Eutectic Bonding of Al pipe to Cu pipe

The bonding a copper pipe to an aluminum one was carried out by using eutectic reaction occurred at the faying interface when the copper pipe was inserted into the aluminum one. In order to understand the appropriate bonding conditions, the fracture and removing behavior of the oxide films on the pipe surfaces were investigated in detail. The following results were obtained. The strength and the bonded area of the joint are increased with increasing inserting rate and decreasing bonding temperature. Scraping the copper pipe edge by the solid-state edge of the aluminum one promotes the fracture and removing of the oxide film on the copper pipe surface and leads to the increase of bonding area and strength. At first the oxide film on the copper surface is consisted of copper oxide, however, the retained oxide film in the bonded layer is changed to oxide consisting of about 70% or more aluminum oxide. By making the oxide film on the copper surface thicken before inserting, that is more easily removed and less remained in the bonded layer.