Induction brazing for gas sealing of anode-supported tubular solid oxide fuel cells using the nickel based brazing alloy modified by TiH2

The nickel based brazing alloys (BNi 2, BNi 4) modified by reactive TiH2 have been studied for their gas sealing properties of anode-supported tubular SOFCs to ferritic stainless steel by induction brazing process. BNi 2 and BNi 4 are not wetted on YSZ electrolyte, but the brazing alloy with TiH2 showed good wettability with YSZ electrolytes due to a formation of TiOx layer. Among the tested brazing alloys (BNi 2, BNi 4, modified BNi 2, modified BNi 4), all except modified BNi 4 did not join with YSZ. The modified BNi 4 showed the lowest gas leak rate. The gas tightness of a brazed cell was confirmed by open circuit voltage, which was nearly the same as a theoretical value. Based on these experimental results, it is concluded that the BNi 4 modified by TiH2 is suitable as a sealing material in SOFCs operating at 750 °C.