2022 年 61 巻 1 号 p. 235-239
Copper alloys with excellent machinability and thermal conductivity are widely used as piping materials, and brazing is used as the connection method. Ants’ nest corrosion is one of the causes of corrosion damage to copper pipes. Corrosion resistant copper alloys have been developed by adding a small amount of various elements to pure copper to suppress the occurrence of ant’s nest corrosion. However, there are many unclear points about the brazing properties of these corrosion resistant copper alloys.
In this study, brazing was performed using corrosion resistant copper alloys, and the microstructure of the cross section of the brazed part was observed using optical microscope and EPMA elemental analysis. The corrosion resistant copper alloys used were one copper alloy with Mn and the other a copper alloy with P. In addition, the area of the fillet was measured evaluated the brazing–ability.
As a result, it was confirmed that braze joints using BCuP–8 had better brazing–ability than those using BAg–7. It was also found that Mn in the pure copper matrix had a negative effect on brazing–ability. Furthermore, it was found that Mn added to the pure copper base metal had a strong influence on brazing–ability in the brazing material with Cu solid solution as the primary crystal. On the other hand, P contained in the pure copper base metal, P was detected at the interface between the brazing layer and the base metal. Therefore, good brazing–ability was obtained.
