Study of a mechanism of hard gold electrodeposition

Electrodeposition of nickel hardened gold was studied from a proprietary bath (Renovel N). Linear sweep voltammetry (LSV), chronoamperometry and chronopotentiometry were employed and Tafel curves determined. LSV studies revealed formation of a current peak connected with the inhibition of the deposition reaction. In the hard gold bath Tafel curves are characterized by two slopes: –0.47 V dec.^–1 between –0.5 and –0.8 V and –0.19 V dec.^–1 at more negative potentials; in the soft gold bath (without Ni) these slopes are: –0.35 V dec.^–1 and –0.15 V dec.^–1, respectively. Current efficiency of hard gold plating in galvanostatic conditions was on the average 54–57%, depending more on current density than on the charge passed (thickness of the deposit). No influence of oxygen on the process was found. It was also found, that the bath must be activated before reproducible results are obtained.     

Electrodeposition of nickel-cobalt-zinc alloys from a borate bath

The electrodeposition has been studied of nickel-cobalt-zinc alloys from a borate bath containing nickel sulphate (120–140 g dm^–3), cobalt sulphate (30–46 g dm^–3), zinc sulphate (144–168 g dm^–3), boric acid (30 g dm^–3) and ammonium chloride (2 g dm^–3). The operating conditions were: current density, 2.0–5.0 A dm^–2; temperature, 30–40°C and pH, 2.4 to 5.4. Light grey, semibright, stressed films have been obtained. However, the deposits consist partially of black powder when the concentration of the various components is increased. The brightness is found to increase with decreasing temperature and pH of the solution. The total cathode efficiency increases when the pH and temperature of the solution decrease, whereas at any particular pH and temperature it first decreases, reaches a minimum and then increases with increasing current density.     

Industrial tests of a process for biochemical clean-up of wastewater having a large surfactant content

Conclusions At an original SAS concentration of about 200 mg/liter, the efficiency of biochemical clean-up from SAS may reach 80–94% at a thiosulfate ion content of about 100 mg/liter, an active sludge dose of 2–3.2 g/liter, and an aeration time of 7–7.5 h (without allowing for the time for sludge regeneration).The optimum pH in the aeration tanks is in the range 6.8–7.5.Increasing the thiosulfate ion content of the wastewater or the duration of discharge of an elevated amount of thiosulfate ion leads to a reduction in the degree of clean-up of wastewater from SAS.Translated from Khimicheskie Volokna, No. 6, pp. 13–14, November–December, 1988.     

Deposition of a thin film of carbon nanotubes onto a glassy carbon electrode by electropolymerization

A novel and easy route for the deposition of a thin film of carbon nanotubes onto an electrode surface by electropolymerization is described. Multi-wall carbon nanotubes (MWNTs) were “dissolved” in aqueous alizarin red S (ARS, 3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonic acid, sodium salt) solution, and a very stable and well-distributed aqueous MWNTs–ARS solution was obtained. A thin film of MWNTs–ARS was successfully deposited onto the electrode surface by an in situ electropolymerization in aqueous MWNTs–ARS solution. The MWNTs–ARS thin film was characterized by scanning electron microscopy, Raman spectroscopy, UV–Vis spectroscopy and electrochemical techniques.     

Detonation of Secondary Explosives in a Vacuum Suspension

The existence of self–sustaining detonation in an evacuated suspension of the particles of a secondary explosive is shown experimentally. The experiments with HMX were performed in a vertical shock tube of diameter 0.07 m and length 7 m in the range of volume–average particle concentrations 0.32—0.9 kg/m³. It is shown that the vacuum–detonation velocity does not almost depend on the volume–average concentration of particles and it is (1750±50) m/sec and that the pressure profile of a vacuum–detonation wave is smooth. The data on the electric conductivity of vacuum–detonation products and the length of the reaction zone are given.     

Explosion of a cylindrical charge above a rigid surface

We investigated the explosion of a cylindrical charge, which lies on a rigid surface or is positioned at some height above it. The explosion is modeled by the jump between the background and the region occupied by gas at a high pressure, density, and temperature. In an analogous formulation, the explosion from the Tunguska meteorite impact [1–4] was modeled by spherical and cylindrical explosive waves which consider the gravitational back pressure. Explosions from charges with nontraditional shapes have been studied [5–8]. Reflections of an explosive wave from a point charge from a rigid surface have been examined [9–10]. A more complete review of investigations on the spatial effects of forming propagating explosive waves can be found in [11].Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 6, pp. 131–134, November–December, 1991     

Elastic behaviour of a model two-phase material

Dense Al₂O₃–NiAl composites containing 0–100% NiAl were prepared in the present study, and their elastic properties are determined by a dynamic method. Comparisons are made between the experimental data and several theoretical models. The elastic and shear moduli fall within the Voigt–Reuss bounds and close to the lower bound of the Hashin–Shtrikman (H–S) model. Nevertheless, the bulk modulus and Poisson’s ratio of the composites show strong dependence on their microstructural characteristics. As two phases are interconnected in the composites to form an interpenetrating microstructure, the bulk modulus deviates considerably from the Voigt–Reuss and H–S bounds. However, the Poisson’s ratio of the composites containing only one continuous phase differs from the model predictions.     

