Magazine «Powder Metallurgy and Multifunctional Coatings. News ofHigher School»
Contents V. 3, 2012
POWDER PRODUCING PROCESSES AND PROPERTIES
Dorofeyev Yu.G., Lipkin M.S., Naumenko A.A., Rybalko E.A., Sirotin P.V.,Ivashin I.N., Lipkin V. M.
Copper powder production from ammoniateelectrolytes and theirproperties
The opportunities of receiving ultrafine copper powders fromammoniate electrolytes on the basis of the effects caused by presence ofammonium ions are considered. It is found that chemical reduction of coppertakes place on the anode at the expense of formation of hydrazine-strongreducer in the volume of ammoniate electrolytes.
Key words: ultrafine copper powder,production of copper powder, copper-containing waste processing, ammoniate electrolytes,vibrating electrode.
POWDER PRODUCING PROCESSES AND PROPERTIES
Antsiferov V. N., Grevnov L. M., Torsunov M. F.,Boyarshinov V. A.
Structure of fullerene-containing deformed powdered steels
The effect of dynamic hot compaction (DHC) and intensive plastictorsional deformation (IPTD) on the structure and propertiesfullerene-containing powdered compositions of Fe–graphite and Fe–pig-iron hasbeen investigated. It is found that sintering of Fe–graphite samples results inthe synthesis of fullerenes in their surface layer, and fullerene-containingphase is observed in their volume after DHC too. DHC results in increase ofwear resistance of the Fe-graphite composition. It is shown that 6.16 A* lineappears on diffractograms of all examined samples (both Fe- graphite andFe-pig-iron) as a result of IPTD. The scanning probe microscopy found theelasticity modulus of samples iron-graphite increases from 50–58 to 67–91 GPaand local hardness increases from 10–19 to 137–155 GPa because of IPTD. The elasticitymodulus of iron-pig-iron samples also increases from 63 GPa before IPTD to55–109 GPa after that. A wide scatter in values of this index testifies ofinhomogeneity of the structure formed in the course of deformation.
Key words: fullerenes, powdermetallurgy, deformation, synthesis, sintering.
POWDER PRODUCING PROCESSES AND PROPERTIES
Pribytkov G. A., Korzhova V. V., Kasterov D. S.
Oxidation and structural transformation in powderedaluminum-based compacts in heating in the air
Oxidation of porous compacts pressed of aluminum, chromium, andsilicon powder mixtures under air heating and holding in the air at 500 °C has been investigated by quantitative method. It is found that the oxidation exceeds sometimes the oxidation of pore-free materials under the same conditions.Structural studies of oxidized compacts have been carried out by metallographyand X-ray diffraction. The obtained results are discussed with regard for phasetransformations in powder mixtures as well as the factors decreasing the weightof compacts at heating.
Key words: aluminum, chromium, silicon,oxidation, volume changes, phase composition, microstructure.
THEORY AND PROCESSES OF POWDER MATERIAL FORMATION AND SINTERING
Gorbushin A. V., Syrnev B. V., Rusin Yu. G.,Shevchenko G. M.
Study of the effect of speed compactingcharacteristics on thequality of uranium dioxide products
The results of the investigations concerning the effect ofnon-uniformity (discontinuity, step structure) and pellet compaction speed onthe kinematics of uranium dioxide powder sealing and the quality of pellets asto cracks are given. The stress field in the volume of compacts is plotted. Thetendency of uranium dioxide powder compacts to crack formation is shown to beconnected to the instability of speed characteristics and stress state in thepowder volume at non-uniform compaction. It is found that the presence ofdefects as to cracks in uranium dioxide powder pellets with dry adhesive islower than in pellets with liquid one. A mechanism is proposed ensuring theuniform condition of compaction and reducing rejects as to cracks for compactswith liquid and dry adhesives.
Key words: nuclear fuel pellets,formation, presence of defects, adhesive, uranium dioxide, powder, crackformation, speed characteristics, sealing kinematics, stress field, stressstate, non-uniform compaction.
SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS (SHS)
Titova Yu. V., Shiganova L. A., Maidan D. A.,Bichurov G. V.
