Showing papers by "Igor Yadroitsev published in 2012"

Factor analysis of selective laser melting process parameters and geometrical characteristics of synthesized single tracks

Abstract: Purpose – Properties of the parts manufactured by selective laser melting (SLM) depend strongly on the each single laser‐melted track and each single layer, as well as the strength of the connections between them. The purpose of this paper to establish links between the principal SLM parameters (laser power density, scanning speed, layer thickness), properties of the powder and geometrical characteristics of single tracks. This study will provide a theoretical and technical basis for production of parts from metal powders.Design/methodology/approach – This paper discusses the SLM parameters affecting on geometrical characteristics of the synthesized single tracks. Granulomorphometric characteristics of powders were studied in detail. A Greco‐Latin square design was used to control geometrical characteristics of the tracks. Analysis of variance (ANOVA) permitted to establish a statistically significant influence of the SLM process parameters on geometry of the single laser‐melted track.Findings – The behav...

A new combined approach to metal-ceramic implants with controllable surface topography, chemistry, blind porosity, and wettability

Abstract: The present work focuses on the surface modification of Ti alloys using a combination of various techniques such as cold spray (CS), selective laser sintering (SLS), pulsed electro-erosion treatment (PEET), and magnetron sputtering to control surface topography (roughness and blind porosity), surface chemistry, and wettability, i.e. the characteristics which affect osseointegration. The sample structure, elemental composition, surface topography, and wettability were studied using X-ray diffraction, optical and scanning electron microscopy, glow discharge optical emission spectroscopy, energy dispersive spectroscopy, and water contact angle measurements. The obtained results show that Ti coatings deposited by CS can be divided into three groups with a characteristic value of average roughness R a : (i) 4 μm (single particles and agglomerates on the surface), (ii) 22 μm (thin coatings), and (iii) 80 μm (thick coatings). PEET with pulse discharge energies of 0.025 and 0.38 J resulted in the average values of surface roughness of 3 and 8 μm, respectively. During SLS, Ti powder paths were sintered by a laser beam in mutually perpendicular directions to form surface network structures. By varying the distance between the tracks, samples with blind porosity 1.0–5.1 × 10 − 3 mm 3 were obtained. In order to modify the surface chemistry, multifunctional bioactive nanostructured TiCaPCON films, 1–2 μm thick, were deposited atop the CS, PEET, and SLS samples by sputtering a composite TiC 0.5 + Ca 3 (PO 4 ) 2 target. The wettability measurements showed that the CS and PEET modified surfaces exhibit high values of water contact angle. Ion etching in vacuum and TiCaPCON film deposition made the samples highly hydrophilic. The influence of the surface chemistry and surface topography on adhesion, proliferation, and early stages of osteoblasts differentiation was studied. The combination of high surface roughness and blind porosity with hydrophilicity and biocompatibility makes the fabricated metal-ceramic materials promising candidates for applications involving tissue regeneration.

Peculiar features of electrical resistivity and phase structure in 3-D porous nitinol after selective laser sintering/melting process:

Abstract: The main goal of this study is the peculiarities of shape memory effect in a porous nickel–titanium (NiTi intermetallic phase referred to as nitinol) fabricated via the selective laser sintering/me...

Laser-induced reaction of Si powder with a steel substrate

Abstract: We have determined the phase composition and microhardness of coatings produced by the laser melting of silicon powder on the surface of steel substrates. Laser exposure leads to the formation of iron silicides on the substrate surface. The iron content of the silicides depends on the effective laser power and increases from that of FeSi2 to Fe0.9Si0.1. The coatings have the highest microhardness at an effective power of ≏ 400 W s/m, which corresponds to the highest FeSi content.