Thermal conductivity of difluoromonochloromethane in the critical region

The thermal conductivity of difluoromonochloromethane (refrigerant R22) has been measured along six near-critical isotherms at reduced temperatures varying from =1.005 to =1.112 and at pressures ranging from 2.0 to 9.5 MPa. An anomalous enhancement of the thermal conductivity has been observed in the critical region. This anomalous behavior is consistent with theoretical predictions and equations for the thermal conductivity as a function of density and temperature are presented.     

Service of refractories in continuous casting of stainless steel

Conclusions Work was done on studying the service of refractories in continuous casting of stainless steel.It was established that refractories produced by domestic industry are suitable for this process and make it possible to obtain continuously cast billets in accordance with the requirements of TU 14-105-469-83. Gas protection of the stream of metal causes additional refining of the metal of nonmetallic inclusions and makes it possible to increase the quality of the cast billet.Stream treatment of the metal with inert gas makes it possible to significantly reduce encrustation of the nozzle channel with products of interaction of the molten metal with the refractory material of the ladle nozzle.Translated from Ogneupory, No. 6, pp. 52–55, June, 1985.     

Kinetics of the Change in the Surface Profile of Aluminum Bronzes during Cavitation Wear

Aluminum bronzes used in manufacturing ship propellers have been tested for cavitation wear using magnetostrictive vibrator in fresh water. The cavitation attack intensity was varied by changing the amplitude of horn end oscillations from 15 to 25 µm. It has been demonstrated that, within the incubation period of the cavitation wear, the arithmetic mean deviation R_a of the assessed profile, which is the parameter of roughness height, increases as linear function of the test duration. The R_a value that corresponds to the end of the incubation period is constant and does not depend on the cavitation attack intensity. The revealed characteristic properties allow the profile measurements to be used in predicting the duration of the incubation period for the cavitation wear of aluminum bronzes.     

Conformational and hydrodynamic parameters of hyperbranched pyridylphenylene polymers

Hydrodynamic and optical methods were applied to study conformational and physical properties of hyperbranched pyridylphenylene polymers in dilute solutions. The samples were synthesized using Diels–Alder polycyclocondensation. It was demonstrated that hydrodynamic properties of the studied macromolecules were typical for compact non‐percolated spheres. Optical and electro‐optical methods revealed information regarding the shape and asymmetry of the macromolecules (p ≈ 1.4). The contributions of optical shape effect to the observed flow birefringence of polypyridylphenylene solutions and intrinsic anisotropy of polarizability were evaluated and analysed. It was shown that varying the polymer composition (i.e. the degree of branching) caused considerable changes in the anisotropy of optical polarizability of the polymers. Dramatic difference of the electro‐optical properties in non‐polar (toluene) and polar (tetrachloroethane) solvents was found; this difference was related to the orientational correlation of polar solvent molecules with respect to the macromolecules. Dynamic properties were studied by non‐equilibrium electric birefringence which had a reasonable agreement with the dimensions estimated from hydrodynamic data. © 2016 Society of Chemical Industry     

Phase formation in gas-phase combustion and pyrolysis reactions under spark and radio-frequency discharge conditions

Doped ultrafine silicon dioxide powder with a narrow particle size distribution was obtained by RF discharge-stimulated dichlorosilane (SiH₂C) oxidation at a low pressure using isobutylene as the combustion inhibitor and chromium hexacarbonyl (Cr(CO)₆) as the dopant. The formation and morphology of the ultrafine particles are governed by the parameters of the RF discharge and by the chemical mechanism of the combustion reaction yielding the aerosol. Submicron-sized filamentous carbon structures can be obtained by isobutylene decomposition under spark discharge conditions in the presence of a molybdenum metal catalyst.     

Thermodynamics of sodium molybdate evaporation

High-temperature mass-spectrometry is used to study the evaporation of Na₂MoO_4(l) at 1050–1300 K. Na₂MoO_4(g) molecules are found to be present in the vapor. The partial pressure of Na₂MoO_4(g) is determined to be logp = 13794/_T + 6.19. The enthalpy of sublimation Δ _s H ₀^∘ (Na₂MoO_{4 (s)}) = 352 ± 20 kJ/mol is determined using the third law of thermodynamics. The atomization energy of the Na₂MoO_4(g) molecules is calculated to be Δ _at H ₀^∘ (Na₂MoO_4(g)) = 2960 ± 40 kJ/mol.     

Anisotropic ordered structures of silicon and silicon carbide by chemical vapor deposition

Anisotropic ordered structures of silicon and silicon carbide were prepared by chemical vapor deposition (CVD) technique using dichlorosilane (DCS), CCl₄, and CF₂Cl₅ and nitrogen gas as the components of starting gaseous mixtures. It has been shown that nitrogen molecules react at the active sites of substrate surface formed upon its etching with the 7.5% DCS + 7.5% CCl₄ + 85% N₂ gaseous mixture.     

Structure and properties of macromolecules with side dendrons based on <Emphasis Type="Italic">L</Emphasis>-aspartic acid

The molecular characteristics of cylindrical first-third generation dendrimers carrying dendrons based on L-aspartic acid are compared. It is shown that both the generation number of side dendrons and their structure determine the conformational, hydrodynamic, optical, and dipole characteristics of dendrite macromolecules. It is found that the studied class of cylindrical dendrimers is distinguished by a marked amount of intramolecular hydrogen bonds between side dendrite substituents. These bonds ensure the unusual combination of high kinetic rigidity and a compact conformation (low equilibrium rigidity) of macromolecules. The rupture of hydrogen bonds leads to an enlargement of molecular coils (an increase in equilibrium rigidity) that is accompanied by a sharp drop in kinetic rigidity.     

Characteristics of a Vortex Diode of Increased Diodicity

Russian Engineering Research - The characteristics of a vortex diode of increased diodicity are determined experimentally. The results are compared with those for a classic diode.