S. A. Istomin

Pseudocavitation during low-frequency treatment of melts

Low-frequency and ultrasonic treatments of a melt are compared theoretically. The phenomenon caused by low-frequency treatment of a melt and called pseudocavitation is considered. The conditions of the appearance of this phenomenon are revealed, and an experiment on mixing of a “light” aluminum powder with “heavy” Wood’s alloy is performed under pseudocavitation conditions.

Construction of viscosity diagrams for CaO–SiO 2 –Al 2 O 3 –8% MgO–4% B 2 O 3 slags by the simplex lattice method

The simplex lattice method of planning experiments is used to study the viscosities of CaO–SiO2–Al2O3–8% MgO–4% B2O3 slags in a wide chemical composition range. For each viscosity, we developed an adequate mathematical model in the form of a reduced third-order polynomial. The results of mathematical simulation are presented in composition–viscosity diagrams. Composition regions with a high fluidity of slags, the viscosities of which are 0.8–1.2 Pa s in the temperature range 1500–1600°C, are indicated in the diagrams.

High-temperature heat capacity of Y2Cu2O5

The temperature dependence of the molar heat capacity of Y2Cu2O5 has been measured at 328–953 K. The thermodynamic functions of the oxide compound have been calculated from the experimental data.

Influence of the mechanical activation of REE oxides on the electrical conductivity of borate melts

The influence of the mechanical activation of oxides M2O3 (La2O3, Ce2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Yb2O3, and Lu2O3) on electrical conductivity (æ) of the B2O3-M2O3 molten systems is investigated. It is assumed that the majority carriers in these melts can be protons which enter the melts due to the hydration of B2O3. The variation in the magnitude of for various M2O3 contents is explained by the corresponding variation in the structure of structural units as a result of the dissociation of the boron-oxygen groups, which include the OH groups. The activation energy of electrical conductivity in the B2O3-M2O3 melts increases due to the decay of superstructural units [B3O4.5] and B3O3O3/2OH as the temperature increases. The dependence of is found. In the B2O3-La2O3 → B2O3-Lu2O3 melts series, this energy follows the intraseries periodicity, which depends on the stabilization energy of fundamental terms of the ions of rare-earth elements (REE).

Heat capacity of Tb2Cu2O5 in the temperature range 379–924 K

The heat capacity of Tb2Cu2O5 in the temperature range 379–924 K has been measured using differential scanning calorimetry. It has been shown that the obtained dependence Cp = f(T) can be described by a combination of the Debye and Einstein functions.

High-temperature heat capacity of Gd2CuO4

The heat capacity of Gd2CuO4 has been studied by differential scanning calorimetry in the temperature range 362–958 K. It has been found that the temperature dependence of the molar heat capacity has an extremum near 590 K; the extremum is related to a phase transition from the high-temperature tetragonal phase to the low-temperature orthorhombic phase.

Effect of zirconium and molybdenum oxides on the viscosity and the electrical conductivity of oxide-fluoride slags

The effect of additions of zirconium and molybdenum oxides on the viscosity and the electrical conductivity of oxide-fluoride slags is studied using a vibration viscometry and an ac bridge.

Effect of mechanical activation of rare-earth metal oxides on the viscosity of borate melts

Effect of mechanical activation of yttrium-group rare-earth metal (REM) oxides on the viscosity of borate melts is studied. The concentration of Gd, Dy, Ho, and Lu oxides is found to affect the viscosity and solidification temperature of these melts.

Effect of titanium and molybdenum oxides on viscosity and electrical conductivity of oxide-fluoride slags

The effect of additives of titanium and molybdenum oxides on the viscosity and electrical conductivity of the Al2O3-CaO-CaF2 oxide-fluoride slag melts at 1750–1950 K is investigated by vibration viscosimetry and the ac bridge method. Crystallization intervals are established depending on the variation in the TiO2 and MoO3 concentrations in the melts from 0 to 25%, and it is revealed that the majority charge carriers are calcium and fluorine ions. These data indicate the complex-forming character of the behavior of Ti and Mo in aluminum-calcium oxide-fluoride melts.

Viscosity and conductivity of melts of the GeO2-PbO system

The temperature dependence of the viscosity and conductivity of melts of the GeO2-PbO system containing 25, 40, 50, 62.5, 66.8, and 75 mol % PbO is measured. The results are attributed to the structure of the studied melts. It is shown that current-carrying ions also determine the viscous flow.