The effect of oxygen pressure in active brazing 8YSZ and Crofer 22H alloy

Abstract

The study focused on the effects of oxygen pressure on active brazing of 8YSZ and Crofer 22H alloy using Ticusil filler metal. The presence of oxygen had a strong effect on the bonding mechanism at the interface between the 8YSZ and the Ticusil filler metal. In the joint brazed at 900 °C for 600 s in air, a continuous TiO2 reaction layer with a thickness of approximately 3 μm was observed at the interface between the 8YSZ and the Ticusil filler metal. In the joint brazed at 900 °C for 600 s under high vacuum of 5 × 10−3 Pa, the interface between the 8YSZ and the filler metal changed into two different reaction layers comprising Ti3O, and the brazing alloy was not oxidized in the vacuum environment. The presence of oxygen during active brazing has significantly changed the interfacial reaction between the 8YSZ and the filler metal.

Keywords

• Active brazing
• Fuel cell
• Interfacial reaction
• Microstructure