Development and characterisation of a Y2Ti2O7-based glass-ceramic as a potential oxidation protective coating for titanium suboxide (TiOx)

A silica-based glass-ceramic, with Y₂Ti₂O₇ as the major crystalline phase, is designed, characterised and tested as an oxidation-protective coating for a titanium suboxide (TiO_x) thermoelectric material at temperatures of up to 600 °C. The optimised sinter-crystallisation treatment temperatures are found to be 1300 °C and 855 °C for a duration of 30 min, and this treatment leads to a glass-ceramic with cubic Y₂Ti₂O₇ and CaAl₂Si₂O₈ as crystalline phases. An increase of ~270 °C in the dilatometric softening temperature is observed after devitrification of the parent glass, thus further extending its working temperature range.Excellent adhesion of the glass-ceramic coating to the thermoelectric material is maintained after exposure to a temperature of 600 °C for 120 h under oxidising conditions, thus confirming the effectiveness of the T1 glass-ceramic in protecting the TiO_x material.     

New technological solutions to protect the lining of blast-furnace hearths

The use of schungite as a partial replacement for coke is practiced in Russia at a number of metallurgical plants, both in the production of foundry iron (its primary use) and in making conversion pig iron. The largest amount of coke is replaced when foundry iron is being made, the replacement coefficient in this case having a value within the range 0.8–1.3. Studies that included continuous monitoring of the temperature of the carbon blocks in blast furnaces with volumes of 1719, 3200, and 5580 m³ unambiguously demonstrate that the thickness of the slag crust in blast furnaces increases with the use of schungite. Protecting the lining of the hearth through the use of schungite is also accompanied by a decrease in coke consumption. __________ Translated from Metallurg, No. 8, pp. 53–57, August, 2007.     

Field evaporation of carbidized tungsten

The field evaporation of carbidized tungsten (ribbed crystals) was studied by the atom probe method at various temperatures of the sample in the regions of cryogenic, room, and elevated (1300–1600 K) temperatures. For a high pulsed (not less than 40%) component in the evaporating field, the room-temperature field evaporation mass spectra correctly reflect the surface composition of the evaporated sample. The mass spectra reveal a large number of molecular and polymerized (cluster) ions. Data from field ion desorption microscopy indicate that high-temperature field evaporation of a ribbed crystal proceeds via ion emission from walking and merging thermal-field microroughnesses.     

Dynamics of the magnetic field transport in a plasma opening switch

It is shown that the process of magnetic field penetration into the plasma bridge in a plasma opening switch is determined by the field diffusion near the magnetic piston, followed by the convective transport of magnetic field in the bridge. This transport is due to the field being “frozen in” to the flow of plasma behind the front of a shock wave, which is formed in the plasma accelerated by the magnetic field pressure.     

Mathematical simulation of the viscous properties of concentrated suspensions

A mathematical model for calculating the viscous properties of concentrated suspensions characterized by particle sizes of 30 to 800 µm), solids volume fractions of 1 to 70 vol %, different particle-size distributions, and a shear-rate range of 0.16 to 437 s^?1, which can describe the time evolution of the properties, is proposed. The model can be applied to calculating the viscous properties of catalyst oxide pastes, particulate-filled polymeric pastes, and the like.     

Use of liquid metals in nuclear and thermonuclear engineering,and in other innovative technologies

By now, a good deal of experience has been gained with using liquid metals as coolants in nuclear power installations; extensive knowledge has been gained about the physical, thermophysical, and physicochemical properties of these coolants; and the scientific principles and a set of methods and means for handling liquid metals as coolants for nuclear power installations have been elaborated. Prototype and commercialgrade sodium-cooled NPP power units have been developed, including the BOR-60, BN-350, and BN-600 power units (the Soviet Union); the Rapsodie, Phenix, and Superphenix power units (France), the EBR-II power unit (the United States); and the PFR power unit (the United Kingdom). In Russia, dedicated nuclear power installations have been constructed, including those with a lead-bismuth coolant for nuclear submarines and with sodium-potassium alloy for spacecraft (the Buk and Topol installations), which have no analogs around the world. Liquid metals (primarily lithium and its alloy with lead) hold promise for use in thermonuclear power engineering, where they can serve not only as a coolant, but also as tritium-producing medium. In this article, the physicochemical properties of liquid metal coolants, as well as practical experience gained from using them in nuclear and thermonuclear power engineering and in innovative technologies are considered, and the lines of further research works are formulated. New results obtained from investigations carried out on the Pb-Bi and Pb for the SVBR and BREST fast-neutron reactors (referred to henceforth as fast reactors) and for controlled accelerator systems are described.     

Microroughness evolution of the inner surface of copper pipes under drawing

The microroughness evolution of the inner surface of copper pipes under drawing is considered. The roughness parameter R _a is measured on the internal surface of pipes after pressing and drawing. It is revealed that R _a is minimal for hot-pressed pipes. Deformation by drawing to a logarithmic degree of deformation in 0.417 is accompanied by a rise in average parameter R _a from 0.20 to 6.16 μm, i.e., approximately 30 times. The highest growth rate of R _a is noted in the early pass of drawing. The increase in the dispersion of the value measured over drawing pass is also ascertained. The resulting phenomenon is explained by the effect of the copper grain turn.