Isostatic Hot Pressed W–Cu Composites with Nanosized Grain Boundaries: Microstructure, Structure and Radiation Shielding Efficiency against Gamma Rays

Abstract: The W–Cu composites with nanosized grain boundaries and high effective density were fabricated using a new fast isostatic hot pressing method. A significantly faster method was proposed for the formation of W–Cu composites in comparison to the traditional ones. The influence of both the high temperature and pressure conditions on the microstructure, structure, chemical composition, and density values were observed. It has been shown that W–Cu samples have a polycrystalline well-packed microstructure. The copper performs the function of a matrix that surrounds the tungsten grains. The W–Cu composites have mixed bcc-W (sp. gr. Im 3 m) and fcc-Cu (sp. gr. Fm 3 m) phases. The W crystallite sizes vary from 107 to 175 nm depending on the sintering conditions. The optimal sintering regimes of the W–Cu composites with the highest density value of 16.37 g/cm3 were determined. Tungsten–copper composites with thicknesses of 0.06–0.27 cm have been fabricated for the radiation protection efficiency investigation against gamma rays. It has been shown that W–Cu samples have a high shielding efficiency from gamma radiation in the 0.276–1.25 MeV range of energies, which makes them excellent candidates as materials for radiation protection. © 2022 by the authorsLicensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2020-926Funding: M.V.S. acknowledges financial support from the Ministry of Science and Higher Education of the Russian Federation within the framework of state support for the creation and development of World-Class Research Centers “Digital Biodesign and Personalized Healthcare” No. 075-15-2020-926

A Study of Ta2O5 Nanopillars with Ni Tips Prepared by Porous Anodic Alumina Through-Mask Anodization

The paper discusses the formation of Ta2O5 pillars with Ni tips during thin porous anodic alumina through-mask anodization on Si/SiO2 substrates. The tantalum nanopillars were formed through porous masks in electrolytes of phosphoric and oxalic acid. The Ni tips on the Ta2O5 pillars were formed via vacuum evaporation through the porous mask. The morphology, structure, and magnetic properties at 4.2 and 300 K of the Ta2O5 nanopillars with Ni tips have been studied using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The main mechanism of the formation of the Ta2O5 pillars during through-mask anodization was revealed. The superparamagnetic behavior of the magnetic hysteresis loop of the Ta2O5 nanopillars with Ni tips was observed. Such nanostructures can be used to develop novel functional nanomaterials for magnetic, electronic, biomedical, and optical nano-scale devices

The Interrelation of Synthesis Conditions and Wettability Properties of the Porous Anodic Alumina Membranes

The results of studies on the wettability properties and preparation of porous anodic alumina (PAA) membranes with a 3.3 ± 0.2 μm thickness and a variety of pore sizes are presented in this article. The wettability feature results, as well as the fabrication processing characteristics and morphology, are presented. The microstructure effect of these surfaces on wettability properties is analyzed in comparison to outer PAA surfaces. The interfacial contact angle was measured for amorphous PAA membranes as-fabricated and after a modification technique (pore widening), with pore sizes ranging from 20 to 130 nm. Different surface morphologies of such alumina can be obtained by adjusting synthesis conditions, which allows the surface properties to change from hydrophilic (contact angle is approximately 13°) to hydrophobic (contact angle is 100°). This research could propose a new method for designing functional surfaces with tunable wettability. The potential applications of ordinary alumina as multifunctional films are demonstrated