Wettability Study of Soldered Joints in SiC Ceramics and Combined Ni-SiC Using SnSbTi-Based Solder and Electron Beam Heating

The reactive soldering of silicon-carbide (SiC) ceramics to a Ni-SiC composite was investigated using an Sn-5Sb-3Ti active solder and electron-beam heating at 750 °C, 850 °C and 950 °C. Wettability: The average contact angle decreased from 94 ± 4° (750 °C) to 60 ± 3° (850 °C) and further to 24 ± 2° (950 °C), demonstrating progressively improved spreading of the filler with increasing temperature. Interfacial reactions: Continuous layers of Ni₃(Sn,Sb)₄ and Ti₆(Sn,Sb)₅ formed along the Ni-SiC/filler interface, the latter confirming Ti diffusion that activates the wetting of the composite surface. Mechanical performance: Shear-lap tests on three joints per condition yielded 39 ± 6 MPa (750 °C), 27 ± 2 MPa (850 °C) and 36 ± 15 MPa (950 °C). The highest and lowest individual values at 950 °C were 51 MPa and 21 MPa, respectively. These results show that a higher soldering temperature lowers the contact angle and promotes interfacial reaction, but only a moderate improvement in average joint strength is obtained. These findings demonstrate a flux-free route to bond SiC ceramics with Ni-SiC composites, which is highly relevant for next-generation power-electronics modules and other high-temperature applications.