This research is devoted to the study of the composition and surface morphology of extremely thin 'spin-on glass' films (similar to 20-50 nm) doped with Pt and Pd compounds in concentrations depending on the ratio of precursors in TEOS-derived sols, their aging time and heat treatment temperature. Such methods as spectrophotometry in visible and ultraviolet regions, atomic force and scanning microscopy, X-ray reflectometry, X-ray phase analysis and voltammetry were used to study processes of the formation of sols and films based on them. The authors of this study defined features of sol-gel processes based on acid hydrolysis of TEOS in presence of dopants (Pt and Pd compounds) taken separately and together. It was shown that the combination of two dopants (Pt and Pd compounds) taken in the mole ratio of 1:1 increases catalytic activity of the films towards hydrogen. (C) 2019 Elsevier B.V. All rights reserved.

The effect of alumina fibers and nanosize graphite particles on the morphology and hardness of coatings based on silicon–boron carbide–zirconium diboride composites heat-treated in air atmosphere is considered.

Ceramic matrix composites for solidification and disposal of actinide-rare-earth fraction of high-level waste (HLW) were prepared by sintering of nanosized powders of 0.8LaPO 4 –0.2Al 2 O 3 , 0.8LaPO 4 –0.2Y 2 O 3 and 0.8LaPO 4 –0.2ZrO 2 obtained from 0.8LaPO 4 · n H 2 O–0.2Al(OH) 3 , 0.8LaPO 4 · n H 2 O–0.2Y(OH) 3 and 0.8L-aPO 4 · n H 2 O–0.2ZrO(OH) 2 precursors. These powders-precursors were synthesized via sol-gel technique. After heat treatment at 850°C powders of 0.8LaPO 4 –0.2Al 2 O 3 , 0.8LaPO 4 –0.2Y 2 O 3 and 0.8LaPO 4 –0.2ZrO 2 were obtained. Further powdered compositions were stepwise sintered to prepare ceramic composites which were supposed to be used as matrices for storage of HLW. Rate of La 3+ , Al 3+ , Y 3+ and Zr 4+ leaching from ceramic matrix composites in strength aqueous solutions of NaCl and Na 2 SO 4 simulating underground brine typical for proposed location of HLW geological repository was estimated.

В работе рассмотрено влияние волокон оксида алюминия и наноразмерных частиц графита на морфологию и твердость покрытий на основе композиции кремний–карбид бора–диборид циркония, термообработанных в воздушной атмосфере.

The present work is devoted to the fabrication of silver nanoparticles by the electrochemical method. Metal silver plates served as the cathode and anode. The dependence of silver nanoparticles sizes on the experimental parameters has been investigated. The average size of metal silver nanoparticles (∼ 10 nm) was determined using laser analyzer and electron microscope equipment.

The state of the surface of organic-inorganic coatings derived by sol-gel technology on a steel surface and their effect on the reduction of the air friction losses of a mini-turbogenerator rotor were studied. Two hypotheses about the effect of the surface condition on the reduction of the air friction losses—by improving the surface smoothness and by creating a superhydrophobic surface—were suggested and tested. Smooth epoxy-titanate coatings including those doped with a fluorine-containing organosilicon polymer and superhydrophobic surfaces based on hydrolyzed methyltriethoxysilane with an aerosol additive were tested on a model mini-turbogenerator test setup. It was established that the smooth coatings reduce the total friction losses of the mini-turbogenertor by ∼5%, while the superhydrophobic coatings reduce them by ∼7%.

Nanopowders of orthophosphate LaPO4-YPO4-H2O system have been synthesized via the solgel method, and the limits of the mutual solubility of components have been specified through the calculation of the parameters of the unit cell. The dense ceramics were prepared based on the La1 − x Y x PO4 · nH2O nan-opowders at 1000 and 1200°C. The porosity, microhardness, and bending strength of the ceramics were determined, and the dependence of the microhardness on the calcination time was established. The thermal behavior of the samples was studied by dilatometric method and the thermal coefficient of linear expansion of the ceramics was estimated.

Three compositions based on epoxide-siloxane, epoxide-titanate, modified epoxide-titanate sols have been synthesized by the sol-gel method, and the morphology of surface and the hydrophobicity of coatings obtained on their basis has been studied. According to the results of the studies, the compositions of the coatings have been chosen for the conduction of tests on a rotor of high-rpm miniturbogenerator, with the aim to determine the effect of aerodynamic losses.

Slip casting procedure with subsequent firing in air is used to synthesize composites (100 − x )MoSi 2 − x M B 2 , where M = Ti, Cr, (Ti, Cr) and x = 10, 20, and 30 mol % at 900–1400°C. The MoSi 2 -CrB 2 and MoSi 2 -(Ti, Cr)B 2 composites containing 20 and 30 mol % of borides are found to possess the highest protective properties. The optimum temperature range for sintering is 1100–1400°C.

The electrophoretic precipitation of a nanodispersed BaTiO3 powder in titanium and silicon alkoxide sol systems instead of organic solvent media has been investigated. The conditions leading to formation of heterophase thin-film coatings with uniformly distributed filler particles in the SiO2 or TiO2 filmforming matrices have been found. The dependence of the BaTiO3 aggregate shape and percolation cluster type on the nature of sols has been studied.

The morphology of complexly organized structures formed in polymer matrix under the action of silver nanoparticles has been investigated using atomic-force microscopy. The analysis of the set of experimental data and the results of the theoretical calculations of the pair interaction potentials has made it possible to propose the mechanism of formation of the “flower” structure, which is based on the interactions in the far potential minimum.

Weakly absorbing films of tantalum oxide Ta 2 O 5 with the crystallization kinetics typical of amorphous films have been investigated. The films have been prepared by reactive magnetron sputtering on substrates of different natures (titanium and optical silica glass). The crystallization heat treatment of the films has been performed at temperatures ranging from 500 to 700 °C. Changes in the optical properties of the films in the visible range have been studied at the initial stage of the formation of nanosized nuclei. Investigations have been carried out using X-ray powder diffraction, atomic-force microscopy, and optical measurements. It has been demonstrated that a new reflecting layer with the refractive index smaller than that of the film is formed on polycrystalline substrates due to the heterogeneous nucleation of the crystalline phase at the film-substrate interface. The crystallization of the films on amorphous substrates occurs through the homogeneous mechanism and leads to a change in the transmission coefficient of the film as a result of light scattering from the nanocrystalline phase.

The characteristic features of the surface morphology of the films prepared by alkaline hydrolysis of silica are investigated using atomic-force microscopy. It is shown that the surface morphology of the films is influenced by the concentration of initial solutions and the modes of dehydration that are responsible for the processes of aggregation of nanoparticles, which affects the ratio between the amorphous and crystalline phases on the surface of the coating

This paper reports on the results of investigations into the surface morphology of hybrid organic-inorganic films prepared by the sol-gel method on single-crystal semiconductor silicon. The spin-on-glass films are coated from sols based on tetraethoxysilane. The chemical composition of the films is modified by introducing inorganic compounds (dopants), namely, boric acid and gadolinium nitrate, into the sols. For the purpose of increasing the film thickness, the sols are modified by small amounts (∼1 wt %) of polyols that have linear and branched structures, different molecular weights, and different numbers of active functional groups. A substantial change in the surface morphology of the spin-coated films, i.e., the formation of a specific structure of the films under the action of the above dopants and modifiers, is revealed using optical and atomic-force microscopy.