Institute of Metal Science

Sofia, Bulgaria

Institute of Metal Science

Sofia, Bulgaria
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Kuzmanov P.,Institute of Metal Science | Dimitrova R.,Institute of Metal Science | Lazarova R.,Institute of Metal Science | Cherepanov A.,RAS Institute of Theoretical and Applied Mechanics | And 4 more authors.
Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems | Year: 2014

The influence of nanopowders on the structure and mechanical properties was investigated in castings of aluminium alloy AlSi7Mg, grey cast irons GG15 and GG25 and steel GX120Mn12. Mixtures of SiC, TiCN and Y2O3 nanopowders were used. These mixtures or nanocompositions were coated with Cu, Cr, Ni and Fe metal protectors in order to improve wetting of the metal melt. Introducing small amounts of nanocompositions (less than 0.1 wt%) into the melt was found to refine the microstructure and improve the mechanical properties of the castings. © IMechE 2013.

Bilgili E.Z.,Genel | Salamci E.,Gazi University | Asan A.,Hitit University | Unal R.,Gazi University | Valov R.,Institute of Metal Science
Journal of the Faculty of Engineering and Architecture of Gazi University | Year: 2016

In this study, 0.2% and %0.5 carbon added Distaloy powders produced by utilizing water atomization methodology were pressed under 420MPa compression by an uniaxial press and sintered at 1120°C for 30 minutes. The specimens produced were coated with diamond nanoparticle added chromium using electrochemical method. The coated and uncoated specimens were compared and the effect of coating on the hardness and corrosion behaviour of the powder metal specimens was studied. The specimens were examined with optical microscope and scanning electron microscope (SEM), their X-ray Diffraction (XRD) analysis was made and density were measured as well as they were tested in terms of hardness and corrosion. Their corrosion behavior was studied in 0.1 M NaCl solution by applying Tafel extrapolation method. The experimental results showed that coating of powder specimens with diamond nanoparticles added chromium improves hardness and the corrosion resistance of the samples.

Sobczak J.J.,Poland Foundry Research Institute | Drenchev L.B.,Institute of Metal Science | Sobczak N.,Poland Foundry Research Institute | Asthana R.,University of Wisconsin - Stout
Materials Science Forum | Year: 2013

This paper discusses some theoretical aspects of design of ultralight metallic materials using analytical and heuristic arguments. Potential application of syntactic foams to obtain metalmatrix composites lighter than air is also analyzed. Carbon allotropes (fullerenes, colossal carbon tubes) and some non-carbon materials are considered as components of ultralight metal-matrix composites. Calculations for the size of fullerenes, number of atoms in their structure, and coating thickness required to produce ultralight composites are presented. It is concluded that 3D carbon molecules (fullerenes) and colossal carbon tubes are the most promising components to design ultralight metallic materials which can be lighter than air. © (2013) Trans Tech Publications, Switzerland.

Gidikova N.,Institute of Metal Science | Cias A.,AGH University of Science and Technology | Petkov V.,Institute of Metal Science | Madej M.,AGH University of Science and Technology | And 2 more authors.
Archives of Metallurgy and Materials | Year: 2014

Electrochemical chromium coatings on steel, modified with diamond nanoparticles (NDDS), were produced by detonation synthesis. Their particle size was from 10 to 50 nm. Galvanization conditions, current density, etc., concentration of NDDS, were studied in relation to the characteristics of the chromium coatings. The optimal conditions were determined to attain the maximal values of the physical and mechanical properties of the coating. Surface topography after wear testing was examined. Compared to unmodified chromium coating, microhardness of the surface increased to 1100 kg/mm2, wear resistance, expressed as % of mass loss, increased from 3 to 10 times. © 2014, Committee of Metallurgy. All rights reserved.

Sobczak J.J.,Poland Foundry Research Institute | Drenchev L.,Institute of Metal Science | Asthana R.,University of Wisconsin - Stout
International Journal of Cast Metals Research | Year: 2012

The effect of pressure on solidification structure formation in metal castings has been reviewed and explicitly expressed by thermodynamic relationships. In particular, pressure effects on phase diagrams, nucleation and growth, interfacial energy and diffusion coefficient are considered and analysed. Well known formulae and some new explicit relations are presented and discussed. Practical manifestations of the effect of pressure in casting structure formation are discussed. © 2012 W. S. Maney & Son Ltd.

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