• MATERIALS

    MICROSTRUCTURE AND MECHANICAL PROPERTIES OF A HYPEREUTECTIC ALLOY AlSi18, MODIFIED BY A NANODIAMOND AND PHOSPHORUS

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 11, pg(s) 504-506

    A study of a hypereutectic aluminum-silicon alloy AlSi18, modified by a conventional modifier – phosphorus (P) and a nanosized powder of a nanodiamond (ND) has been carried out. Refinement by 40.8% of the primary Si crystals and by 51% of the Si crystals in the composition of the eutectic has been obtained for the phosphorus-modified alloy in result of the modification. The refinement of the above values for the alloy modified by ND is 41.5% and 94% respectively. The phosphorus-modified alloy AlSi18 has an increased tensile strength (Rm) by 18.5%, relative elongation (А5) by 14.3% and hardness by 1.5%. The alloy, modiified by ND has an increased by 20.4% tensile strength (Rm), increased relative elongation (А5) by 7.15% and hardness decreases by 6.2%.

  • Modifying of aluminum alloy AlSi7Mg with nanocompositions

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 4 (2018), Issue 4, pg(s) 114-117

    A methodology was developed for the casting of samples of AlSi7Mg alloy modified with nanocomposites (NCs). The following NCs were used: SiC + Cu, AlN + Cu + Al, TiN + Cu, SiC + Al, SiC + Ag Cu, where Ag and Al are cladding metals. The introduction of the nanocompositions takes place in the crucible of a furnace. A thin-walled cylindrical casting mould is used on whose axis is installed a protected thermocouple to measure temperature variation as a function of time. The effect of NCs on overcooling and on sample structure is established.

  • PERSPECTIVE COMPOSITE MATERIALS FOR GENERAL AND SPECIAL MECHANICAL ENGINEERING

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 6, pg(s) 258-259

    The work considers the use of carbon nanotubes to enhance the functional characteristics of polymer materials. The results on studies of the electrophysical properties of polymers doped with carbon nanotubes are presented and prospects for the use of such materials are discussed.

  • MATERIALS

    EFFECT OF POWDER MODIFIERS ON STRUCTURE FORMATION OF IRON-CARBON ALLOYS

    Machines. Technologies. Materials., Vol. 11 (2017), Issue 7, pg(s) 370-372

    Effective modification not by expensive nano-powders but by relatively large ones (up to several microns) and capable to dissolve when entering into the melt and become additional crystallization centers at its start point was shown. That provides a metal structure refinement and, consequently, increases the whole complex of mechanical properties. The optimal process parameters of refractory compounds disperse powders modification were proposed.

  • INFLUENCE OF NANOSIZED SILICON NITRIDE ADDITION DURING CASTING ON THE MICROSTRUCTURE OF X210Cr12 STEEL

    Machines. Technologies. Materials., Vol. 8 (2014), Issue 1, pg(s) 35-10

    The objective of this study is to investigate the effect of modification and nitrogen alloying of X210Cr12 tool steel by addition of nanosized Si N during the casting process. This is an air hardening, high-carbon, high-chromium tool steel which displays an excellent 3 4 wear resistance and has good dimensional stability and high compressive strength. Of great importance for the tools fabrication of this steel is the ledeboritic structure after casting and the influence of its characteristics on the next processes of forging. machining and heat treatment for obtaining of optimal properties. In this case a modification at the cast process and obtaining of finer structure is a precondition for better results on the next stages of tool manufacture. The role of nitrogen for obtaining of fine grained structure is already proved for many types of steels and the alloying process is precise developed. Si N is one of the most suitable nitrogenous alloying agents 3 4 for production of alloyed with nitrogen steels because of its high nitrogen content and stability. The investigations show a considerable improvement of the cast structure of X210Cr12 tool steel after the addition of small amount of nanosized silicon nitride during the casting process.

  • TECHNOLOGY LASER MODIFICATION IN MATERIAL SCIENCE NANOCOMPOSITES FOR METAL-POLYMERIC SYSTEMS

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 2 (2016), Issue 3, pg(s) 8-9

    Are investigated mechanisms and kinetics of structural transformations polymeric substrates and of disperse particles fillers and modifiers exposed defocused laser radiation with energy in the range of 1.5 to 6 J. Installed effect of hardening the thermoplastic matrices (polyolefins, polyamides, of polyesters) when exposed to short laser pulses on a film sample thicknesses of 50-200 microns. The methods of structural analysis (IR spectroscopy, X-ray diffraction, DTA) showed, that the predominant mechanism of manifestation hardening effect is the formation of nano-sized structures in the film sample volume due to leakage of recrystallization processes. When exposed to laser radiation to disperse and fibrous particles of silicates, graphite, schungite, carbon fibers is implementing a complex effect of increasing the dispersion and the formation of advanced morphology of the surface layer with an increase in the proportion of nano-sized fragments whisker and lamellar habitus. When laser irradiation of fibers fragments formed developed morphology of the surface layer, due to the occurrence of thermal degradation processes that lead to the appearance of cracks and of globular indentations. Spectroscopy method of thermally stimulated currents (TSC – spectroscopy) established the effect of changing the energy state of the surface layers of substrates and particulate modifiers, which are characterized by extreme values of magnitude TSC – currents in the temperature range 193-523 K. The combined effect of energy and morphological factors provides the effect of increasing the activity of modifying components subjected to the laser processing. Changing the energy state of the surface layer of the polymer substrate has a beneficial bactericidal effect, increases the effectiveness of antiseptic treatment of medical devices used in medical practice. Are presented examples of the practical use of the established laws when creating polymer composites for metal-polymer systems for various applications.

  • NANOCOMPOSITE ENGINEERING MATERIALS BASED ON RECYCLED THERMOPLASTICS

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 1 (2015), Issue 2, pg(s) 13-16

    There were studied features of the structure of composite materials on the basis of recycled thermoplastic (HDPE, LDPE, PP) modified by components of different composition and dispersion. It was established the hardening effect of the matrix of the composite with the introduction of the highly oriented fragments that preserve the structure after the completion of the technological cycle of manufacturing products by injection molding or extrusion. It was proposed the technology of thermo-mechanical combining of thermoplastic components while simultaneous modifying by components of different composition and structure. When modification of fluorinated nanoparticles ablation products is provided the effect of increasing the rate of extrusion and formation of hydrophobized surface layer of products. Nanoscale silicate modifiers (clay, tripoli, metals phosphates and oxides,) contribute to the thermodynamic compatibility of the matrix and the modifier polymer due to formation of a spatial network of physical binds in the volume of the composite. The obtaining technologies for products based on recycled composites that the parameters of deformation strength and tribological characteristics are not inferior to raw materials, but have a significantly lower cost of production.