Self-propagating high-temperature synthesis
Shulpekov A.M., Lyamina G.V., Kalianova T.V., Lepakova O.K., Maksimov Yu.M.
Electrically conductive coatings on the basis of heat-resistant titanium compounds produced by SHS
Titanium carbide, silicide, and carbosilicide have been produced with self-propagating high-temperature synthesis. Microstructure, phase composition, and properties of these compounds are given. The materials as powders have been used for production of conducting polymeric compounds. The effect of filling material type and composition, heat-treatment temperature, resin bond composition on electrical resistance of composite coatings has been investigated. It has been found PFMP ans PFG polymers to be bonding adhesive to provide for the lowest compound resistance with titanium carbosilicide as filling material. The operating temperature of compounds containing PFMP and PFG polymers as filling material shall not exceed 250 °С, 150 °С for SKTN grade, and 300 °С for the mixture of epoxy resin and PFMP ans PFG polymers.
Key words: self-propagating high-temperature synthesis, titanium carbide, titanium silicide, titanium carbosilicide, nanolaminate, polysiloxane, polymeric compound, conductance, film electrical heater, electrically conductive coatings, contact electrical resistance.
High-melting, ceramic, and composite materials
Putintseva M.N., Bashurov Yu.P.
Phase transformations in WC–Co powder annealing
Phase transformations in annealing the powders produced by electrodispersion of WC-Co alloys have been considered. All the powders contained the various amount of high-temperature β-WC phase. Eutectoid decomposition of β-WC→-WC+W2C is found to result first in formation of acicular α-WC crystals and then in their destruction because of their gliding.
Key words: phase transformations, WC-Co powder annealing, electrodispersion, high-temperature WC phase, eutectoid decomposition, needle-shaped twin crystals, crystal gliding, center of crystallization, interfacial angle, peritectoid decomposition.
Vikhman S.V., Klimova O.G., Ordanian S.S., Tolochko O.V., Cheong D.-I.
Activated sintering of W–HfC composite materials
The features of particle consolidation during activated sintering of tungsten powders of various dispersiveness (dav = 2?3 and 0,8?1,0 µm) have been studied. The activation of the sintering process was carried out by introducing nickel additives (as many as 0,5 mas.%), tungsten nanoparticles (as many as 30 mas.%), and fine hafnium carbide (5–30 vol.%) followed by vibrating mill grinding. Uniaxial compaction of the specimens was implemented at pressure from 50 to 1000 MPa, and sintering was performed in vacuum at temperature of 1850 °С for 1 h. Tungsten nanoparticle additives are shown to build up sintered bar density, and in combination with dispersed hafnium carbide one may produce tungsten based composite materials with grain size as small as 2 µm.
Key words: tungsten, tungsten powders, hafnium carbide, mechanical activation, uniaxial compaction, activated sintering, density, porosity.
Aleutdinova M.I., Fadin V.V.
Effect of electric current to destroy the friction surface of sintered metal composite
Wearing capacity and electrical resistance of a friction zone of powder simulative composites based on Gadfield steel (13 % Mn) and processed ShKh15 steel have been determined under the conditions of sliding electric contact at current density more than 100 A/cm2. The material structure and three-dimensional image of the friction surface are given. It is shown that Gadfield steel based composite forms the contact zone having high electrical resistance and high roughness. In was found that transfer of composite material to steel counterbody surface takes place under the effect of spark-erosion in the friction zone. It has been established that the catastrophic wear conditions are realized at current density about 200 A/cm2. It has been establish ed that the catastrophic wear regime is realized at ~ 200 A/cm2 in current density.
Key words: sintered composite, collector material, sliding electric contact, wear, transfer layer, friction surface.
Panteleev I.B., Lukashova T.V., Ordanian S.S.
Heat-resistance and high-temperature resistance of alloyed WC–Cо–Ni–Re(Mn) hard alloys
Hard metal (HM) oxidation regularities have been established in the "tungsten carbide – metallic bond on the basis of cobalt, nickel, rhenium, and manganese" system. Introduction of Ni–Re or Ni–Mn into cobalt bonding material is found to raise the initial active oxidation temperature by 20–70 °С and decreases its rate in the following order: Co–Ni, Co–Mn → (Co–Ni–Mn, Co–Re, Co–Ni) → Co–Ni–Re → Ni–Re. The mode of temperature dependence of strength in HM bending with Co–Ni and Ni–Mn bonding materials is no different from those for VK type alloy, and Re addition into the bonding material drastically changes this. Certain HM hardening (below 20 %) takes place below 600 °С for Ni–Re bond and 800 °С for Co–Re bond, and then their strength decreases but remains higher than for materials with cobalt and nickel bonds. Maximum HM strength of the WC–Co–Ni–Re system can be reached in a range of t = 600?800 °С, corresponding to the cutting edge temperature.
Key words: hard material, heat resistance, high-temperature strength, tungsten carbide, bonding metal, oxidation, cobalt, nickel, rhenium, manganese.
