Magazine «Powder Metallurgy and Multifunctional Coatings. News ofHigher School»
Contents V. 4, 2012
POWDER PRODUCING PROCESSES AND PROPERTIES
Zherditskaya N.N., Yeremeeva Zh.V.
The effect of process factors on structure formation and propertiesof PK G13 powdered steel Report 1. The effect of non-uniformity of chemicalcomposition and porosity on structure formation and properties of PK G13powdered steel
The effect of initial porosity, powder grading of charge material,sintering time, carbon concentration, and content of non-metallic inclusion onthe structure and properties of PK G13 powder steel has been considered.Initial porosity is shown to introduce peculiarities in the process of plasticdeformation; in particular, a significant role in this mechanism can belong tograin-boundary slip. Elevated carbon concentration (up to 1,5 %) leads tocarbide formation during sintering and worsens the mechanical properties ofsteel. Increase of sintering time (as long as 120 min) and initial porosity(to 20–25 %) guarantees sufficiently high level of the mechanical properties ofsteel after hot forming at the expense of intensive reduction of oxides duringsintering.
Key words: powdered austenitic steel,chemical composition, porosity, hot forget.
POWDER PRODUCING PROCESSES AND PROPERTIES
Mamonova A.A.
Distinctive features of structure formation in the course of Kh18N15stainless steel alloying by chromium and manganese nitride
The effect of alloying of powdered Kh18N15 stainless steel withchromium and manganese nitrides on the structural state of ?-phase, which isthe basic component of nitride steels, has been studied using XRD analysis.Formation of complex nitrogen, manganese, and chromium solid solution in thematrix, which causes the distortion of crystalline lattice, has beenestablished. The quantitative characteristics of fine structure parameters,such as broadening of XRD lines and dislocation density, change similarly tothe crystalline lattice parameters of ?-phase depending on the process conditions.Precipitation of secondary nitrides from the solid solution results indecreasing the lattice parameter, quantitative characteristics of fine structure,and hardness of nitride steels.
Key words: hot-formed materials,chromium and manganese nitrides, solid solution, lattice period, linebroadening, dislocation density.
POWDER PRODUCING PROCESSES AND PROPERTIES
Vernigorov Yu.M., Frolova N.N.
Grinding time and screw drum charge dependence of granulometriccomposition of SmCo5 powder
SmCo5 powder grinding in the screwdrum placed in the generic interpole space of constant and variable fields ofelectromagnets has been experimentally investigated. The dependences ofgranulometric powder composition against the drum shape, grinding time, andcharge weight are found.
Key words: mill, magneto-shaking layer,ferromagnetic powder, granulometric composition, fine grinding.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Gorbushin A. V., Syrnev B. V., Rusin Yu. G.,Shevchenko G. M.
Investigation of the effect of pushing-outprocedure in forming powders on the quality of uranium dioxide articles
The results of pilot and analytical researches of the straincondition diagram near to pellet ends in its pushing out from the matrix afterpressing for establishing the reasons of cracking are given. It is shown thatfree surfaces can rise on green pellet end from the lower punch in pushing out;as a result, a dangerous boundary between the loaded and unloaded parts ofgreen pellet can be formed; this can lead to cracking at certain pressing procedures.Numerical investigations of establishing the maximum shear stresses in a greenpellet have been carried out in pushing out according to the standardregulation and with counter pressure. A technical proposal on expediency ofusing counter pressure is justified in pushing out after pressing of pelletsfrom uranium dioxide powders. It is established that application of counterpressure eliminates the formation of face cracks in green pellets in a widerange of pressing pressure and in using various binders as well as it opens theprospects for compacting powders without binder and green pellets withoutchamfers.
Key words: research, pellet, quality,article, formation, regulations, chamfer, binder, uranium dioxide, powder,crack, counter pressure, strained condition, pilot and analytical researches,maximum shear stresses.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Namazov S. N., Gamdullayeva I. G.
The effect of sintering process parameters on the structure andproperties of «iron–crude iron» powdered composition
The effect of sintering temperature and atmosphere on the structureand properties of «iron–crude iron» powder composition containing nickel-chromiumalloy powder in amount of 3,0 wt. % has been examined. The given compositiontakes on the best structure and properties at sintering temperature of1100–1150 °C.
