The following types of metal-base nanopowdersare very commonly used:· Aluminium oxide nanopowders. The synthesized productis a highly porous white powder with the bulk density0.6∼0.7 g/cm3 and specific surface ∼20 m2/g. The shapeFig. 6. A potential structure of a nanotube circuit [6]. 6 A.G. Mamalis / Journal of Materials Processing Technology 161 (2005) 1–9 of Al2O3 particles is predominantly spherical, with an av-erage particle size varying from 30 up to 300 nm, depend- on their basis can be utilized as a basic material or as themodifying additives at manufacturing of: ······· ing on the synthesis conditions.Magnesium oxide whiskers. The synthesized product is ahighly porous white powder. Its particles mainly have ashape of the whisker with an average diameter of ∼60 nmand a relation of whisker’s length to its diameter about100. The synthesized particles can be covered with a thin(∼10 nm) solid layer of carbon during the synthesis pro-cess.Zirconium dioxide nanopowders. The synthesized productis the highly porous white powder white light yellow shade.Zirconium dioxide ZrO2 + 6% Y2O3, with an average sizeof particles ∼200 nm may be synthesized, with the synthe-sized powder stabilized in equilibrium tetragonal modifi-cation.Zirconium dioxide ZrO2 + 6% Y2O3, with an average sizeof particles ∼30 nm is also formed. The particles form “fri-able” conglomerates by the size up to 500 nm, whilst thestabilization of high temperature oxide cubic modificationis caused by the small size of particles and additives ofyttrium oxide.Zirconium dioxide ZrO2, with a characteristic particle size∼5 nm. The powder has cubic modification, the stabiliza-tion of which is determined by the small size of particles.Mixtures of nanopowders. There is an opportunity of pro-ducing the mixtures of the listed above powder’s assort-ment during the synthesis process. The obtained powderyproducts are characterized by the uniformity of compo-nents allocation in the mixture. The formula can be con-trolled and set at a stage of initial component preparation.The synthesized nanopowders were utilized for modify-ing wolframic and non-wolframic hard facing alloys. Thepositive changes in material structure allow for increas-ing wear resistance by 150–200%, fracture toughness by50%, stability resistance at metals treatment by cuttingby 150–200%. The electro-technical pseudo-alloys, rein-forced by synthesized nanoparticles of ZnO meet the re-quirements of the technical specifications for metal ceram-ics contact.Nanopowders of metal oxides and carbides may also con-sist another group of mixtures. Turbostratum graphitewith interplanar distance 3, 42 A˚ may also form mix-tures with metals like Ti, Mg, Zr burns and the metal car-bides are forming by self-propagating high-temperaturesynthesis (SHS). At synthesis of titanium carbide with tur-bostratum graphite the burning rate has increased morethan twice in comparison with burning rates of tita-nium mixture with synthetic graphite and different carbonsoot. · sintered powdery ceramics, hard-a1loy and ceramic com-posites;· nanoparticles reinforced metal and polymeric matrix com-posite;· abrasive pastes and suspensions and polishing ones;· chemical catalysts and sorbents.Crushing of the brittle materials grains can be achievedby shock loading. These phenomena are used for producingnanoscale materials of micro- and macroscale grains. By ap-plying properly calculated and directed shock waves createdby explosion Al2O3, MgO, ZrO2, Mo, Ti, W and ceramicsuperconductors with the composition of YBa2Cu3O7−x. aretreated for reducing their grain size into nanoscale.Compaction of nanomaterials by shock waves has he ad-vantage that during the compaction phase grain growth doesnot occur. The high-speed shock waves with high energycontent can be created either by initiating high explosives(explosive compaction) or by discharging electric capacitors(electrodynamic compaction), see Ref. [2].4. Processing of high-Tc superconductors4.1. Fabrication of metal-sheathed YBCO and BSCCOpartsHigh temperature superconducting materials are fabri-cated by various physico-chemical techniques (solid-state re-action, sol–gel, etc.) in the form of powders. A method thatcan produce monoliths from powders without changing theirunique properties would be very desirable. High-energy ratepowder compaction techniques, e.g. explosive and electro-magnetic compaction, may be considered as tool to producesuperconductive ceramics with unique properties. Shock con-solidation of powders is one-stage densification/bonding pro-cess that presents potential for the above-mentioned specialand difficult-to-consolidate materials. The shock waves orig-inated from explosive detonation and propagated through theporous media, can create high shock pressures and high tem-peratures that result in fracturing the original grains and insintering. The compacted solid contains a variety of primarilyline defects that would provide flux pinning centers in TypeII superconductors.Several industrial applications of bulk superconductingceramics of the YBCO and BSCCO compounds have beendeveloped by the author and his collaborators, using explo-sive and electromagnetic dynamic compaction techniquesand subsequent net-shape manufacturing processes.
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