Surface modifying including by charged particle beams and photon and plasma fluxes
Demidenko V.V., Potyomkin G.V., Starostin G.T., Oskin Yu.V., Revin P.E.
Plant of vacuum-arc processing of structural material surface
A pilot plant has been designed for metal and alloy surface processing by vacuum-arc discharge for preparation of technological process to apply protective coatings on parts made of structural materials. Design and performance data of the plant are given. A prototype of the arc evaporator with arch magnetic field functioning at nitrogen pressure of 10–1000 Pa in the chamber, arc currents 20–250 A, and long arc volts up to 50 V is developed. The properties of near-surface layer of steel sheet after its processing and storing under increased humidity for several years are shown not to vary.
Key words: modification, cleaning and activation of structural steel surface, construction and performance data of unit, processing efficiency.
Ovchinnikov V.V., Remnev G.E., Gushchina N.V., Guselnikov V.I., Mozharovsky S.M., Filippov A.V., Kaigorodova L.I.
Changes in microstructure of cold-worked 1441 aluminum-lithium alloy, which are initiated by powerful pulsed ion beams
The paper presents the results of electron-microscopic investigation of 1441 alloy of the Al–Сu–Мg–Li–Zr–Мn system after cold rolling (ε = 72 %) and subsequent irradiation with powerful pulsed ion beam (70 % C+ + 30 % H+) in pulse-periodic mode (τ = 80 ns, f = 0,1 Hz) and in the mode of single pulse generation only (τ = 180 ns). The ion energy was 180 keV. Using the transmission electron microscopy, irradiation of cold-worked 1441 alloy to low exposures of 1·1014–2·1015 cm–2 was shown to cause the noticeable transformation of the cellular dislocation structure formed in it. It was found that increase of pulsed ion current density results in increase of the intensity of structural changes in the alloy.
Key words: modification of surface with particle beams, radiation-dynamic effect of accelerated ions, powerful pulsed ion beams, aluminum alloys, cold work, transmission electron microscopy, microstructure, dislocation structure transformation.
Nano-structured materials and functional coatings
Kiryukhantsev-Korneev F.V., Sheveiko A.N., Komarov V.A., Blanter M.S., Skrylyova E.A., Shirmanov N.A., Levashov E.A., Shtansky D.V.
Nanostructural Ti–Cr–B–N and Ti–Cr–Si–C–N coatings for carbide cutting tools
Nanostructured Ti–Cr–B–N and Ti–Cr–Si–C–N coatings with different chromium and nitrogen content have been produced by magnetron sputtering of composite multiphase targets. Their structure and phase composition have been studied by X-ray diffraction, TEM and SEM, XPS and glow-discharge optical emission spectroscopy. FCC-phase with (100) texture and < 25 nm in crystallite dimension is the base of Ti–Cr–B–N and Ti–Cr–Si–C–N coatings. Si3N4 based hexagonal phase was also found in Ti–Cr–Si–C–N coatings. The results of studies with the use of nanoindentation, scratch-testing as well as tribological tests show that they have hardness as many as 30 GPa, adhesive strength no less than 35 N, and friction coefficient in a range of 0,35–0,57. In addition, the coatings have high thermal stability, oxidation resistance, and corrosion resistance in 1N solution of H2SO4. The data obtained in testing carbide cutting tools are indicative of the nanostructural Ti–Cr–B–N and Ti–Cr–Si–C–N coatings, which raise the tool resistance 11–17 times.
Key words: nanostructured coatings, magnetron sputtering, SHS-targets, hardness, friction coefficient, wear resistance, corrosion resistance, thermal stability and oxidation resistance, coated cutting tool.
Popov V.A., Zaitsev V.A., Prosviryakov A.S., Samoshina M.E., Sagalova T.B., Khodos I.I., Kovalchuk M.N.
Study of mechanical alloying processes in producing composite materials with nanosized strengthening particles
The research work is devoted to studying the processes of producing metal-matrix composites with powdered nanodiamond strengthening particles. The following diagram was used for researches: mechanical alloying of starting components in planetary mills to produce composite material granules and subsequent compaction of produced granules in bulk material. Copper and brass powder mixture has been processed in the planetary mill to study the mechanical alloying processes. The difference in color of components allowed studying the processes of mixing components. It is established that insufficient processing time results in strengthening particle agglomeration on the granule surface, thus leading to decrease of the mechanical characteristics. In case of uniform distribution of strengthening particles in the matrix, high level of the properties of composite materials can be reached.
Key words: metal-matrix composites, mechanical alloying, nanodiamonds, strengthening particles.
Process and material quality control
Kem A.Yu.
Development of environmentally determined processes to produce articles from aluminum powders with powder metallurgy techniques
For the purpose of ecologically safe realization of aluminum powder metallurgy processes it is necessary to develop high-efficiency technologies based on partly or completely closed cycles and new techniques of preparation of initial fine powders that lower their dust-forming ability and settling the problem of explosion and fire hazardous production.
Key words: simulation, ecological properties, aluminum powders, decomposition, Isikawa diagram, Pareto curve, АВС-analysis, ranging.
