Analysis of zinc coatings on the basis of the iron-zinc phase diagram

The structure of zinc coatings is studied on the basis of the iron-zinc phase diagram, and the coating properties are compared. Corrosion tests indicate that diffusional zinc coatings are preferable in challenging operating conditions. Their structure consists mainly of intermetallides (iron-zinc phases) whose corrosion resistance is greater than that of pure zinc, primarily on account of passivation by zinc ferrites (ZnFeO₂, ZnFe₂O₄), as well as ZnO. The coating life in various aggressive media is considered, together with the main applications of zinc coatings.     

Road bitumen's based on the vacuum residue of heavy oil and natural asphaltite: Part I – chemical composition

This work is devoted to studying the possibility of producing bitumen for road construction by using vacuum residue >420°C of heavy oil of the Ashal'chinskoe field in and natural asphaltite Spiridonovskoe field from Permian deposits in Tatarstan. The effect of natural asphaltite as a solid disperse phase element on the structural and group composition of the residual heavy oil product and its malacometrical qualities (penetration, extensibility, softening point, resistance to aging and adhesion) is revealed. The production of samples of compounded bitumen production was carried out by introducing the required amount of the shredded asphaltite to deasphaltizat vacuum residue of heavy oil and heating their mixture to 220°С with vigorous stirring. Changes in the composition and physical and chemical properties of deasphalting the residual heavy oil product, associated with the amount of injected asphaltite, showed the possibility of production of modified bitumen with better adhesion properties that correspond to road bitumen.     

Tuning catalytic performances of cobalt catalysts for clean hydrogen generation via variation of the type of carbon support and catalyst post-treatment temperature

Multi-walled carbon nanotubes, three types of activated carbons, single wall carbon nanotube and reduced graphene oxides were used to synthesize nano-sized Co catalysts for H₂ preparation via NH₃ decomposition. Catalyst samples were characterized by number of techniques such as N₂ physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopes (XPS), Transmission electron microscopy (TEM), CO chemisorption, temperature-programmed reduction (H₂-TPR) and temperature-programmed desorption (N₂-TPD). The catalytic activities of the studied catalysts for H₂ production via NH₃ decomposition were measured in a fixed-bed micro-reactor. Co catalyst supported on multi-wall carbon nanotubes has shown the highest catalytic activity. The Co particles size was significantly affected by the variation of the post-treatment temperature. The Co particles size in the range of 4.7–64.8 nm can be effectively controlled by varying post-treatment temperature between 230 and 700 °C. The maximum TOF of NH₃ decomposition was registered on cobalt catalyst post-treated at 600 °C.     

MBE-grown nanoheterostructures with increased electron mobility

Multilayered nitride heterostructures AlN/AlGaN/GaN/AlGaN are grown using a Nanofab-100 multichamber domestic complex involving a STE3N3 specialized installation of molecular beam epitaxy. The obtained heterostructures have high structural quality, smooth morphology, and a low dislocation density, which demonstrates the high potential of the nanotechnological complex.     

Investigation of the influence of the initial state of powder,pore-forming additions,and U<Subscript>3</Subscript>O<Subscript>8</Subscript> on the microstructure and strength of fuel pellets

It is shown that the initial state of uranium dioxide powder has no effect on the density, microstructure, and strength of pellets. Pore-forming agents and U₃O₈ used in fabrication lower the pellet strength because their particles are not spherical. To increase pellet strength, it is recommended that U₃O₈ be subjected to special processing to spheroidize the particles before mixing for uranium dioxide powder.     

Results from tests of the P-67 boiler used as part of a 800-MW power unit

Results from the balance tests of a retrofitted P-67 boiler carried out in the period 2006–2008 are presented. The tests involved assessment of the change with time of the heating-surface thermal efficiency coefficients in running the power unit at its base loads in the range 740–800 MW, with seven to eight coarsegrinding mills switched into operation, with the open and closed gate values installed in the channels supplying air-powder mixture to the fourth-tier burners, and with the fraction of air supplied for lower blasting equal to 5–7% and that for the startup burners, 2%. The combined cleaning system operated in its design mode with additional blowing operations according to special control signals. The furnace waterwalls and the convective shaft surfaces were subjected to mechanical cleaning every year during current repairs.     

Express method of the quantitative determination of nitrites by computer colorimetry using new reagent compositions

The possibilities of using new reagent compositions based on diazo and azo dyestuff components that contain sulfonic groups are considered to determine nitrites in the presence of the contents of chlorides. New reagent compositions based on 1-hydroxynaphthalene-3,6-disulfonic acid in combination with 2,6- nitroorthanilic and 2,6-dichlorosulfanilic acids have been used to create indicator powders and indicator papers for the quantitative test determination of nitrite ions. Test methods based on sustainable indicator powders and indicator papers have been developed with the use of the ilPro portable spectrophotometer and PlustekSmartPhoto P60 compact mobile scanner combined with the Vuescan universal scan program. It has been shown that the sensitivity of the visual determination of nitrites in liquids using indicator papers is 0.5 mg/L. The sensitivity of the test method that uses indicator papers, the PlustekSmartPhoto P60 mobile scanner, and the ilPro portable spectrophotometer is 0.2 mg/L. Upon using the indicator powder and i1Pro portable spectrophotometer, the range of defined concentrations of nitrite ions is 0.01–5 mg/L.     

The stability of a balloon support subjected to blasting

Journal of Mining Science -     

Conditions for obtaining ultrafiltration membranes from a solution of polyacrylonitrile in dimethylformamide in the presence of formamide

The possibility to obtain ultrafiltration polyacrylonitrile terpolymer membranes in the presence of formamide in dimethylformamide polymer solution was studied. Correlation between the changes in viscosity and rheological characteristics of the polymer solutions, on the one hand, and the equivalent pore radii, efficiency, and selectivity of membranes, on the other hand, were found. The concentration of formamide was varied from 0 to 4 mass %. The dynamic characteristics of the membranes were determined with regard to calibrators having different molecular weight. © 1996 John Wiley & Sons, Inc.     

Prediction of Ferroalloy Properties for Expert Evaluation of the Efficiency of their Use During Addition to Steel in a Ladle Furnace Unit

Metallurgist - A procedure is developed for calculating criteria for estimation and evaluation of chemical and structural micro-inhomogeneity of ferroalloy production melts. Models are proposed for...