Key words: alloy, iron–crude iron,structure, properties, powder composition.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Narva V. K., Marants A. V., Sentyurina Zh. A.
Study of laser building-up process of «steel–titanium carbide»powdered mixtures onto steel substrate
The effect of the main parameters of laser building-up (laserirradiation power, laser beam scanning speed over the surface to be processed,coating material powder consumption (SPN14A7M5 steel – titanium carbide (0?20vol. % TiC)), titanium carbide content in powder mixture) on the geometricalsizes (height, width, depth of fused base material) of built-up layer (bead)has been considered. The structure of built-up material has been studied withthe help of light microscope and SEM; hardness distribution from base materialto the built-up layer is found.
Key words: laser irradiation,building-up, steel, titanium carbide, mixture, microstructure, power, scanningspeed, powder consumption, built-up layer, algorithm of experiment.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Diachkova L. N., Kerzhentseva L. F.
Powdered carbon steel sintering process activation
Carbon diffusion activation processes into the iron basis in thecourse of powder steel sintering at the expense of using carbon-containingadditive in the form of thermally decomposable graphite, complex high-molecularcompounds, and alkaline metal compounds have been investigated. In is foundwith metallographic and radiometric analyses that introduction of theabove-stated additives allows obtaining homogeneous carbon distributionalready at sintering temperature of 900 °C. The additive of sodium bicarbonate increases the carbon diffusion speed 1,8, 1,5, and 1,2 times at temperaturesof 950, 1000, and 1100 °C respectively. Homogeneous structure ensures increaseof mechanical properties of powder carbon steels.
Key words: sintering, powder steels,activating additives, diffusion, structure, properties.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Panov V. S., Lopatin V. Yu., Myakisheva L. V., Malovik V. V.,Martynov V. V.
Fuel pellets on the basis of uranium dioxide alloyed by Al(OH)3and TiO2 nano-dispersed additives
The effect of alloying additives of Al(OH)3and TiO2 on the structure andproperties of fuel pellets on the basis of uranium dioxide has been studied. Itis found that their introduction improves the indices of macro- andmicrostructures of fuel pellets and positively affects their properties. Forexample, the grain size in a fuel pellet increases to 39 ?m (instead of 10–15?m by traditional technique), amount of large pores (> 10 ?m) decreases,strength and thermal conduction rises slightly.
Key words: fuel pellet, uranium dioxide,aluminum hydrate, titan dioxide, properties, microstructure, porosity,strength, thermal conduction, density.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Dorogina G. A., Balakirev V. F., Estemirova S. Kh.
Powdered soft magnetic materials of the Fe–Si–P system sintered innitrogen atmosphere (96 % N2 + 4 % H2)
Analysis of the physical properties of powdered soft magneticmaterial of the Fe–Si–P system sintered in vacuum and in hydrogen and nitrogenatmospheres (96 % N2 + 4 % H2) has been carried out. The effect of sometechnological parameters of annealing in nitrogen atmosphere on the propertiesof the resulting materials is considered. Sintering of soft magnetic materialpowder in nitrogen gas is shown to be promising. The service performances ofthe sintered materials (Нс = 116?110 А/m, ? = (33?110) • 10–8 ? • m, Вmax = 1.4?1.1 Т, Br = 0.65?0.35 T) are comparablewith the characteristics of soft magnetic materials sintered in more expensiveand potentially explosive environments, such as hydrogen. The material can beused for production of magnetic cores working in AC fields of industrialfrequency.
Key words: powdered soft magneticmaterials, physical properties, sintering atmosphere, process variables.
REFRACTORY, CERAMIC, AND COMPOSITE MATERIALS
Yelutin A. V., Belomyttsev M. Yu., Laptev A. A., Polushin N. I.,Sorokin M. N., Laptev A. I.
