Structure and mechanical properties of a nonmagnetic high-nitrogen corrosion-resistant 05Kh22AG15N8M2F cast steel produced by high-gradient directional solidification

The structure and properties of an austenitic high-nitrogen corrosion-resistant 05Kh22AG15N8M2F cast steel produced by high-gradient directional solidification (HGDS) and equiaxed-grain solidification (ES) have been studied and compared. In contrast to ES, HGDS allows one to substantially decrease the degree of dendritic segregation of alloying elements, to eliminate porosity, and to increase the strength and plasticity of the steel.     

Effect of heat treatment on the structural transformations and properties of high-nitrogen chromium steels

Conclusions  

Improving the precipitation of arsenic trisulfide from washing waters of sulfuric-acid production of copper smelteries

Disadvantages of the sulfide method of purifying washing waters of the sulfuric-acid production are the formation of finely dispersed (particle size from 0.3 to 1.5 μm) difficult-to-filter precipitates of arsenic(III) sulfide and the danger of isolation of hydrogen sulfide into the atmosphere upon an overdose of sodium hydrosulfide. The coagulation of sols of arsenic sulfide is investigated in order to develop more efficient and rapid filtration technology of the precipitate. The filtration rate in various supply modes of sodium hydrosulfide and the dependence of settling rate and filtration on the presence of coagulants such as iron sulfate and aluminum sulfate are determined. It is established that the implementation of the distributed supply of sodium hydrosulfide during the precipitation of arsenic sulfide in combination with the application of such inorganic coagulant as iron(III) sulfate will make it possible to increase the particle size of the As₂S₃ phase by a factor of several times and increase the filtration and settling rates of pulps.     

High-temperature X-ray diffraction study of phase transformations in nitrogen-bearing steels

The phase composition, lattice parameters, and residual stresses in the α and γ phases of steels containing 0.14–1.2 wt % N are determined by high-temperature X-ray diffraction at 20–1200°C. A procedure is proposed for the in situ quantitative study of the Cr₂N nitride dissolution kinetics and austenite grain growth when diffraction patterns are taken at high temperatures. The temperature boundaries of the decomposition of the α and γ phases and the temperature of complete dissolution of nitride phases are found. The formation of interphase residual stresses during thermal treatment is considered.     

Effect of the heat treatment and plastic deformation of high-strength corrosion-resistant nitrogen-bearing steels on their wear resistance during sliding friction

Wear-resistance sliding-friction tests of high-strength corrosion-resistant nitrogen-bearing 08Kh14AN4MDB and 05Kh22AG15N8M2F steels have been performed for different structural states under sliding-friction conditions. The wear resistance of these steels depends on the intensity of the strain hardening of austenite. The martensitic-austenitic 08Kh14AN4MDB steel has a higher wear resistance if it has a high nitrogen-austenite concentration. The dependence of the weight loss of the 05Kh22AG15N8M2F and 12Kh18N10T steels on the test time is found to be linear.     

Structural and electrical properties of the Ge x Si1−x /Si heterojunctions obtained by the method of direct bonding

The results of studying the structural and electrical properties of structures produced by the method of direct bonding of Ge _x Si_1?x and Si wafers are reported. The wafers were cut from the crystals grown by the Czochralski method. Continuity of the interface and the crystal-lattice defects were studied by X-ray methods using synchrotron radiation and by scanning electron microscopy. Measurements of the forward and reverse current-voltage characteristics of the p-Ge _x Si_1?x /n-Si diodes made it possible to assess the effect of the crystallattice defects on the electrical properties of heterojunctions. Satisfactory electrical parameters suggest that the technology of direct bonding is promising for the fabrication of large-area Ge _x Si_1?x /Si heterojunctions.     

Analysis of charges and surface states at the interfaces of semiconductor-insulator-semiconductor structures

A method for determining the energy spectrum of charges and surface-state densities at the interfaces of semiconductor-insulator-semiconductor structures was developed; the method is based on the analysis of capacitance-voltage characteristics. The method was experimentally tested with Si-SiO₂-Si structures prepared by direct bonding of both mirror-polished smooth wafers and wafers with a regular mesoscopic relief pattern at the inner surface of the wafers to be bonded. The density of surface states is lower at the surfaces with a regular relief pattern than that at the surfaces without the surface relief.     

Mechanisms of molecular interactions in polybase–polyacid complex formed by copolymers of N,N‐dimethylaminoethylmethacrylate with alkylmethacrylates and methacrylic acid with ethylacrylate

Mechanisms of molecular interaction in the blends of a polybase, a copolymer of N,N‐dimethylaminoethylmethacrylate with methylmethacrylate and butylmethacrylate (PDMAEMA–MMA/BMA), with a polyacid, a copolymer of methacrylic acid with ethylacrylate (PMAA‐co‐EA), and plasticizer, triethylcitrate (TEC), have been investigated with FTIR Spectroscopy and potentiometry. To evaluate the strengths of hydrogen and ionic bonds in the polyelectrolyte complexes, quantum‐chemical calculations were performed. According to this analysis, the energy of ionic and hydrogen bonding diminishes in the order: multi‐component complexes involving protonated aminogroup of DMAEMA (ammonium cation) in the presence of chlorine counterion with ionized or unchanged carboxyl groups and water molecules (690–520 kJ/mol) > ternary H‐bonded acid‐base complexes associated with molecule of water (520–420 kJ/mol) > binary ionic complex of carboxylate anion and ammonium cation (404 kJ/mol) > H‐bonded complex of carboxylate and ammonium ions (257 kJ/mol) > binary H‐bonded complex of uncharged carboxyl group with ammonium cation (114 kJ/mol) > ternary H‐bonded complex of uncharged carboxyl group, aminogroup and water molecule (43 kJ/mol) > binary H‐bonded complex between nonionized carboxyl and amino groups (26 kJ/mol). Proton‐donating capability of functional groups in the studied polyelectrolyte blends diminishes in the order: HN⁺(CH₃)₂ ? > HOOC? > HO? . The proton‐donating capacity can be significantly improved in the presence of Cl^? ions, the effect of which may be appreciably inhibited if Na⁺ cations are available in the blend or solution. Proton‐accepting capability weakens in the order: uncharged aminogroup > carboxylate anion > uncharged carboxyl group > hydroxyl group. The results of quantum chemical calculations facilitate interpretation of FTIR spectra. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Parametric optimal control problems with weighted <Emphasis Type="Italic">L</Emphasis><Subscript>1</Subscript>-norm in the cost function

In the paper, an optimal control problem with weighted L ₁-norm in the cost function is studied. The problem is considered as a parametric problem where L ₁-norm weight ratio is treated as a parameter. We analyze the dependence of solution to the mentioned optimization problem on values of the parameter. A theorem that describes properties of the solution under small parameter perturbations is proved. Differential properties of the solution are investigated. Under assumption that a solution to unperturbed problem is known, rules for construction of solutions to perturbed optimization problems are given.