Magazine «Powder Metallurgy and Multifunctional Coatings. News ofHigher School»
Contents V. 2, 2012
POWDERPRODUCING PROCESSES AND PROPERTIES
GostishchevV.V., Dorofeyev S.V.
Metallothermicsynthesis of boride-containing powders of chromium and molybdenum in ionicmelts .
Theconditions of boride-containing chromium and molybdenum powder synthesis havebeen considered in joint reduction of metal oxides and boron compounds in NaCland NaF–NaCl melts at T = 1123?1173 K. The content of boride phases inthe composition of Cr–CrB, Mo–MoB composites is
shownto reach 40–60 wt.%. The specific surfaces of chromium and molybdenum amount to23,38?105
and18,43?105 m–1 respectively.
Keywords: metallothermy, ionic melts, synthesis ofpowders, chromium and molybdenum oxides and borides, thermography, specificsurface, granulometric characteristics.
POWDERPRODUCING PROCESSES AND PROPERTIES
ObabkovV.N., Barakhoev V.V., Obabkov N.V., Zakirov I.F.
Productionof powders on the basis of zirconium dioxide with rod-like shape of particles
Aprocess of producing ZrO2–Y2O3 powders with rod-like shape of particles bysaturation of viscose fabric with zirconyl and yttrium nitrate solutionfollowed by drying and roasting at temperature of 1400 °C and screening. The effect of process parameters (concentration of zirconyl nitrate ininitial solution, saturation time and temperature, and drying temperature) onthe geometrical parameters (height and diameter) of powder particles has beeninvestigated. It is established that viscose fiber diameter and initialsolution concentration affect the diameter of formed particles. The particleheight is determined by the screen cell size, on which screening of viscosefabric is carried out, and the screening number through it. It is establishedthat the powder fluidity increases significantly as a result of frequentscreenings through the screen with cell size of 315 ?m and increase of thesaturating solution concentration. Production of 1 kg of ZrO2–7%Y2O3 powder under the optimal conditions needs about 10 m2 of viscose fabric.
Keywords: production of powders, oxide powders,particle form, fluidity of powders, zirconium dioxide, plasma spraying, viscosefabric, solution impregnation, drying, roasting.
POWDERPRODUCING PROCESSES AND PROPERTIES
OnishchenkoD.V., Reva V.P.
Newaspects of mechanochemical process of titanium carbide synthesis.A pyrolysisprocess of carbon modifications of vegetative raw materials is presented. Theirstructure and degree are limiting factors of the mechanochemical synthesis inthe titan–carbon system.
Keywords: vegetative raw materials, titanium carbide,mechanochemical synthesis, mechanical activation, aromaticity degree, structureof carbon
modifications.
POWDERPRODUCING PROCESSES AND PROPERTIES
AndryushkinA.Yu.
Optimalorganization of dispersion unit with multiple gas supply
Thespraying flame structure in a dispersion unit (DU) with multiple gas supply inusing the supersonic gas dynamic method for production of fine
powdersis considered. Different versions of the DU packaging arrangement with multiplegas supply to the spraying flame are presented. The procedure of optimumarrangement of gas supplying nozzles to the DU is proposed. The results ofstudying the effect of the DU and gas outflow velocity on the dispersivity andform of powder particles are given.
Keywords: supersonic gas-dynamic method, dispersion,spraying.
SELF-PROPAGATINGHIGH-TEMPERATURE SYNTHESIS (SHS)
PogozhevYu. S., Levashov E. A., Kudryashov A. E., Zamulaeva E. I., Novikov A. V., PotaninA. Yu.
CompositeSHS-materials on the basis of titanium carbide and nikelide alloyed byhigh-melting nanocomponent
Thework is devoted to synthesis and investigation of composite ceramic materialson the basis of titanium carbide and nickelide with using the effect ofprecipitation hardening by purposeful alloying of reaction mixture bynanodispersed high-melting component. The effect of nanodispersed
particleson the main combustion parameters under the quasi-isostatic compression isshown. The phase composition and structure of compacted synthesized products inwhich TiC and TixNiy intermetallic compound of nonstoichiometric have beenstudied. It is established that alloying by a nanocomponent does not varyqualitatively the phase composition; however this results in essentialmodification of the material structure where the average grain size of the mainhigh-melting component decreases 1,5–3,5 times. Moreover, the similar effect isobserved in reducing TiC concen-
trationin the sample concentration. Complex investigations of physical-mechanicalproperties and heat-resistance of produced materials have been carried out. Theeffect of positive effect of high-melting nanoparticles for suchcharacteristics of alloys as hardness, strength, Young’s modulus, high-
temperatureoxidation resistance is shown.
Keywords: self-propagating high-temperature synthesis,composite materials, dispersion-hardened materials, nanoparticles,intermetallic compounds.
REFRACTORY,CERAMIC, AND COMPOSITE MATERIALS
OrdanianS. S., Zarichnyak Yu. P., Balnova E. S.
