Powder production processes and properties
Antsiferov V.N., Khramtsov V.D. Morphology of powders and rheology of stabilized suspensions
The relation between the rheological properties of stabilized suspensions of dispersed metallic powders and their morphological characteristic properties has been analyzed. Stabilized suspensions are shown to be attributed to pseudoplastic systems, and their concentration ability directly depends on relative density after bumping-down.
Kostikov V.I., Dorofeev Yu.G., Yeremeeva Zh.V., Zherditskaya N.N., Ulianovsky A.P., Sharipzyanova G.Kh. Some distinctions of applying unconventional carbon-containing components in powdered steel production process. Report 1. The effect of unconventional carbon-containing components on the processes of charge material preparation and powdered steel rough piece compaction
The article shows a possibility of reducing the costs of hot-deformed powder carbon steel production at the expense of using unconventional carbon-containing components (special low-ash artificial graphite, pyrolized carbon, high-temperature coal-tar pitch) in the composition of charge material. Special features of their chemical and granulometric composition, crystalline structure as compared with traditionally used pencil lead stipulate improvement of charge material uniformity and density of cold-pressed compacts and finely the improvement of powdered steel properties.
Theory and processes of powder material forming and sintering
Oglezneva S.A., Mikhailov A.O., Zubko I.Yu. The effect of carbon on structure formation during mechanical alloying and sintering of powdered steels
The structure and properties of steels prepared from thermodynamically unstable powders with high dislocation density, cellular dislocation structure, and refined subgrains have been investigated. The thermodynamic instability of the powders was produced by mechanical carbon alloying of iron. The structure of the powders was inherited by sintered steels, and physical-mechanical properties grew with increasing the quantity of added mechanical energy and carbon content. The strengthening mechanism is connected to the formation of cellular dislocation structure in iron with its mechanical carbon alloying.
Self-propagating high-temperature synthesis (SHS)
Fedotov A.F. Consistent patterns of compaction and shaping during SHS-compaction with loose shell
The consistent patterns of compaction and forming of flat blanks produced by SHS-compaction with loose shell have been investigated by the calculated-experimental method. The specific characters of hot solid-liquid end-product compaction kinetics are analyzed. A mathematical model of forming was proposed for SHS-compaction of flat blanks. The consistent patterns of loose shell deformation and compaction are studied. The effect of shell dimensions and mechanical properties on the consistent patterns of SHS-blank compaction and forming was estimated. The techniques of improving the quality of SHS-compacted flat blanks are given.
Surface modifying, including by charged beams, photon and plasma fluxes
Bleikher G.A., Krivobokov V.P. Technological possibilities of power pulsed ion beams for erosion machining of metal surfaces
Technological possibilities of submicrosecond (10–9–10–6 s) ion beams in the range of power density 106–109 W/cm2 and particle energy 1–2000 keV as well as the metal surface erosion mechanisms in their effecting have been analyzed. The collective processes connected with radiation heating are shown be of great importance. A model for description of erosion is proposed. As per the model, the target atom flow leaving the surface irradiated consists of two independent components formed as a result of colliding sputter and evaporation. The effect of irradiation on erosion coefficient and sputter to evaporation factors ratio was analyzed.
Tashlykov I.S., Baraishuk S.M. Elementary composition, topography and wettability of graphite surface modified by ion-assisted deposition of chromium coatings
Investigation of composition, topography, and wettability of the graphite surfaces modified by ion-assisted deposition of ~300-1000 nm Cr-coatings has been conducted using Rutherford backscattering technique, atomic force microscopy, and wetting angle measurements. It is shown that the Cr-based coatings produced by means of SIAD contain, besides Cr atoms, hydrogen, carbon, and oxygen from the residual gases of the vacuum chamber (because of incomplete pumping out) and 1–2 at. % silicon diffusing from the graphite. As it has been observed, the surface roughness increases with deposited coating thickness. This effect is considered as the main factor being responsible for the growth of hydrophobic properties of modified graphite surfaces.
Nano-structured materials and functional coatings
Ryzhonkov D.I., Levina V.V., Dzidziguri E.L., Khrustov E.N. Property regulation of nanosized metal-oxide powders by introduction of dispersing agents
The effect of additives of hard-reducing oxides Al2O3 and MgO on dispersiveness and morphology of metal-oxide nanosized compositions on the Ni and Cu bases during their production by chemical methods has been considered. The conditions of directional synthesis of metal-oxide nanopowders (taking the nature and amount of oxide phase into account), production of precursors and the kinetic characteristics of their metallizing are formulated. The regularities found create the preconditions for directional formation of metal-oxide nanopowders with the set particle size and the composition by chemical-dispersion methods.
Blagoveshchensky Yu.V., Levinsky Yu.V., Voldman G.M. Tungsten nanopowder coagulation during annealing in hydrogen
Tungsten nanosized particle coagulation has been investigated during annealing in flowing hydrogen at temperatures of 600–1000 оС and holding time within 1 h. The main coagulation mechanism was found to be the transport through gas phase, and WO3·H2O molecules are mass carriers. The estimation calculation of coagulation rate has been carried out and their good fit to the experimental data has been shown. The recommendations are given to optimize the conditions of heat treatment of tungsten nanopowders.
Terekhova O.G., Itin V.I., Magaeva A.A., Naiden E.P., Ivanov Yu.F., Maksimov Yu.M., Boldyrev V.V. Mechanochemical synthesis of nanosized ferrite powders from salt systems
Nanosized spherical powders of oxide cubic ferrimagnetic materials have been produced by mechanochemical synthesis. Their phase composition, morphology, dispersiveness, structure, and specific surface as well as magnetic properties were measured. The ferrites synthesized are found to be nanosized powders of high-developed surface (S = 100-160 m2/g), and their magnetic characteristics are significantly different from those of bulk ferrites. When reducing the structural element from 1000 to ~3-16 nm, ferrimagnetic materials gather the properties of cluster spin glass with high interlocking temperature.
Information
Dorofeev Yu.G. Establishment, formation, and prospects for the development of Novocherkassk Scientific School in the field of studying functional powdered materials
The results of activity of Novocherkassk Scientific School concerning the production of high-density functional powder materials are presented. In the late 1950s the pioneering studies on hot briquetting of metallic chip through dynamic loading were performed in Novocherkassk. The devised technique was subsequently designated as dynamic hot pressing in the home literature and as powder forging in the foreign one. The technique was taken up as dependable and efficient method of production of high-density powder materials used for various functional purposes. Works at the study of compaction, deformation, and interparticle joining on hot repressing of porous powder preforms make up the essentials of the technique. At present basic and application-oriented investigations are pursued in the context of grants of the Ministry of Education and Science of Russia as well as for the needs of some enterprises.
- Ligachev A.E. 7th International Conference "Interaction of Irradiation with Solid Body"
- Ligachev A.E. VI All-Russian Scientific and Technical Conference "Fast-Quenched Materials and Coatings"
