Powder production processes and properties
Kasimtsev A.V., Reutova N.P., Mnasina L.M., Zubkov N.P., Sviridova T.A., Turutin Yu.A.
Structure, properties, and production of "Zial" powder alloy for gas absorbers
The results related to the development of calcium-hydride process of producing powdered Zr–16Al alloy known as "Zial" are given. As against to the powders produced by grinding cast alloy, calcium-hydride powders are more dispersed and have highly-developed particle surface. A sorption-capacity determining technique has been developed for "Zial" alloy in hydrogen. It is found that calcium-hydride powders are not inferior to those produced from cast alloy in this value but, as to carbon oxide sorption, they are better. X-ray phase analysis shows the phase composition of gas absorbers made of the calcium-hydride powders of Zr–16Al alloy consists mainly of Zr3Al2, Zr5Al3 and Zr4Al3 intermetallic compounds, being optimal in applying "Zial" alloy as getters.
Key words: gas absorbers, getters, calcium-hydride technique, powder alloy, gases, phase composition, structure, intermetallic compounds, sorption capacity.
Ignatiev I.E., Kontsevoi Yu.V., Ignatieva E.V., Pastukhov E.A.
On the factors determining the density of powder compacts
The given research presents, on the basis of theoretic analysis of metallic powders behavior during compaction, the factors, which determine powder compact density: compacting pressure, sizes of a powder particle and its grain. The mechanisms affecting these factors have been also examined here and the mathematical dependence allowing forecasting the compact density has been derived. Using the experimental data of other authors, the examination of the derived formula has been carried out in a wide range of varying sizes of compacted dispersoids.
Key words: powders, particle grain size, powder particle size, compact density, relative density, strain resistance.
Rakova N.N., Yedrennikova E.E., Vorobiyova M.V., Ivanov V.V.
Production of high-purity microcrystalline molybdenum and rhenium powders by reduction in hydrogen-nitrogen media
Opportunities of producing high-purity microcrystalline molybdenum and rhenium powders by direct single-stage reduction of ammonium compounds of molybdenum ((NH4)6Mo7O24·4Н2О) and rhenium (NH4ReO4) in hydrogen-nitrogen media are analyzed. Based on examining the results of investigation of the complex effect of the process parameters (degree of cleaning starting reagents, temperature, gas mixture composition, reagent feed rate) on the quality of metal powders to be produced, the optimum reduction process performance to produce microcrystalline molybdenum and rhenium powders of high purity has been developed.
Key words: powder, molybdenum, rhenium, ammonium paramolybdate, reduction, hydrogen-nitrogen steam-gas media.
Theory and processes of powder material forming and sintering
Antsiferov V.N., Grevnov L.M., Torsunov M.F.
Structure formation in the process of sintering of α-Fe–C60 and α-Fe–nanotubes compositions
The formation of α-Fe–C60 and α-Fe–nanotube powder composition structure in the course of sintering at temperatures of 650 and 880 °С has been investigated. Concentration of fullerenes and nanotubes was varied from 1 to 2 wt.%. Specimens were compacted at pressure of 600 MPa. A part of fullerene is shown to pass into graphite in the course of α-Fe–C60 and another part interacts with iron resulting in FexC60 fullerene-containing phases. The fullerene decomposition process at 880 °С progresses more actively than at 650 °С. It was found that a part of nanotubes decomposes in sintering iron-nanotube compositions at t = 650 and 880 °С with formation of fullerene-containing phases, the process proceeds is more active at 650 °С than at 880 °С. Increase in the quantity of nanotubes introduced into the compositions promotes the fullerene synthesis.
Key words: powder metallurgy, powder compositions, synthsis, phase, structure, fullerene, nanotubes.
Self-propagating high-temperature synthesis (SHS)
Levashov E.A., Pogozhev Yu.S., Rogachyov A.S., Kochetov N.A., Shtansky D.V.