Structural investigations of diamond composites obtained by diamondgreen pellet infiltration near the line of thermodynamic equilibrium ofgraphite with diamond
Structure of diamond polycrystalline composite materials obtained bydiamond green pellet infiltration method by nickel-silicon alloys at pressureto 5,0 GPa and temperatures to 1800 K has been investigated. It is found thatthey consist of diamond framework and intercrystalline metal ceramic bond.Thus, the diamond framework is formed of diamond grains of initial size withweak diamond-diamond linkages; interganular space is filled by diamond chipsand metal ceramic bond. Formation of silicon carbide layers on diamond grain surfacesdefines the strength properties of diamond composites as a whole.
Key words: diamond composite materials,infiltration, bond, high pressures.
REFRACTORY, CERAMIC, AND COMPOSITE MATERIALS
Kontsevoy Yu. V., Ignatieva E. V., Pastukhov E. A.
Plastic deformation of layered steel–aluminum composite inasymmetric deformation zone
The possibility of obtaining the elevated strain-capacity layeredcomposite of the steel–aluminum system has been investigated. This problem hasbeen solved at the cost of additional deformation of the composite byrolling-drawing technique. With the help of metallographic researches it hasbeen shown that metal turbulence («rotational» deformations) occurs in thealuminum layer. The mechanisms of impact of traditional rolling androlling-drawing on the intermediate ferroaluminide layer are compared. It isfound that the plastic state of the composite in applying the rolling-drawingprocess is reached at considerably lesser degrees of high-altitude deformationas compared with the traditional rolling. Based on the conducted experiments,the optimal metal forming route has been established, which consists of acombination of traditional rolling and rolling-drawing.
Key words: layered composite,traditional rolling, rolling-drawing, intermetallide fragmentation,high-altitude deformation, metal turbulence.
POROUS MATERIALS AND BIOMATERIALS
Fedotov A. F.
Continuum model version of viscous deformation of porous materialsReport 1. Microscopic viscous stress and strain average-out technique
A continuum model of hot deformation of porous powder materialsaccounting for non-uniform character of the viscous flow of hard phase isconsidered. The distinctive feature of the model lies in the fact thataverage-out of microscopic stresses and strains is executed not over the wholevolume of the hard phase but over a certain effective volume. The theoreticaldependences for describing the regularities of hot deformation of powder materialsare given: defining relations at the exponential law of stationary creep ofhard phase material; density dependence of portion of the effective volume ofthe average-out; density functions of shear- and volume-viscosity coefficientof porous material.
Key words: porous material, hotdeformation, average-out volume, density function.
POROUS MATERIALS AND BIOMATERIALS
Gorina V. A., Cheblakova E. G., Zolkin P. I.
The effect of thermal treatment conditions on specific surface areaand porous structure of viscose based carbon fibers
Specific surface area (Ssp) andporous structure of carbon fibers on the basis of viscose of the KrasnoyarskFactory of Chemical Fibers have been investigated by method of low-temperatureadsorption of nitrogen using ASAP 2020 device. Fiber thermal processingtemperature dependence of Ssp value (ttp = 1200?2000 °C) is shown as well as the effect of gas-phase activation conditions in СО2 flow is considered at ta = 900 °C on the porous structure of fibers. It is found thatreduction ttp and increase in fiber activationtime result in the growth of Ssp and thedevelopment of microporous structure.
Key words: activated carbon fibers, specificsurface area.
NANO-STRUCTURED MATERIALS AND FUNCTIONAL COATINGS
Pervushin D. A., Shishkovsky I. V., Smurov I. Yu.
Gas-dynamic spray deposition of hydroxyapatite coatings on medicalinstruments made of titanium alloys
Hydroxyapatite powder was used to spray deposition coatings ontotitanium alloy based medical instruments. Earlier determined deposition processparameters are improved for the purpose of obtaining proper hydroxyapatiteadhesive with substrate. The multi-zone nature of sprayed microstructures isshown from the results of optical microscopy and scan electron microscopicstudy associated with energy-dispersive X-ray (EDX) spectroscopy.Hydroxyapatite after spraying is shown not to suffer essential changes, beingimportant for medical applications.
Key words: cold and detonation spraying,hydroxyapatite ceramic, titanium alloys, nitinol, medical instruments.
CHRONICLE
Jubilee of Vladimir Vladimirovich Kudinov
INFORMATION
On «Russian nanotechnologies and developments in the field ofautomotive and machine-building industries» seminar-exhibition
