The paper discusses the scientific understanding of the role of interfacial phenomena in joining of dissimilar materials using liquid-phase-assisted processes. From the example of the Sn-alloy/Cu system, it is demonstrated that interaction in the liquid solder/substrate couples is accompanied by a number of complex interfacial reactions leading to significant changes in the structure and chemistry of interfaces (solder/substrate, solder/environment, substrate/environment) and remaining solder layer that finally influence the mechanical properties of solder joints. The experimental data on wetting behavior, interface characterization, and mechanical properties of different solder/metal substrate couples are analyzed in order to display the role of such factors as time and temperature of interaction, environment (protective atmosphere, flux), presence of oxide films on interfaces, alloying additions to a solder, formation of interfacial phases, and porosity.

The aluminothermic reduction process of manganese oxide from different slags by aluminum was investigated using pure Al and two types of industrial Al dross. Two types of MnO-containing slags were used: a synthetic highly pure CaO-MnO slag and an industrial high carbon ferromanganese slag. Mixtures of Al and slag with more Al than the stoichiometry were heated and interacted in an induction furnace up to 1873 K, yielding molten metal and slag products. The characterization of the produced metal and slag phases indicated that the complete reduction of MnO occurs via the aluminothermic process. Moreover, as the Al content in the charge was high, it also completely reduced SiO₂ in the industrial ferromanganese slag. A small mass transport of Ca and Mg into the metal phase was also observed, which was shown to be affected by the slag chemistry. The obtained results indicated that the valorization of both Al dross and FeMn slag in a single process for the production of Mn, Mn-Al, and Mn-Al-Si alloys is possible. Moreover, the energy balance for the process indicated that the energy consumption of the process to produce Mn-Al alloys via the proposed process is insignificant due to the highly exothermic reactions at high temperatures.

For a successful implementation of newly proposed silicon-based latent heat thermal energy storage systems, proper ceramic materials that could withstand a contact heating with molten silicon at temperatures much higher than its melting point need to be developed. In this regard, a non-wetting behavior and low reactivity are the main criteria determining the applicability of ceramic as a potential crucible material for long-term ultrahigh temperature contact with molten silicon. In this work, the wetting of hexagonal boron nitride (h-BN) by molten silicon was examined for the first time at temperatures up to 1750 °C. For this purpose, the sessile drop technique combined with contact heating procedure under static argon was used. The reactivity in Si/h-BN system under proposed conditions was evaluated by SEM/EDS examinations of the solidified couple. It was demonstrated that increase in temperature improves wetting, and consequently, non-wetting-to-wetting transition takes place at around 1650 °C. The contact angle of 90° ± 5° is maintained at temperatures up to 1750 °C. The results of structural characterization supported by a thermodynamic modeling indicate that the wetting behavior of the Si/h-BN couple during heating to and cooling from ultrahigh temperature of 1750 °C is mainly controlled by the substrate dissolution/reprecipitation mechanism.

The aluminum recovery from white aluminum dross by a mechanical treatment and sizing followed by remelting process was investigated. The dross was subjected to a ball mill, and the obtained particles were sized in different ranges. They were studied by advanced materials characterization techniques. It was found that the larger particles contain high metallic portions, and most non-metallic components of the dross are in the fine fraction < 1 mm. The Al-rich particles (> 1 mm) were remelted at 900°C to recover aluminum. It was found that the metal structure after remelting is homogeneous and consisted of a dominant metallic aluminum matrix, containing an average of > 96% Al with around 99% total metallic components. The results show that the applied method is a good economic alternative for the aluminum recovery from white dross, which is important for the valorization/recycling of industrial waste and circular economy.

The solderability of the SAC305 alloy in contact with printed circuit boards (PCB) having different surface finishes was examined using the wetting balance method. The study was performed at a temperature of 260 °C on three types of PCBs covered with (1) hot air solder leveling (HASL LF), (2) electroless nickel immersion gold (ENIG), and (3) organic surface protectant (OSP), organic finish, all on Cu substrates and two types of fluxes (EF2202 and RF800). The results showed that the PCB substrate surface finish has a strong effect on the value of both the wetting time t ₀ and the contact angle θ. The shortest wetting time was noted for the OSP finish (t ₀ = 0.6 s with EF2202 flux and t ₀ = 0.98 s with RF800 flux), while the ENIG finish showed the longest wetting time (t ₀ = 1.36 s with EF2202 flux and t ₀ = 1.55 s with RF800 flux). The θ values calculated from the wetting balance tests were as follows: the lowest θ of 45° was formed on HASL LF (EF2202 flux), the highest θ of 63° was noted on the OSP finish, while on the ENIG finish, it was 58° (EF2202 flux). After the solderability tests, the interface characterization of cross-sectional samples was performed by means of scanning electron microscopy coupled with energy dispersive spectroscopy.