Reactive air brazing (RAB) is a low-cost process for joining ceramic composites in air. However, due to the comparably low strength values that can be achieved by RAB, the process is only used in special applications like solid oxide fuel cells as a sealant. The limited strength values are the result of a severe pore formation during the brazing operation that remain in the brazing fillet after the solidification of the brazing filler. In this work, the formation of the pores during RAB brazing of alumina using a paste containing Ag4CuO powder and various binders was investigated. The formation and evolution of the pores were observed and quantified in in situ X-ray measurements. It could be observed that during debinding, pores have developed in the filler metal. The pore structure depends on the binder and the heating rate in the debinding stage. With the melting of the filler metal, many pores are closed by the melt flow. But it seems that the wetting of the alumina was hindered by the pores. The change of porosity during cooling is comparatively low.

反应空气钎焊 (RAB) 是一种在空气中连接陶瓷复合材料的低成本工艺。然而，由于 RAB 可实现的强度值相对较低，因此该工艺仅用于特殊应用，例如作为密封剂的固体氧化物燃料电池。有限的强度值是由于在钎焊操作过程中形成严重的气孔而导致的，这些气孔在钎焊填料凝固后保留在钎焊焊角中。在这项工作中，研究了使用含有 Ag4CuO 粉末和各种粘合剂的糊剂对氧化铝进行 RAB 钎焊期间孔的形成。通过原位 X 射线测量观察并量化了孔隙的形成和演变。可以观察到，在脱脂过程中，填充金属中出现了孔隙。孔结构取决于粘合剂和脱脂阶段的加热速率。随着填充金属的熔化，许多孔隙被熔体流动封闭。但孔隙似乎阻碍了氧化铝的润湿。冷却过程中孔隙率的变化相对较小。