Kompleksnoe Ispolzovanie Mineralnogo Syra = Complex use of mineral resources

Thermodynamics of Evaporation of Liquid Magnesium - Tin Alloys

V.N. Volodin — 2026-01-28

Based on the values of the partial pressures of magnesium above dimagnesium stannide and melts with tin, determined by the boiling point method (isobaric and isothermal variants, respectively) and tin, calculated by numerical integration of the Gibbs - Duhem equation in accordance with known expressions, the thermodynamic functions were determined: changes in entropy, enthalpy, and free energy of evaporation. Methods to determine the vapor pressure of isobaric and isothermal variants of the boiling point method and calculate thermodynamic values are described. The dependences of the values of partial vapor pressure of magnesium and tin were determined, based on which the energy functions were determined. The measurement error was 7.07%. Data on the change in evaporation entropies are presented graphically. An increase in the partial entropies of evaporation of magnesium and tin was noted with a decrease in their content in the alloy (each) to less than 20 at. %. Extremes are noted: a maximum for magnesium and a minimum for tin at a concentration corresponding to the stoichiometric composition of dimagnesium stannide (60 at. % Мg). The latter indicates the presence of a dissociating compound in the liquid phase that affects evaporation. The values of the change in enthalpy and Gibbs free energy of evaporation are tabulated. It was established that the values of partial and integral enthalpies and Gibbs free energy of vaporization monotonically increase from Mg to Sn in accordance with second-degree dependencies on the concentration of components in the alloy and linearly (Gibbs energy) with temperature. The very small change in the integral value of the free energy of evaporation of magnesium (0.03 ± 0.002 kJ/mol) at 1373 K (1100 °C) indicates a practical coincidence with the boiling point of magnesium. The energy functions of evaporation of magnesium-tin melts will supplement the thermodynamic database and can be used for thermal engineering calculations in the design of distillation processes and apparatus.

Deposition Methods of Multilayer Hard Coatings for Improving Tribological Performance: A Mini-Review

N. Bakhytuly — 2026-01-29

Multilayer hard coatings remain among the most effective engineering solutions for reducing friction and wear and for extending the service life of components operating under high contact loads. However, their practical performance is governed not by multilayering per se, but by the extent to which the selected deposition technology enables reproducible control over three key parameters: layer density and defectiveness, adhesion to the substrate and/or interlayers, and architectural tunability through interface quality. This mini-review systematizes deposition approaches relevant to tribological applications and proposes a generalized classification comprising chemical processes (sol–gel, chemical vapor deposition (CVD), atomic layer deposition (ALD), hydrothermal synthesis, electrodeposition, anodization, and electroless coatings), physical vacuum techniques of the PVD family (magnetron sputtering, cathodic arc deposition, hollow cathode discharge (HCD) ion plating, ion beam assisted deposition (IBAD), among others), as well as hybrid and functional solutions (PVD+CVD, composite, self-lubricating, and nanocomposite systems). It is demonstrated that the selection of a deposition process for multilayer architectures must be based on technological constraints that directly affect interface stability and coating durability, including the deposition temperature window and conformality, interfacial diffusion-induced boundary blurring, residual stresses, and critical defects such as porosity, macroparticles, and growth-related imperfections. Practical guidelines are formulated for correlating “architecture–deposition regime–microstructure–tribological behavior,” and key directions for future research are identified, including interface and defect engineering, targeted hybridization of deposition processes to compensate for intrinsic limitations (conformality, density, adhesion, and interface stability), and the use of predictive modeling validated by comparable tribological testing.