Influence of the coking properties of coal batch on coke properties

At OAO Zapadno-Sibirskii Metallurgicheskii Kombinat (ZSMK), research is undertaken to improve the optimization of coking batch. The basic approach, proposed by specialists from OAO Nizhne-tagil’skii Metallurgicheskii Kombinat, employs the coefficient K _opt, which characterizes the deviation of the batch from its optimal composition. The coking properties of the OAO ZSMK coal batch over the last few years are analyzed. After laboratory and industrial coking of batch with different K _opt, the strength and reactivity of the resulting coke is investigated. Evaluation of coke-grade coal in terms of its rank according to State Standard GOST 25543-88 proves inadequate, since coal of the same rank may differ markedly in coking properties. A method is established for assessing the optimality of the coal batch at OAO ZSMK.     

Critical parameters of the vapor-liquid-solid growth of silicon whiskers

We have determined critical parameters that restrict the vapor-liquid-solid growth of silicon whiskers. We demonstrate that there are maximum and minimum critical radii for whisker growth and identify boundary conditions that lead to solvent droplet breakdown and crystal branching.     

Features of the Decomposition of Delta Ferrite in Nitrogen-Containing Austenitic Steels

Features of the decomposition of the ferromagnetic δ ferrite with the formation of nonferromagnetic constituents (γ and σ phases) at temperatures of 900–1200°C in a nitrogen-containing austenitic steel have been determined. The transformation of δ ferrite at high temperatures (1100–1200°C) occurs with the formation of Widmanstäatten austenitic crystals in the ferritic matrix. At lower temperatures (900–1000°C), the transformation of δ ferrite develops by discontinuous decomposition with the formation of colonies of alternating plates of paramagnetic γ and σ phases. In the course of formation of the nonferromagnetic state as a result of the decomposition of δ ferrite at 900–1000°C (for 1 h), a subgrain structure with an increased density of dislocations, which is typical of thermomechanical treatment, is retained in the steel previously strengthened by high-temperature deformation.     

Effect of the electronic structure of metal solvents on silicon whisker growth

We have analyzed and systematized available data on silicon whisker growth with the use of a wide variety of metal solvents. The catalytic properties of metals responsible for stable Si whisker growth are shown to depend on the position of the metal in the Periodic Table, the interaction between the molten metal and silicon, and the number of electrons in the s and (n − 1)d electron orbitals of the metal. The most stable silicon whisker growth is ensured by Cu, Au, Ni, Ag, Pd, and Pt particles.     

Formation of nanosized ferromagnetic phases during plastic deformation and subsequent annealing of stable austenitic steels

The effect of severe plastic deformation on the destabilization of the g phase in metastable and stable austenitic steels is considered. An increase in the degree of deformation and a decrease in the deformation temperature were shown to lead to the formation of a ferromagnetic phase in the materials under study.     

Effect of the line tension at the vapor-liquid-solid boundary on the growth of silicon nanocrystals

We examine the thermodynamic aspects of the effect of the line tension at a bent vapor-liquid-solid boundary on quasi-one-dimensional growth of silicon nanowires. Experimental data demonstrate that there is a limiting size of solvent nanodrops below which they cannot exist in equilibrium and that there is a limiting nanowire diameter starting at which the increase in line tension with decreasing diameter prevents nanocrystal growth at a given supersaturation.     

Using an intermediate nanocrystalline γ phase for producing austenitic steels with a controllable thermal expansion coefficient

The metastable austenitic iron alloy with 31.3 wt % Ni (N31) has been used to show the possibility of the formation of a nickel-concentration inhomogeneity in a fine-grained austenite due to an α → γ trans-formation under the condition of a preliminary formation of a nickel-enriched intermediate nanocrystalline γ phase. The thermal expansion coefficients (TECs) in the range of ?100 to +300°C have been estimated in concentrationally inhomogeneous steel N31 after various heat treatments. The conditions necessary to ensure the possibility of controlling the TEC in wide limits have been found.