Special features of synthesis of a heat-resistant glass-ceramic coating

In order to protect Ni–Cr alloys from high-temperature corrosion, a new heat-resistant glass-ceramic coating was developed with a glass matrix synthesized on the basis of a composite R _x O–Al₂O₃–SiO₂–TiO₂ (R–Li^–, Na⁺, K⁺, Mg²⁺, Ca²⁺, Ba²⁺) system. The special features of the formation of crystalline phases in the glasses in heat treatment and the optimum regime for the formation of a glass ceramic structure are described.Translated from Steklo i Keramika, No. 3, pp. 30–32, March, 1996.     

Electrodeposition of Ni, Fe and Ni–Fe alloys on a 316 stainless steel surface in a fluorborate bath

Electrodeposition processes of Ni, Fe and Ni–Fe alloys on 316 stainless steel surfaces in fluorborate baths were studied using conventional electrochemical techniques and atomic force microscopy. The results showed that these processes occurred under mass transfer control, associated with nucleation and growth process. Cathodic current–time transients indicated that the nucleation and growth of Ni–Fe alloy was different from that of the single metal (Ni or Fe). For one, two nucleation and growth processes occurred during Ni–Fe alloy codeposition. Also, there was a nucleation and growth process of Ni–Fe alloy on Ni–Fe clusters, due to a change of the Ni–Fe alloy composition and phase. Homogeneous Ni–Fe alloy deposits could be obtained by pulse potential plating. AFM images of Ni, Fe and Ni–Fe deposits prepared by pulse potential plating revealed the following results: (1) the growth rate of Ni nuclei was faster in parallel than in perpendicular to the 316 electrode surface; (2) for Fe nuclei, the preferential growth direction was perpendicular to the 316 electrode surface; and (3) for Ni–Fe nuclei, there was no preferential growth direction and uniformly hemispherical Ni–Fe clusters were obtained.     

Interaction of a shock wave with a cloud of particles

The present paper is devoted to experimental and theoretical investigation of shock-wave propagation in a mixture of a gas and solid particles with clearly defined boundaries of the two-phase region (cloud of particles). The effect of qualitative transformation of supersonic flow behind a shock wave in a cloud of particles is shown experimentally and substantiated theoretically for volume concentrations of the dispersed phase of 0.1–3%.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 2, pp. 86–99, March–April, 1996.     

Three–Dimensional Simulation of Shaped Charges with a Star–Shaped Liner

Results of the three–dimensional simulation of the formation of a shaped–charge jet and the piercing of a steel target by a charge with a star–shaped liner are reported. The calculation results show the efficiency of the three–dimensional numerical technique TRÉK–UP used and the possibility of its applications to direct simulation of the problem considered. In addition, it is shown that one can optimize star–shaped charges significantly with a view to reaching higher efficiency.     

Thermodynamic Simulation of the Behavior of a Carbonized Refractory

Using a Gibbs energy minimization method, a computer-assisted thermodynamic simulation of the MgO – C – H2O – air system at 298 – 2400 K is carried out to gain an insight into the behavior of a carbonized periclase material under operating conditions. The effect of temperature and the ambient gas medium on phase and chemical transformations in the bulk and pore space of the composite is studied.     

Impregnation of a periclase-chromite lining with nickel matte

Results of an investigation of periclase-chromite linings in contact with matte (sulfide-metallic melt) in shaft melting of oxidized nickel ores are presented. It is shown that the sulfide components of matte, preferentially iron sulfide, impregnate the refractory, whereas the metal (21.9–23.1% Ni, 1.38–1.45% Co, 73.3–76.1% Fe, and 0.8–1.0% S) remains in the gaps between bricks. Chemical analysis data show that the sulfide-impregnated refractory contains 5.1–9.5% S, 9.8–27.9% Fe, 1.8–7.5% Ni, 0.09–0.15% Co, which markedly decreases the heat engineering parameters of the refractory and the entire lining. The results clarify the mechanism of failure of refractories and the formation of skull.Translated from Ogneupory, No. 6, pp. 28–29, June, 1995.     

Identification of a Sex Pheromone Component of the Raspberry Budmoth, Heterocrossa rubophaga

The female-produced sex pheromone of the New Zealand raspberry budmoth, Heterocrossa rubophaga, was investigated. Gas chromatographic–mass spectrometric analyses revealed the ketone, (Z)-12–nonadecen9–one (Z12–19–9–one). This compound had previously been found in extracts of the sex pheromone gland of the only other carposine moth for which a sex pheromone has been identified, Carposina niponensis, although its effect on the behavior of C. niponensis males had not been established. Field trapping trials in berry fruit gardens showed this compound to elicit high catches of male H. rubophaga, with the catch appearing to plateau (and perhaps decrease) above a dosage of 300 g on a red rubber septum. In an analysis of an extract of female H. rubophaga sex pheromone glands, there was a suggestion that the homologous (Z)-7–eicosen-11–one, the known sex pheromone component of C. niponensis, was also present. However this could not be established unequivocally and, in a field trial, addition of a small amount of this compound to Z12–19–9–one resulted in no significant increase in trap catch relative to traps baited with Z12–19–9–one alone.     

