- Morphologies of Brazed NiO-YSZ/316 Stainless Steel Using B-Ni2 Brazing Filler Alloy in a Solid Oxide Fuel Cell System
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Sung-Kyu Lee, Kyoung-Hoon Kang, Hyun-Seon Hong, Sang-Kook Woo
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J Korean Powder Metall Inst. 2011;18(5):430-436.
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DOI: https://doi.org/10.4150/KPMI.2011.18.5.430
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 Abstract
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- Joining of NiO-YSZ to 316 stainless steel was carried out with B-Ni2 brazing alloy (3 wt% Fe, 4.5 wt% Si, 3.2 wt% B, 7 wt% Cr, Ni-balance, m.p. 971-999°C) to seal the NiO-YSZ anode/316 stainless steel interconnect structure in a SOFC. In the present research, interfacial (chemical) reactions during brazing at the NiO-YSZ/316 stainless steel interconnect were enhanced by the two processing methods, a) addition of an electroless nickel plate to NiO-YSZ as a coating or b) deposition of titanium layer onto NiO-YSZ by magnetron plasma sputtering method, with process variables and procedures optimized during the pre-processing. Brazing was performed in a cold-wall vacuum furnace at 1080°C. Post-brazing interfacial morphologies between NiO-YSZ and 316 stainless steel were examined by SEM and EDS methods. The results indicate that B-Ni2 brazing filler alloy was fused fully during brazing and continuous interfacial layer formation depended on the method of pre-coating NiO-YSZ. The inter-diffusion of elements was promoted by titanium-deposition: the diffusion reaction thickness of the interfacial area was reduced to less than 5 µm compared to 100 µm for electroless nickel-deposited NiO-YSZ cermet.
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