The corrosion electrochemical behavior of copper-based alloys (L63, cupronickel, Monel, Cu–Al) in high-temperature salt electrolytes of various compositions in the galvanostatic mode is studied. Brass L63 is the most promising copper-based alloy for the production of nanoporous and mesoporous materials in salt melts. L63 brass samples have the smallest average pore diameter in experiments with a chloride melt. The pore size was 1.1 μm in the galvanostatic mode under the specified conditions (200 A/m2, 500°C). The results of cyclic voltammetry can be applied to predict the character of electrochemical destruction and to analyze the stages of conjugated anodic processes. The influence of the nature of the second alloy component on the character of electrochemical destruction and the formation of the developed surface layer of the alloys is found.

The electrical conductivity was measured from the melting point to 1280 K for molten 0.7 LiF-0.3 KBr (its composition corresponds to the top of the miscibility gap) containing (2.3, 4.4, 6.5, 8.8, and 11.2) mol % KCl or (1.2, 2.5, 5.5, and 10.2) mol % CsCl to establish the influence of this solute on the stability of the two-phase system. These results indicate that the temperature dependences of the conductivity along the saturation lines for all of the mixtures studied herein are similar to one another. Hence, this demonstrates that small additions of KCl and CsCl to the dissolving melt of LiF-KBr do not exert a substantial influence on its type of criticality. In the vicinity of the critical point, the temperature dependence on conductivity differences for melts is investigated and is described by the equation Delta kappa approximate to (T-c - T)(k), where k is the critical exponent (k = 0.98). The critical temperature changes as a function of the mixture composition and depends on the ion size of the salt added. The critical temperature increases continuously with the addition of CsCl to molten LiF-KBr, whereas it decreases as the fraction as KCl is added. This circumstance must occur during the organization process, as salts accumulate in the dissolving molten mixture, and they prevent the confluence of the phases at a given operating temperature. To interpret the experimental results, the charged hard sphere model for ionic melts in the Debye-Hiickel approximation was used with an account of the excluded volume.

The liquid+liquid phase equilibrium of molten mixtures of lithium fluoride with potassium and rubidium halides was investigated over an extended temperature range in the two-phase region along the saturation line by the electrical conductivity method. In the overwhelming majority of mixtures, the electrical conductivity for coexisting equilibrium phases increased when the temperature increased. For mixtures with only potassium bromide, it decreased because of the extensive solubility of potassium bromide in lithium fluoride. The electrical conductivity for the light phase was half the value of the conductivity of the pure lithium fluoride. The electrical conductivity of the heavy phase did not differ enough from the conductivity of the pure heavy alkali halides. At the same time, the solubility of the heavy component in LiF was many times less than the lithium fluoride solubility in the lower phase. This contradiction points to essential reorganisation of the structure of the light phase. The difference between the conductivities of the coexisting phases at equal temperatures increased as the radius of the halide anion or alkali cation grew. The temperature growth led to the increase in the conductivity difference along the saturation line for mixtures of LiF with RbI. For mixtures of LiF with lighter alkali halides, it decreased up to zero at the critical mixing point for LiF+KBr mixtures as the temperature increased. Between the coexisting equilibrium phases, a transient layer was revealed, where a conductivity gradient exists. The thickness of this layer decreased as the temperature decreased and the sum of the ionic radii of the mixtures increased.

The electrical conductivity κ of miscibility gap ionic melts of lithium fluoride with potassium, rubidium, and cesium bromides is measured. The role of the size and temperature factors in migration is discussed for the systems with a predominant Coulomb interaction of particles in the saturation line.

Conductivity of fused mixtures of lithium fluoride with cesium halides is measured in the stratification region. The difference of conductivities of coexisting equilibrium phases is shown to increase with the increase in the halide anion radius at equal temperatures and to decrease with the increase in the temperature.

The free energy of the surface of solid gold in binary molten mixtures of strontium and cesium chlorides is determined as a function of the temperature, salt-phase composition, and electric potential on the basis of changes in the weight of a freely hung electrode semi-immersed in electrolyte. Variations in the shape of the electrocapillary curve; the potential dependence of the electric charge density; and the concentration dependences of the potential of zero charge, surface energy and contact angle are utilized for elucidating the nature of interaction of the ionic-melt components between themselves and the gold electrode surface and the nature of adsorption of the salt-phase ions at the interface.

The interfacial free energy and contact angles intrinsic to the boundary between solid gold and molten chlorides of alkaline-earth metals and magnesium are determined by measuring the forces due to capillary rise. It is shown that, in a wide potential range, electrocapillary curves for BaCl2, SrCl2, and CaCl2 exhibit a maximum associated with the potential of zero charge (PZC). At potentials more anodic than PZC, a region is discovered in molten magnesium chloride, where the interfacial energy is virtually potential-independent, which is ascribed to partial charge transfer from the anions onto the metal. The angles of contact diminish in the series from BaCl2 to MgCl2.

The change of the interfacial free energy at the interfaces between nickel-aluminium and nickel-chromium alloys of various composition and eutectic Li2CO3-K2CO3 melts was studied as a function of potential. Experiments were performed in oxidizing, reducing, and inert atmospheres at 910 - 940 K; the method of meniscus weight was used. It was found that the contact angle decreases from 88 degrees to 0 degrees when one passes from a reducing atmosphere to a neutral and then to an oxidizing one. A region of potentials characterized by the partial charge transfer from the adsorbed oxygen anions to an electrode was discovered. This charge transfer results in the formation of complex anions and in the reversal of the surface charge of alloys. The pattern of the change in the values of the contact angles and potentials at the point of zero charge with the composition of alloys is revealed; this pattern shows that the content of chromium and aluminium in the surface layer exceeds that in the bulk of the alloys. The results are discussed from the viewpoint of the interaction between the components of the alloy and the oxygen ions.