Microstructural Analysis of Porous Nickel Brazed to Copper and Stainless Steel using Different Brazing Filler Metals

The microstructures of brazing porous Nickel (Ni) to copper and stainless steel (Cu/Porous Ni/SS304) was investigated. A porous Ni with pore densities of 15 PPI (pores per inch) and filler with compositions of 72Ag-28Cu and 77.4Cu-9.3Sn-7P-6.3Ni (Ag: Silver; Cu: Copper; Sn: Tin; P: Phosphorus; Ni: Nickel) were employed. The brazing process was conducted at different brazing temperatures: 830˚C, 870˚C and 910˚C for 15 minutes brazing time with heating and cooling rate of 10˚C/min, respectively. The aim of this research is to analyse and compare the microstructure of using different types of filler metal in order for joint porous Ni to copper and stainless steel. According to the initial observations from an optical microscope (OM) after cross-section, the used of filler metal BAg-8 and VZ2250 acquired a bonding joining than the used of filler metal BAg-8 solely. Thus, Field Emission Scanning Electron Microscope (FESEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS) was used to characterise the bonding of microstructure of filler metal BAg-8 and VZ2250. Besides, the joint strength of Cu/Porous Ni/SS304 with filler metal BAg-8 and VZ2250 was evaluated with shear strength at different brazing parameters. Consequently, it can be concluded that used of filler metal BAg-8 and VZ2250 performed a better joint microstructure as compared to the used solely of filler metal BAg-8.