Powder producing processes and properties
Ryzhonkov D.I., Lyovina V.V., Chuprunov K.O., Lysov D.V.
Kinetic regularities of reduction of oxide and hydroxide powder materials on the basis of iron, nickel, and copper with different dispersiveness
Kinetic peculiar properties of joint reduction of two- and three-component oxide and hydroxide powders on the basis of Fe, Ni, and Cu of different dispersiveness have been considered. The established regularities allow to create suppositions for object-oriented synthesis of metallic nanomaterials of complex composition by chemical methods.
Key words: reduction, iron, nickel, copper, oxides, interfacial interactions, dispersiveness, kinetics, nanomaterials
Antsiferov V.N., Gorbachyov I.I., Oglezneva S.A., Popov V.V.
Structural and phase composition and properties of mechanically alloyed high-nitrogen powder steels
The structure and properties of the Fe–21%Cr–N and Fe–18%Cr–7%Ni–0,8%Mn–0,5%C–N powder systems mechanically alloyed in nitrogen atmosphere and steels sintered from the powders in dissociated ammonia at t = 1170 °C have been investigated. The thermodynamic calculations of the phase compositions of the steels are carried on the basis of searching the Gibbs integral energy minimum for the system. In comparing the obtained experimental data with the results of thermodynamic calculations for the Fe–Cr–C–N and Fe–Cr–N systems, it is found that the equilibrium phase composition is not reached. The resulted steels contain increased nitrogen quantity (1,6 to 2,1 %) distributed in austenite and/or nitrides. The steels have high strength, wear and corrosion resistance.
Key words: powder steel, mechanical alloying, structure, properties, austenite, nitrides, thermodynamic calculations, equilibrium diagrams.
Theory and processes of powder material formation and sintering
Fedotov A.F.
Local stress and strain model and effective elastic moduli of powder and porous sintered materials
A microscopic strain and deformation averaging model is proposed to take account of heterogeneous deformation of solid phase of powder and porous sintered materials. Unified functional dependence of relative shear modulus and yield strength in shear on porosity is confirmed theoretically and experimentally. Elastic and plastic stress averaging is shown to be implemented for the same volume. Analytical density dependences of volume averaging as well as effective shear moduli and volume compression are proposed. A good conformity of calculated and experimental data is obtained for elastic moduli of powder and porous sintered materials.
Key words: powder material, porous sintered materials, averaging volume, elastic moduli.
Self-propagating high-temperature synthesis
Borovinskaya I.P., Prokudina V.K., Ratnikov V.I.
Application of titanium in SHS-processes
A review on application of different titanium types in technological SHS-processes is given. Ti-types are powders of different origin, sponge, dioxide (rutile concentrate and pigment powder) as well as waste: chips and dross. By the example of combustion of solid–solid and solid–gas systems (titanium–carbon and titanium–nitrogen), the effect of the major characteristics of titanium on the properties of final SHS-product is shown. The principles are validated of selecting titanium for SHS-processes to be determined by the following factors: chemical and granulometric compositions, morphology of particle surface, fire-and-explosion safety as well as price and availability of various titanium types. Methods of Ti-powder production are briefly considered, which are based on the SHS processes, namely, magnesium-thermic reduction of dioxide followed by acid enrichment and SHS-hydrogenizing of sponge followed by dehydrogenation. A short list of ranges of use of some SHS-products on the titanium basis is presented.Key words: titanium, powder, sponge, titanium dioxide, waste of titanium (chips, dross), SHS-processes.
Refractory, ceramic and composite materials
Ivanov D.A., Ivanov A.V., Shlyapin S.D.
Physical-chemical aspects of technology of laminated Al2O3–Al cermet produced by reaction sintering method
The article considers some peculiar properties of laminated Al2O3–Al cermet produced by reaction sintering of powder blank parts in the air, which have been obtained by compression of aluminium powder (PAP-2) with plate-like shape of particles. The reaction sintering process was activated by introduction of dry residue of liquid glass (C = 3?28 %) into the charge mixture. According to the data of roentgenofluorescence, the sintered material contains (vol. %) Al (61–82), γ-Al2O3 (8–25), Na2Si2O5 (2–15), and Si (1–14). Oxide phases and silicon are nanosized morphological objects (13–100 mm) in laminated aluminum matrix. Cermet density is 2,1–2,45 g/cm3, tensile strength is 45–90 MPa, and maximum bending strength is 320 MPa. Reaction sintering activation with small additive of dry residue of liquid glass (3 %) keeps laminated cermet structure. It is levelled down in significant increase of reaction sintering time (as high as 600 min) or C (as high as 28 %) because recrystallization and involving aluminium plate-like particles in chemical interaction.
Key words: cermet, composite material, aluminum–aluminum oxide, laminated structure, phase composition, compression, technological binding material, liquid glass, pelletization, charging material, reaction sintering, filtration combustion, powder process, shrinkage, strength, density, precipitation strengthening.
Surface modifying, including by charged beams, photon and plasma fluxes
Gadalov V.N., Romanenko D.N., Samoilov V.V., Nikolaenko A.V., Grigoriev S.B.
Electrospark coating roughness assessment technique after burnishing with mineral ceramic
Using the complex parameter (Δ), surface roughness assessment technique of metal-cutting tools strengthened by local electrospark application of coatings followed by burnishing with mineral ceramics VOK-60 has been analyzed. A device is proposed and the principle of its operation is described for burnishing of cylindrical, conic, and end surfaces on turning group machine-tools. The optimal conditions of burnishing with mineral ceramics to ensure maximum durability of smoother and required roughness parameter are established.
Key words: surface, roughness, burnishing, mineral ceramics, coating.
Application of powder materials and functional coatings
Gordeev Yu.I., Zeer G.M., Zelenkova E.G., Abkaryan A.K., Surovtsev A.V., Teremov S.G. , Plotnikov N.P.
Prospects of nanoparticle application in contact materials of urban electric transport
The results of studying silver and copper based electrocontact materials and modified nanoparticles are given. Their optimum compositions, technological characteristic properties of manufacture, physical-mechanical and operational properties, and microstructure have been studied. The possibility of replacing standard, widely applicable electrocontact materials and Ag-containing products by copper-based pseudoalloys with additives nanoparticles is shown. Innovation prospects of the results of studies are considered.
Key words: nanoparticles, nanopowders, electric materials, electric contacts, silver, copper.
Chronicle
Galevsky G.V., Rudneva V.V.
Professor O.I. Leipunsky and diamond synthesis
(to 100-year anniversary of birthday)
Professor O.I. Leipunsky’s creative inheritance has been analyzed. For the first time in 1939, Leypunsky theoretically predicted the parameters and conditions of synthetic diamond production. An assessment of the scientific and technical results of this great invention is given.
Key words: graphite, diamond, synthesis, temperature, pressure, state diagram.
Basov Vladimir Valentinovich (1948–2010)
