Laser-Assisted 3D Printing of Functional Graded Structures from Polymer Covered Nanocomposites: A Self-Review

As a method for conservation of nanoparticles with perspective properties, the three-dimensional (3D) printing is a promising technique for modeling, fabricating of functional graded structures (FGS) with nanoadditives and functional devices. The stabilization of nanoparticles in a polymeric matrix and additionally reinforced porous structure makes it possible to arrange a desired distribution of the nanoparticles in the polymer and thus to protect them from oxidation and corrosion and even to design not only the FGS but also micro/nanoelectromechanical systems (M/NEMS) devices. The synthesized nanocomposites with controlled porosity and large-specific surface may also find their application in implantation, catalysis, lab-on-chips, drug delivery systems, and 3D crystalline structures for hydrogen storage devices

Comparison of Additive Technologies for Gradient Aerospace Part Fabrication from Nickel-Based Superalloys

In our papers, the laser beam-aided control of the self-propagating high-temperature synthesis in Ni–Al systems for the layerwise manufacture of three-dimensional (3D) parts was offered and experimentally realized. As for the laser in situ synthesis of NiAl and Ni3Al intermetallides and their layerwise laser cladding without any visible cracks and pores, it was successfully performed later on. The present chapter is dedicated to the comparison of optimal conditions for the selective laser melting and laser direct metal deposition processes of the nickel-based powders and fabrication of a full-density, functionally graded, and crack-free structures on the maximum deposition rate for technological applications. The effects of laser parameters on the phase composition and microstructure of the resulting intermetallic samples will be discussed

Layer-by-layer laser synthesis of Cu–Al–Ni intermetallic compounds and shape memory effect

Published ArticleWe have studied conditions for the synthesis of intermetallic phases in the Cu–Al–Ni system by selective laser sintering/melting, in particular by heating a powder mixture to 300°C. The effects of laser synthesis and heating on the microstructure of the intermetallic phases in the samples obtained have been studied using electron microscopy, optical metallography, and X-ray diffraction analysis. The results demonstrate high sinterability of stoichiometric mixtures. Resistivity measurements indicate that the samples exhibit a shape memory effect. We discuss the feasibility of producing biomicroelectromechanical systems using layerby- layer synthesis

2FGL J0846.0+2820: A new neutron star binary with a giant secondary and variable γ\gamma-ray emission

We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated \emph{Fermi}-Large Area Telescope (LAT) $\gamma$-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric ($e$ = 0.06) 8.133 day orbit with an invisible primary. Modeling the spectroscopy and photometry together lead us to infer a heavy neutron star primary of $\sim 2 M_{\odot}$ and a partially stripped giant secondary of $\sim 0.8 M_{\odot}$. H$\alpha$ emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find the $\gamma$-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then it has not been detected by \emph{Fermi}. The long period and giant secondary are reminiscent of the $\gamma$-ray bright binary 1FGL J1417.7--4407, which hosts a millisecond pulsar apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of millisecond pulsar binaries that are the likely progenitors of typical field millisecond pulsars.Comment: 12 pages, 8 figures, 3 tables. Accepted for publication in Ap

Perspective Chapter: Direct Energy Deposition of Cu-Fe System Functionally Graded Materials – Miscibility Aspects, Cracking Sources, and Methods of Assisted Manufacturing

Direct energy deposition is a reliable additive manufacturing method of producing components with highly sophisticated geometry from a single material or combination of different materials with high manufacturing freedom and efficiency. The assembly operations are not required after the direct energy deposition: such complex parts as a rocket combustion chamber, a nuclear reactor element, a heat exchanger, and so on, could be fabricated layer-by-layer during one technological step. Promising applications are associated with Cu-Fe system laser deposited functionally graded components, which allow combining good oxidation resistivity, antifrictionality, thermal, and electrical conductivity of copper with mechanical strength, processability, and corrosion resistance of stainless steel. The main issue, which appears in the case of laser deposition of such materials, is internal stresses caused by significant inequality of physical properties of copper/bronze and steel, their limited miscibility, forming of brittle phases at the interface, and complexity of variation of mechanical and physical properties of the resulted alloy. The mentioned factors could cause various cracking in resulted parts. Specific techniques such as ultrasonic assistance, implementation of the external magnetic field, and post-treatment (hot isostatic pressing, machining), could be suggested to improve the quality of laser deposited Cu-Fe system functionally graded materials

FORMATION OF INSULATING BARRIERS IN SILICA POROUS FILMS BY CO2 LASER WRITING

The paper proposes the method of integral architecture formation for silica porous films used as solid-state media for different indicators. The formation of sells insulated from each other by barriers in the porous media is performed by direct laser writing using CO2laser source. We study the mechanism of laser induced modification of silica porous film with the thickness of 170±10 nm on glass substrate. We also estimate the laser processing parameters for the formation of barriers with the determined crater depth of 1.5±0.5 μm and beads height of 2.5±0.5 μm, the laser intensities in the range of q = 8.7–11.3 kW/cm2 and scanning speed of υ= 0.1-0.7 mm/s. The dependence of the laser track geometry on scanning speed and laser intensity is analyzed by optical microscopy and contact profilometry. The produced sells were impregnated with aqueous solution of copper (II) nitrate and rhodamine to demonstrate the efficiency of the insulating barriers. Looking ahead this technique can be applied for fabrication of thin film sensing devices containing different metal nanoparticles with unique optical properties