2021 年 62 巻 8 号 p. 1210-1215
Pure Al foams were bonded via foaming bonding using Al–10.5Si brazing alloy. However, the pores around the bonded area were coarsened because Si diffused into the Al foam from the brazing foam, where it reduced the melting temperature, leading to melting of the cell walls of the Al foam. The bonding strength of the bonded foam varied greatly. An Al–Si brazing precursor with a low Si concentration was prepared and used for foaming bonding of two Al foam specimens. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy were used to investigate the bonding state. Four-point bending tests were conducted to evaluate the bonding strength. The brazing foam was metallurgically bonded with the Al foam when brazing precursors with 9.4–10.5 mass% Si were used. The bonding interfaces were partially observed by SEM. The bonding strength of the Al foam bonded using 10.5 mass% Si brazing foam was lower than the minimum strength of the Al foam. The bonding strength of the specimen bonded using the 9.4 mass% Si brazing foam was lower than the minimum strength of pure Al foam and the bonding strength of the other bonded specimens. An Al–Si brazing precursor with an appropriate Si concentration prevents pore coarsening around the bonding interface. The bonding strength became low when the Si concentration in the Al–Si brazing precursor was excessively low.