Onabnormality of concentrating dependences of thermal conductivity of ceramics
inthe TiN–AlN, ZrC–ZrB2 systems with structure of «rough conglomerate eutectics»
Experimentallyfound abnormal kind of the concentration dependence of binary-ceramic-compositethermal conductivity is explained in physi-
calterms. A model of the structure and computing (forecasting) method of «eutecticmodels» group composite thermal conductivity are proposed.
Keywords: nanodispersed composite materials, ZrC-ZrB2and TiN–AlN binary ceramic eutectics, abnormality of concentration dependenceof thermal
conductivity,model of ceramic composite structure, computing method of anomalousconcentration dependence of effective thermal conductivity.
POROUS MATERIALSAND BIOMATERIALS
FedotovA. F.
Plasticitycondition for porous sintered materials taking account of local character ofstrengthening phase deformation
Theplasticity condition for porous sintered materials is proposed in view of nonhomogeneouscharacter of plastic deformation of solid phase. In this case, the hypothesison formation of deformable/nondeformable volumes in it is accepted, and thestrain resistance is geared only to the first of them. The calculation ofdeformable volume should be carried out with taking the initial powderedcondition of sintered material and its bulk density into account. The proposedplasticity condition shows a good conformity of computed and experimental datafor various deformation schemes of porous sintered materials for which theyield strengths and laws of strain hardening of corresponding cast materialsare used. The methodology of compu ting-experimental researches and thenecessary conditions of adequate description of elastic and plastic propertiesof compacted and sintered powdered materials are considered.
Keywords: porous sintered material, plasticitycondition, deformable volume, strain hardening.
NANO-STRUCTUREDMATERIALS AND FUNCTIONAL COATINGS
BetsofenS. Ya., Borisov A. M., Vladimirov B. V., Vostrikov V. G., Romanovsky E. A.,
SavushkinaS. V., Sorokin V. A., Tkachenko N. V., Frantsevich V. P., Epelfeld A. V.
Productionof nanocomposite ceramic coatings on zirconium alloy by microarc oxidation
Theresults of studying the structure and composition of nanocomposite ceramiccoatings applied onto E110 zirconium alloy by microarc oxidation method (MOM)with addition of yttrium and aluminum oxide nanopowders are given. Theinvestigations have been carried out by dint of
scanningelectron microscopy, X-ray microprobe analysis, nuclear back scatteringspectrometry, and X-ray structure analysis. High-temperature zirconium oxidephases are identified in the MOM-coating upon introducing yttrium oxidenanopowder in quantity of 7 g/l into the electrolyte
of 2 g/l КОН + 6 g/l NaAlO2 + 2 g/l Na2SiO3 composition. Additives of 5 g/laluminum oxide into the electrolyte containing 2 g/l KOH resulted insignificant increase of coating porosity.
Keywords: microarc oxidation, nanocomposite ceramiccoating, nanopowder, yttrium oxide, aluminum oxide.
NANO-STRUCTUREDMATERIALS AND FUNCTIONAL COATINGS
SheveikoA. N., Kiryukhantsev-Korneev F. V., Kutyryov A. E., Shtansky D. V.
Electrochemicalbehavior of multicomponent bioactive nanostructural coatings on the basis oftitanium carbonitride
Forincreasing biointegration of titanium implants, hard bioactive nanostructuralcoatings on the basis of titanium carbonitride alloyed by phosphorus, calcium,tantalum, and silicon have been proposed and received practical approval. Theireffect on electrochemical properties of the coatings in
thebiological standardized test solution is considered. All the coatings are shownto be in stable passive condition, and alloying does not worsen essentiallytheir electrochemical properties. An example of coating vacuum-depositionparameter optimization for the purpose of improvement of its
electrochemicalcharacteristics is considered for one of the compositions.
Keywords: bioactive nanostructural coatings, magnetronsputtering, structure and composition, free corrosion potential, anodebehavior, cyclovoltammetry.
NANO-STRUCTUREDMATERIALS AND FUNCTIONAL COATINGS
YankovskyA. P.
Theeffect of thermal action on strengthening of plates with thin hard coatings
Basedon general representations of the linear theory of unbound thermoelasticbehavior the problems of calculation of temperature fields and mechanicalbehavior of ring plates with hardening coverings are formulated. The jointnumerical method of thermal conductivity and thermoelasticity problemintegration has been developed and concrete calculations have been carried out.It is found that in availability of certain types of tempera-
turefields in a plate, the effect of sharp reinforcement cannot be become apparentin applying thin (0,1–0,8 mm) high-modulus coatings on its surface, beingobserved, for example, in the natural operational conditions when thermalaffect is lacking.
Keywords: coated plates, rigid coatings, hardeningeffect, softening effect, unbound thermoelasticity, thermal affect.
NANO-STRUCTUREDMATERIALS AND FUNCTIONAL COATINGS
PanovV. S., Shumenko V. N.
Siliconnitride coating on carbide cutting tools
Thedata for properties and structure of silicon nitride coating on carbidematerial are given. The data are verified by X-ray crystal, spectrographic, and
differentialthermal analyses as well as electron-microscopic results of investigation. Theexamined properties render possible to make a conclusion
onthe opportunity to use carbon nitride as wear-resistance coating material oncarbide cutting tools.
Keywords: carbide material, Si3N4 coating, structure, properties.
