Brazing of Copper Foam Using Cu-4.0Sn-9.9Ni-7.8P Filler Foil: Effect of Brazing Temperature and Copper Foam Pore Density

Copper (Cu) foam is a promising material that owns a high surface area that can be utilized in a thermal application. In this research, the brazing of Cu substrate to Cu foam in the sandwich configuration using Cu alloy filler foil was carried out. The foam at different pore per inch (PPI) of 15, 25 and 50 are brazed at different brazing temperatures. Mechanical and microstructure analysis were conducted to investigate a suitable brazing temperature and the best pore density of foam. The compressive strength of brazed 50 PPI foam has yielded the highest due to the highly dense interconnected branches. While the highest shear strength of brazed interface using 15 PPI foam has been recorded. The large branch size of 15 PPI foam has contributed to the sound joint between the brazed joint interface of Cu substrate and foam. Both mechanicals analysis above exhibits a highest strength at 660 °C as a brazing temperature The shear stress-strain curve of Cu substrate and foam brazed joint interface shows a brittle behaviour which accordance with the discoverable brittle phases of Cu3P and Ni3P using X-ray diffraction (XRD). Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) have presented the formation of Cu3P and Ni3P at the brazed joint interface of Cu substrate and foam.