Computerized Solution of the Dynamic Sorption Process for a Ternary System in a Heterophase Medium

A mathematical model equation for the ternary adsorption–reaction process was developed and illustrated for the catalytic dehydrogenation of cyclohexane to benzene with the adsorption of hydrogen atoms as a monomolecular species on platinum–rhenium/alumina catalyst in inert and active carrier gases using pulse and continuous flow techniques. An optimization routine of the Nelder–Mead simplex method was used to estimate the surface reaction rate constant and adsorption equilibrium constant at different temperatures. These constants were then used to determine activation energies and adsorption equilibrium energies for cyclohexane dehydrogenation in inert (argon, helium) and active (hydrogen) carrier gases using pulse and continuous flow techniques. Numerical solutions for the ternary adsorption–reaction scheme were compared with the binary adsorption–reaction case where hydrogen adsorption is ignored. The predicted results for the ternary adsorption–reaction revealed that hydrogen adsorption during cyclohexane dehydrogenation is significant.     

A device for the take-up of pneumatically tangled acetate yarns onto a spinning package

Conclusions Three variants of take-up and winding devices have been developed; these permit one to take up yarn from the spinning machine onto a commercial package by a frictionless method and ensure a constant linear velocity of yarn winding.The device operates under the following regimes: linear winding rate, 400–600 m/min; yarn tension up to regulating roll, 4.5–5.0; tension after it, 8–9 cN; weight of package, 3 kg.The devices ensure obtaining acetate pneumatically tangled yarns with 15–35 pneumatically tangled sections per m of yarn with a uniform distribution over the yarn length; the density of the yarn in the package is 850–950 kg/m³.Translated from Khimicheskie Volokna, No. 1, pp. 46–48, January–February, 1985.     

Characterization of sepiolite as a support of silver catalyst in soot combustion

Turkish sepiolite–zirconium oxide mixtures were applied as a support for the silver catalyst in a soot combustion. Sepiolite–Zr–K–Ag–O catalyst was characterized by XRD, N₂ adsorption, SEM, TPR-H₂ and EGA-MS. The combustion of soot was studied with a thermobalance (TG-DTA). The modification resulted in a partial degradation of the sepiolite structure, however, the morphology was preserved. The adsorption of N₂ of the modified sepiolite is a characteristic for mesoporous materials with a wide distribution of pores. The specific surface area S_BET equals 83 m²/g and the pores volume is 0.23 cm³/g. The basic character of the surface centers of sepiolite is indicated by CO₂ desorption (TPD-MS) at 170 °C and at about 620 °C due to a surface carbonates decomposition. The thermodesorption of oxygen at 650–850 °C indicates the decomposition of AgO_x phases at the surface. The presence of AgO_x phases is also confirmed by TPR-H₂ spectrum (low temperature reduction peak at 130 and 180 °C). The high-temperature reduction at about 570 °C is probably related to Ag–O–M phases on the support.The soot combustion takes place at T₅₀ = 575 °C. Without silver (sepiolite–Zr–K–O) T₅₀ = 560 °C but sepiolite modified with silver (sepiolite–Zr–K–Ag–O) undergoes the same process at T₅₀ = 490 °C.     

Bag filters made of a modified carbonaceous material

Conclusions -- Results of investigation indicate that filter materials based on modified carbon fibres can be used to clean up gases having temperatures up to 350–400°C at a dust-particle size down to 4–6 µm.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 45–47, May–June, 1991.     

Model of the penetration of a metal barrier by a rod projectile with an angle of attack

A relatively simple dynamic model is proposed for calculating parameters characterizing the penetration of a barrier by a rod projectile with an angle of attack. Together with the factors examined in the case of axisymmetric penetration within the framework of the well-known Alekseevskii-Tate scheme, the model considers the action of transverse forces and rotation of the rod. Calculations of the penetration of steel barriers by tungsten projectiles with a relative length of 12.8–17.4 at collision velocities of 1800–2100 m/sec along a normal to the surface showed good agreement with experimental data for angles of attack from 0 to 68°.All-Union Scientific Research Institute of Experimental Physics, 607200 Aramas-16. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 3, pp. 104–109, May–June, 1995.     

Thermodynamic Simulation of the Behavior of a Carbonized Periclase Refractory with an Aluminum-Based Antioxidant

Using the method of Gibbs energy minimization, a computer-aided thermodynamic simulation of phase and chemical transformations in the MgO – C – Al – H₂O – air system at 298 – 2400 K is carried out to describe the behavior of a carbonized periclase material with an Al-based antioxidizing additive. The effect of temperature and environmental atmosphere on phase and chemical transformations in the material bulk and material's pore space is studied. The properties of a carbon matrix doped with aluminum are discussed.