effect of Ni₃Al intermetallics that control nickel grain boundary movement, and due to the dominant surface diffusion in the vicinity of necks formed between nickel powders. It is found that the nickel grain growth rate of the anode including Ni₃Al intermetallics follows the kinetics law; G^m – G_o^m = Kt with m = 4.5, in which the grain size exponent is higher than that of porous pure nickel anode. A pore size distribution in the anode ranges from 3 to 6 μm, which is compatible with the electrochemical reaction of the MCFC.