Self-propagating high-temperature synthesis ofnano-structured aluminum nitride powder with the use of aluminum fluoride and sodium azide
Aluminum nitride nanofibers have been successfully synthesized bydirect reaction of AlF3 with NaN3. The reaction product (gray white powder) has beenexamined by scanning electron microscope. The results show the product havingfibrous morphology with fiber diameter less than 100 nanometers. The effect ofexternal nitrogen gas pressure in the reactor, relative initial charge mixturedensity, and sample diameter on the temperature and burning rate in the AlF3–3NaN3 system isshown. Optimal process conditions of aluminum nitride nanofiber synthesis arefound.
Key words: selfpropagatinghigh-temperature synthesis, aluminum fluoride, sodium azide, burning, aluminumnitride, nanofibers.
REFRACTORY, CERAMIC, AND COMPOSITE MATERIALS
Nozhkina A. V., Yermolaev A. A., Laptev A. I.
Properties of polycrystalline diamond compositematerials (carbonado) synthesized in the Ni–Co–C system
Synthesis and properties of polycrystalline diamond compositematerials (carbonado) produced with application of Ni-Co alloy as catalystshave been studied. Optimal compound of Ni-Co catalyst is alloy containing 60 % Co. It is found that the strength of polycrystalline solids is dependent on the compositionand mechanical properties of binder metal.
Key words: polycrystalline diamond,alloy-catalyst, carbonado, synthesis.
REFRACTORY, CERAMIC, AND COMPOSITE MATERIALS
Kurbatkina E. I., Belov N. A., Gorshenkov M. V.
Structure and phase composition of composite pellet on thebasis of ALTEK heat-resistant aluminum alloy with boron-containing filler
Composite pellets on the basis of ALTEK heat-resistant aluminumalloy (of the Al–Cu–Mn–Zr system) reinforced with B4Cparticles of ~ 11 % in volume portion and 1–10 ?m in size have been produced bymechanical alloying. The structure of pellets shows a great deal of inclusionsof Al15(Fe,Mn)3Si2 phase having globular shape and about 2 ?m inaverage size. It is conjectured that these inclusions, along with B4C, can be considered as reinforcing filler.
Key words: mechanical alloying,radiation protection, ALTEK alloy, heat-resistant aluminum alloy, boroncarbide, phase composition, structure, reinforcing filler.
REFRACTORY, CERAMIC, AND COMPOSITE MATERIALS
Tokova L. V., Zaitsev A. A., Kurbatkina V. V., Levashov E. A., Sidorenko D. A, Andreev V. A.
The features of the effect of nanosized ZrO2 and WСadditives on the metal-matrix composite properties
The effect of ZrO2 and WС nanoparticles on the properties of Fe-based metal-matrix compositehas been studied. The optimum content of nanoparticles and the method of theirintroduction into alloy composition have been experimentally found. The effectof nanoparticles on the compactability of powder material, mechanical andtribological behavior of the alloy has been analyzed. The metal matrixcomposite dispersion-hardened by nanoparticles obtained by hot compactionprocess is characterized by higher hardness and wear resistance.
Key words: ZrO2 and WC nanoparticles, metal-matrix composite,compactability, sinterability, porosity, diamond tool, hardening, cold and hotcompaction.
POROUS MATERIALS AND BIOMATERIALS
Timofeyev A. N.
Calculating and theoretical estimation ofpenetration depth of chemical gas-phase deposition of pyrolytic matrices inporous bodies
A procedure is proposed for calculating the penetration depth ofchemical gas-phase deposition of high-melting-point materials in porous bodiesto select the process parameters for producing pyrolytic-matrix composites. Therelationship between the penetration depth and porous body and gas-phasecharacteristics is presented. The calculated data are shown to allow revealingthe mechanism of processes developed as well as reducing considerably thenumber of experiments to determine the effective process parameters.
Key words: chemical gas-phase depositionin porous body volume, high-temperature composites.
SURFACE MODIFYING, USING CHARGE-PARTICLE BEAMS, PHOTON AND PLASMAFLUXES
Oskolkova T. N., Budovskikh E. A., Goryushkin V.F.
Special features of surface layer structureformation during electroexplosive alloying of tungsten-carbide hard alloy
Hardening of WC + 10 % Co hard alloy surface up to 25000 MPa hasbeen carried out by affecting it with impulse plasma jets formed duringelectric explosion of carbon-graphite fibers, aluminum or titanium foil. It isestablished that the alloys after electro-explosive alloying by titaniumpossess greater hardening at the cost of TiC and (Ti, W)С formation in the surface layer.