SHS of composite targets based on titanium carbonitride, silicide, and alumonitride for long-plasma deposition of multifunction coatings
Macrokinetic features of the Ti–Al–Si3N4–C system mixture combustion process to form compact ceramic material (CCM) the composition of which is described by general formula: X(TiAl3) + (100 – X)(0,448TiC0,5 + 0,552(Ti5Si3 + 4AlN)) with burdening parameter Х = 10?50 % have been studied. CCM samples in which TiCxNy grains and TiAl3 and Ti5Si3 binding phases are the main structural components have been produced. Increase in X results in formation of Мn+1АХn-phases of Ti3SiC2 composition in the synthesis products. Complex investigations of physical-mechanical properties of produced ceramic material were carried out. The obtained results were used for deriving the inverse relation of density and hardness of compact materials on X parameter. Heat-resistance tests of samples show the produced CCM on the basis of titanium carbonitride, silicide, and aluminide have excellent withstandability against high-temperature oxidation: their oxidation rate in the air at t = 900 °С for 30 h does not exceed 7,8·10–5 g/(m2·s).
Key words: self-propagating high-temperature synthesis, compact ceramic materials, composite cathode-targets.
High-melting, ceramic, and composite materials
Kulmetieva V.B., Kachenyuk M.N., Porozova S.E., Krasny B.L., Tarasovsky V.P., Krasny A.B.
Production of zircon based ceramic material
A comparative characteristic of behavior of zircon concentrates obtained from different producers has been carried out in producing ceramic on their basis. Impurities are shown to affect not only thermal zircon dissociation but the processes proceeding in sintering. Application of the techniques of cold uniaxial and cold isostatic compaction affects ambiguously the strength characteristrics of the ceramic on their base. Fractographic analysis of the fracture surface of zircon ceramic shows the material strength to be determined to a large extent by precipitation of varied-composition phase consisting of SiO2, ZrO2 and Al2O3.
Key words: zircon, zircon concentrate, thermomechanical analysis.
Ordanian S.S., Orekhov A.N., Vikhman S.V.
On interaction of W2B5 with MeIV, VC carbides
It has been found that W2B5–MeIV,VC section in the W–B–C–MeIV,V quaternary systems is quasi-binary and polythermal sections are described by eutectic equilibrium diagrams. The composition and temperature of the eutectic correlate with carbide melting temperature; MedC content varies from 50 mol.% in the W2B5–VC system to 4–6 mol.% in W2B5–TaC. Existence of the MedC–MedB2–W2B5 ternary eutectic systems being prospective for development of new ceramics is certified.
Key words: polythermal section, W2B5 carbides, eutectic, equilibrium diagram.
Porous materials and biomaterials
Artyukhova N.V., Monogenov A.N., Yasenchuk Yu.F., Gyunter V.E.
Features of porous titanium nickelide structure during reaction sintering with addition of aluminum
Porous cylindrical samples of titanium nickelide based alloy containing 0,5, 1,5, and 2,0 at.% Al and having sizes of 2,5?30 mm were obtained by sintering in two stages: first - solid-phase sintering at temteratures up to 900 °С, second - liquid-phase sintering at t > 1000 °С. On the assumption of existing knowledges of reaction diffusion in the Ti–Ni–Al system, the structure of obtained alloy was analyzed. Scanning electron microscopy and microX-ray spectral analysis found that multiphase alloy is formed in the course of the first sintering; the alloy contains isolated areas of TiNi phase the segregation of which prevents the propagation of the front of martensite phase transformation in the finished sample. The heterophase structure of Ti50Ni50–хAlх porous sample being formed after the first sintering become more uniform after the second sintering at higher temperature.
Key words: porous titanium nickelide, Ti–Ni–Al system, liquid-phase reaction sintering, solid-phase reaction sintering, heterophase structure.
Process and material quality control
Kem A.Yu.
Development of environmentally oriented processes to produce articles from aluminum powders by powder metallurgy.
Report 2. Development of ecologically safe process of fine aluminum powder compaction
It is shown that introduction of liquid film-forming lubricant into aluminum powder structure and the use of warm compaction make it possible to improve the ecological safety of the processes related to the powder metallurgy of aluminum by reducing dust-forming ability of fine powders, raising transportable properties of compacts, and eliminating the operation of process lubricant removal from the compact volume at the sintering stage.
Key words: fine powder, aluminum, film-forming lubricants, compaction, sintering, ecology.
Information
Koftelev V.T., Korzhankova G.A., Rusyaev A.A., Shishkina I.P., Romanova L.V., Mozgova O.V., Volchok V.O., Popova T.I.
Features of production of small-sized powder parts
