Rebuilding of the reactor in a G-43-107M/1 cat cracker

The rebuilding of the reactor for a cat cracker with incorporation of a set of new process components and equipment subassemblies, which are directed toward a reduction in the portion of nonselective secondary reactions taking place in the separation and stripping sections of the reactor, is described; this has made it possible to improve the productivity and effectiveness of the cat cracker. Publicly owned joint-stock company VNII NP. OOO Avtotekhproekt. Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 10–11, March–April, 2009.     

Formation of silicon nanocrystals in SiN<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> film on PET substrates using femtosecond laser pulses

The formation of Si nanoclusters under the action of femtosecond laser pulses in a SiN _x film containing excess silicon has been studied. The initial film was grown by plasmachemical deposition at 100°C on a PET substrate. The pulsed crystallization was effected by a Ti-sapphire laser operating at a wavelength of 800 nm and a pulse duration of about 50 fs. According to the Raman spectroscopy data, the pulsed laser annealing stimulated the accumulation of excess silicon in nanoclusters and their crystallization. The proposed approach can be used for the formation of semiconductor nanocrystals in dielectric films on various plastic (polymer) substrates.     

Structure and properties of small clusters of transition 3<Emphasis Type="Italic">d</Emphasis>-element oxides

The results of calculations of the parameters of the equilibrium structures of small clusters of transition 3d-element oxides are presented. The calculations are performed by the spin-unrestricted Hartree-Fock method. The properties of the most stable structures, i.e., those with the lowest total energies among all those obtained, are discussed.     

Giant pulsar pulses for precision comparison of clocks

The possibility of achieving high-precison comparison of clocks with the use of giant pulsar pulses of enormous peak density of a nanosecond flux is considered. There are practically no constraints on the distance between the synchronized clocks, which may be located either on Earth or in outer space. Radio telescopes of moderate dimensions, low-noise receivers, and high-speed recorders are needed for a such a comparison of clocks. Giant pulsar pulses may be used for space navigation as well as for determining moments (epochs) in the scale of pulsar time.     

Dynamics of laser bullet propagation in carbon nanotube array with metal inhomogeneities

The problem of the propagation of a solitary wave—a two-dimensional analog of the so-called laser (light) bullet—in an array of carbon nanotubes with metal inhomogeneities (defects) has been considered. An effective equation for the vector potential of this wave is obtained and numerically studied. It is established that the scattering of a laser bullet on a pair of metal inhomogeneities is accompanied by characteristic “beats” of the electromagnetic field.     

Improving the controlled cooling of hot-rolled steel coils

The thermostatting of alloy-steel coils after hot rolling in a continuous broad-strip mill is considered. A technological chart of slow controlled cooling of the coils is developed. Measures are proposed for the production of high-quality and highly profitable steel coils without additional capital expenditures or operating costs.     

Experiments on Dynamic Behavior of Molten Metal and Solid Particles Under Direct Current Passing

At electrodischarge sintering of powder mixtures by electric direct current, some essential displacements of molten metal and solid particles were revealed. Such displacements at conventional sintering were not known to us. The objects were powders (mixtures): Sn–Cu (dispersivity 100–200 µm); Sn–high-temperature alloy on nickel base or electrocorundum; copper alloy-electrocorundum (dispersivity 63–500 µm); Ni (dispersivity 10 µm). The electric direct current was passed in vertical direction parallel with the axis of cylindrical mould or through the series circuit steel-powder nickel layer-hard alloy. If the cylindrical container (mould) did not have the upper punch (a load on top was absent), the sample after solidification had the form of a bullet. This sample became convex on top and concave on bottom. At the application of prepressing (start pressing) on top, the movement of suspension (molten matrix and solid particles) occurred in a similar way. Under the action of electromagnetic forces, a redistribution of solid particles in volume of suspension occurs. Particles with more high conductivity than liquid phase begin to cluster at the center. For the case of lower conductivity, the motion of the particles to the outer side surface of mould prevails. As the current passed through the series of circuit steel-nickel powder layer-hard alloy, three named parts of the circuit were sintered into a single block. After destruction at testing, the interlayer had the form of a ring. This shows the nonuniformity of the passing of electric current through the interlayer. The cause of displacements of solid (nonmolten) particles may be the simultaneous influence of thermic convection and squeezing out by the electromagnetic Lorentz-forces, which are directed radially. The phenomena described may be applied in the production of objects with a gradient (variable in volume) concentration of particles added specially. This refers to products of their interaction with molten matrix as well.