Key words: drilling and mining-cuttingtools, WC-Co hard alloys, surface hardening, electro-explosive alloying,carbides.
NANO-STRUCTURED MATERIALS AND FUNCTIONAL COATINGS
Mikhailov I.Yu., Konyukhov Yu. V., Ryzhonkov D. I., Kostitsyn M. A.
Production of molybdenum nanopowders frompetrochemical waste
A technique of molybdenum and molybdenum trioxide nanopowderproduction from petrochemical waste has been developed.Aluminum-cobalt-molybdenum catalysts of GO-70 grade (10 wt.% Mo) were used asinitial material. Initial, intermediate, and final products were examined withX-ray spectrometry, X-ray phase and thermogravimetric analyses, SEM andmeasurement of specific surface. The effect of reduction temperature on dispersionand morphology of molybdenum metal as well as the extreme character of processtemperature dependence of specific surface is determined.
Key words: desulphurization,nanopowders, molybdenum, molybdenum trioxide, metastable ammonium molybdate,thermogravimetric analysis, X-ray analysis, specific surface, dispersion,morphology.
NANO-STRUCTURED MATERIALS AND FUNCTIONAL COATINGS
Tatarinov V. F., Zolkin P. I.
Theoretical estimation of friction coefficientof carbon-nanocomposite thigh joint implant
Carbon nanocomposite (carbon-glass-ceramics) is produced by directedcrystallization in the process of methane pyrolysis under boron tetrachloride.Pyrolytic process of components allows producing material with isotropicfine-grained structure, crystallite sizes of 10–20 nanometers, and highphysicomechanical properties. Nanocomposites have widespread application inmedical articles for cardiology, orthopedics, stomatology, traumatology, etc.Studies of its tribotechnical properties have been carried out. The obtainedresults will be useful in designing medical and other carbon nanocompositearticles.
Key words: carbon nanocomposite,carbon-glass-ceramics, tribotechnics, roughness parameters, frictioncoefficient.
NANO-STRUCTURED MATERIALS AND FUNCTIONAL COATINGS
Zamulaeva E. I., Levashov E. A., Pogozhev Yu.S., Sviridova T. A., Petrzhik M. I., Kudryashov A. E.
Formation of protective coatings on Kh12MF steelby sequential electro-spark machining operation
Coatings on Kh12MF have been produced with consecutive electro-sparkmachining by TiB2–20%NiAl electrode andcarbon-containing materials. Their formation process kinetics, phasecomposition, mechanic and tribological properties, roughness and durability tohigh-temperature oxidation has been studied. In depositing coating by TiB2–20%NiAl electrode, the effect of disproportionalincrement of substrate erosion speed is found, which is observed with increasein unit pulse energy and resulting in boride phase content decrease in thecoating. The consecutive electro-spark machining of boride coating byfine-grained dense graphite electrode resulted in appreciable improvement oftribological properties of coating without affecting its durability tohigh-temperature oxidation. In case of application of siliconized compositeelectrode the durability of coating to high-temperature oxidation considerablyincreases, however the improvement of tribological properties was not observed.
Key words: electro-spark machining,coating, titanium boride, siliconized composite material, fine-grained densegraphite.
APPLICATION OF POWDER MATERIALS AND FUNCTIONAL COATINGS
Krokhalev A. V., Kharlamov V. O., Kuzmin S. V.,Lysak V. I.
Tribotechnical properties of powdered hardalloys of chromium carbide with titanium produced by explosive compaction
Tribological characteristics of the Cr3C2–Ti system hard alloys produced by explosivecompaction of powders containing 20, 30, 40, and 50 vol. % titanium binderhave been examined. Common approach to selection of optimum structure and propertiesof wear-resistant hard alloys for manufacture of journal bearing parts workingtogether with siliconized graphite in the conditions of water lubrication isformulated. It is shown that for reaching the highest antifrictioncharacteristics and minimum deterioration of friction unit, the alloy shouldhave the highest hardness with minimum admissible specific volume of carbidephase in the material structure. It is established that the above alloys havehigher antifriction characteristics and wear-resistance compared withsiliconized graphite and КХН type materials, which areproduced by traditional techniques.
Key words: chromium carbide, titanium,hard alloy, explosive compacting of powders, tribotechnical methods,antifriction material, friction, wear.
