Novel Fabrication of Porous Ni-5 wt.% Al Alloy Electrode Below the Melting Point of Aluminum

Abstract

An in-situ sintered Ni-5 wt.% Al alloy anode for high-temperature fuel cells (HTFCs) was fabricated successfully using a green sheet consisting of a physical mixture of inexpensive Ni and Al elemental powders at reduced temperatures. Two processes-the formation of Ni-Al alloy via the AlCl3 activator under flowing hydrogen gas and the sintering of Ni-Al-occurred at the same time during pretreatment for cell operation. The AlCl3 activator reduced the synthesis reaction temperature and sintering temperature of Ni-Al alloy to nearly 600 degrees C. A two-phase alloy of a Ni3Al intermetallic compound and a Ni-Al solid solution was obtained after sintering at 600 degrees C. The creep resistance of the in-situ sintered Ni-5 wt.% Al alloy was better than that of the conventional Ni-Al alloy green sheet, even though the sintering temperature of the Ni-5 wt.% Al alloy was 600 degrees C. This novel preparation method for Ni-Al alloys can greatly reduce the cost of anode fabrication for HTFCs and in turn accelerate the commercialization of HTFCs.