The aim of this research was to study the wettability and solderability of SiC ceramics by the use of an active solder of the type Sn5Sb3Ti in a vacuum by electron beam heating. This solder exerts a narrow melting interval, and only one thermal effect, a peritectic reaction, was observed. The liquidus temperature of the solder is approximately 243 °C. The solder consists of a tin matrix where the Ti₆(Sb,Sn)₅ and TiSbSn phases are precipitated. The solder wettability on a SiC substrate decreases with decreasing soldering temperature. The best wetting angle of 33° was obtained in a vacuum at the temperature of 950 °C. The bond between the SiC ceramics and the solder was formed due to the interaction of Ti and Ni with silicon contained in the SiC ceramics. The formation of new TiSi₂ and Ti₃Ni₅Si₆ phases, which form the reaction layer and thus ensure the bond formation, was observed. The bond with Ni is formed due to the solubility of Ni in the tin solder. Two phases, namely the Ni₃Sn₂ and Ni₃Sn phases, were identified in the transition zone of the Ni/Sn5Sb3Ti joint. The highest shear strength, around 40 MPa, was attained at the soldering temperature of 850 °C.

The aim of the research was to characterize the soldering alloy type Zn-Mg-Sr and direct the soldering of SiC ceramics with Cu-SiC-based composite. It was investigated whether the proposed composition of the soldering alloy was appropriate for soldering those materials at the defined conditions. For the determination of the solder melting point, TG/DTA analysis was applied. The Zn-Mg system is of the eutectic type with a reaction temperature of 364 °C. The effect of strontium on the phase transformation was minimal, owing to its lower content. The microstructure of the soldering alloy type Zn3Mg1.5Sr is formed of a very fine eutectic matrix containing segregated phases of strontium—SrZn₁₃ and magnesium—MgZn₂ and Mg₂Zn₁₁. The average tensile strength of the solder is 98.6 MPa. The tensile strength was partially increased by solder alloying with magnesium and strontium. The SiC/solder joint was formed due to the distribution of magnesium from the solder to the boundary with the ceramics at the formation of a phase. Owing to soldering in air, oxidation of the magnesium took place and the oxides formed were combined with the silicon oxides that remained on the surface of the ceramic material—SiC. Thus, a strong bond based on oxygen was obtained. An interaction between the liquid zinc solder and the copper matrix of the composite substrate took place at the formation of a new phase—γCu (Cu₅Zn₈). The shear strength was measured on several ceramic materials. The average shear strength of the combined SiC/Cu-SiC joint fabricated with Zn3Mg1.5Sr solder was 62 MPa. When soldering similar ceramic materials mutually, a shear strength of as much as around 100 MPa was observed.

The aim of this study was to characterize a Zn-Mg type soldering alloy and direct soldering of SiC ceramics with a copper substrate. The Zn1.5Mg solder exerts a wider melting interval. The temperature of the eutectic reaction was 365 °C, and the liquidus temperature was 405 °C. The microstructure of the soldering alloy is comprised of a zinc matrix. Segregation of binary eutectics in the form of (Zn) + Mg₂Zn₁₁ lamellas occurred on the boundaries of Zn grains. Additionally, the presence of a MgZn₂ magnesium phase was observed in the solder matrix. The SiC/solder bond was formed due to magnesium distribution from solder to the boundary with SiC ceramics, where magnesium reacts with silicon, which is infiltered in SiC ceramics. By a mutual interaction, a new Mg₂Si phase is formed. An interaction between the molten zinc solder and Cu substrate occurred on the boundary of the Cu/substrate joint at the formation of a transition zone composed of two new phases, namely the γCu (Cu₅Zn₈) non-wettable phase type, approximately 30 µm wide, and a wettable (CuZn₄) phase type ε, approximately 12 µm wide. The average shear strength of a combined SiC/Cu joint fabricated using Zn1.5Mg solder was 44 MPa.