The aim of this research was to study the interaction and solderability of Al₂O₃ ceramics and Ni-SiC composite by use of an active solder type Bi11Ag1.5Ti1Mg. The chemical composition of the solder is 86.5 wt% Bi, 11 wt% Ag, 1.5 wt% Ti, 1 wt% Mg. Soldering was performed by ultrasonic activation. This solder has a wide melting interval with the initial melting temperature of 263 ℃, what corresponds to the eutectic reaction. The liquidus temperature of this solder was determined at 437 ℃. The bond between the ceramic and the solder is formed by the interaction of the active metals Bi, Ag and Mg with the surface of the substrate Al₂O₃. The thickness of the Mg reaction layer at the interface was approximately 0.8 μm. The bond at the interface between Ni-SiC and solder was formed due to the interaction of the active metals Bi, Ag, Mg and Ti. Feasibility of Bi11Ag1.5Ti1Mg solder was assessed on the basis of analyses of joint boundaries and joint shear strength measurements. The average shear strength of Al₂O₃/Bi11Ag1.5Ti1Mg/Ni-SiC joint was 54 MPa.

The aim of this study was to characterize a Sn-Ti solder alloy containing 6 wt.% SiC nanoparticles and evaluate its use for direct soldering of SiC ceramics to a copper (Cu) substrate. Soldering was performed with direct ultrasound activation. The average tensile strength of the solder alloy was 17.1 MPa. Differential Thermal Analysis (DTA) analysis revealed an apparent transition at 234 ℃, corresponding to a eutectic reaction within the Sn-Ti binary system, indicating structural changes in the solder. The solder matrix consisted primarily of pure tin, while titanium combined with SiC nanoparticles to form a TiC phase. The existence of this phase was confirmed by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis of the solder. The bond at the interface between the SiC ceramic substrate and the solder was formed through diffusion and chemical reactions. The XRD analysis of the fractured surface from the SiC side confirmed the formation of phases such as TiC, Ti₂Sn, CTi₂, CuSn, SiC, and Cu₆Sn₅; the TiC and CTi₂ phases resulted from the interaction of active Ti in the solder with the SiC ceramic surface. The bond at the Cu substrate interface formed due to the high solubility of tin in the solder and the formation of probable CuSnTi and CuSnTi3₅ phases, along with a mixture of Sn + η Cu₆Sn₅ solid solution. The average shear strength of the SiC/Cu joint, fabricated using SnTi3 solder with 6 wt.% SiC nanoparticles, was 21.5 MPa.