Temperature influence on the equilibrium and kinetics of fluoride-ion adsorption by heat-treated Al oxyhydrates

The effect of temperature on the fluoride adsorption by heat-treated samples of aluminum alloy AMG-6 electrochemical machining products has been studied. Kinetic curves and adsorption isotherms at solution temperatures of 20, 30, and 40°C have been received, and the adsorption rate constants, diffusion coefficients, and the values of the activation energy have been determined. The obtained E _a value corresponds to values of the activation energy characteristic of ion exchange processes controlled by internal diffusion. Thermodynamic functions of the adsorption process ΔF₀, ΔH₀, and ΔS₀ have been calculated. The differential free molar energy changes, the isosteric heat, and the entropy of the fluorine adsorption have been analyzed versus the filling degree of the sample surface with fluorine ions. The absence of the process rate dependence on the mixing rates, as well as the character of the dependences of F (equilibrium degree reaching, %) on the √tdemonstrates that the process under consideration is controlled by an internal diffusion step. The mechanism of fluorine ion fixation on the modified surface of aluminum oxyhydrates has been discussed.     

Changes in mechanical properties in metal-forming processes

This article presents a paradigm for the mechanical properties of a metal that result from the plastic deformation that occurs in forming processes, including multiple-step or cyclic processes. Some of the new concepts included are a new strength designation that includes the sense (tensile or compressive), the direction (longitudinal, transverse, etc.), the specific type of deformation (tensile, compressive, etc.); a concept of an equivalent strain; and the apparent rules of strain strengthening. Examples of strength     

Mass transfer during extraction of sulfur from a layer of sulfur ore

A rather simple method has been developed for determining the process time of almost complete (98%) sulfur extraction from a layer of sulfur ore, as a function of the ore properties and of the layer length.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 21, No. 3, pp. 447–451, September, 1971.     

Numerical modeling of microplasma instability

The basic features of current flow in the form of microplasma pulses have been confirmed by numerical modeling. It is shown that a microplasma can appear spontaneously in the presence of a local inhomogeneity in the space-charge region of a p-n structure, and the increase in the temperature of the structure as a result of Joule heating leads to microplasma suppression. The kinetics, shape, and duration of the microplasma pulses were studied numerically as a function of the applied voltage and the parameters of the semiconductor structure. Fiz. Tekh. Poluprovodn. 31, 250–254 (February 1997)     

On Observation of Surface Electromagnetic Waves in Enclosed Spaces

An experiment on the study of waveguide propagation of surface electromagnetic waves with a frequency of 1 GHz in an enclosed space on free curved metal–dielectric interface was conducted. The distribution of the field of the electromagnetic wave along the propagation path was obtained for two cases: when a metallized tape was placed between radiating and receiving antennas and without the tape. It has been found that the field strength in the presence of the metallized tape is higher than the field strength without the tape.