Advanced Materials Research Vol. 1040

Abstract: Thermal stability of the sintered samples of uranium mononitride was investigated in high purity helium atmosphere at 1900° – 2300°С. Thermogravimetry analysis of samples showed that the weight loss in uranium nitride consists of two stages. On first stage decomposition of uranium mononitride and nitrogen release starts. On the second stage additional active evaporation of uranium metal happens. During heating of the samples, nitrogen was registered by mass spectrometry. Microstructure of the samples after high temperature tests showed irregularly distributed spherical particles of uranium metal.

Abstract: Influence of modifying with silicocalcium (SiCa) on the structure and friction properties of the hypereutectoid steel alloyed with 8.85 wt. % of Cu was studied. SiCa modifying of the copper alloyed hypereutectoid steel, led to the formation of the vermicular graphite distributed in the indendritic space instead of cementite. Coefficient of friction reduction and increased wear resistance were marked in the copper alloyed hypereutectoid steel due to the presence of graphite and cupric inclusions in the steel structure. The wear resistance of the graphitized hypereutectoid steel alloyed with 8.85 wt. % of Cu was almost 5 times higher compared to the wear resistance of bronze BrA9J3L and 75% higher compared to the wear resistance of antifriction cast iron AChS-1.

Abstract: The effect of the method of aluminum nanopowder production on the aluminum products with water reaction is described. It has been established that the interaction of aluminum nanopowder prepared by the electric wire explosion, the phase composition of the reaction products mainly consists of boehmite (AlOOH) and has a fibrous structure. Therefore, that boehmite (AlOOH) can be used for modification of polymer membranes. The modified membranes can be used as water treatment from the impurity of formed true solutions according to adsorptive mechanism, and from colloidal nanometer and micron particles according to the mechanism of mechanical separation of particles depending on sizes.

Abstract: The paper presents the results of investigations of genotoxicity and morphological characteristics of nanoscale gold particles prepared by the electric spark dispersion method in a water medium. To investigate the properties we used comet assay, transmission electron microscopy, thermal desorption of nitrogen (BET). It was revealed, gold particles did not cause DNA damage at low concentrations (0.01 - 0.1 mg/ml) and detectable level of genotoxicity of gold nanoparticles is observed at concentrations of 0.3 mg/ml and above.

Abstract: In this work we performed analysis of the magnetic order of nanosized ferrimagnetic particle at the temperature and magnetic field changes, using Monte-Carlo method. The calculations take into account real mechanisms of exchange and magnetocrystalline anisotropy of ferrospinels.

Abstract: The results providing advantages of thorium-232 as a reproducing nuclide in comparison with uranium-238 as a part of nuclear fuel of new generation reactors are presented. The explanation of the effects which were found earlier in numerical simulation of parameters of open thorium - plutonium nuclear fuel cycle is offered. Scientific and technical solutions allow considering the possibility of including thorium-232 in the fuel of nuclear reactors, which are based on existing design solutions, and beginning the design of new generation materials: a new generation of fuel rods and fuel assemblies, where the isotope uranium-238 will be completely replaced with thorium-232.

Abstract: To prolong the lifetime and to improve the quality of pavements made of bituminous concretes it is necessary to apply innovative solutions during design of such building materials. The common way to increase the values of operational properties is to admix various modifying additives during production. Nanoscale additives currently constitute the big group of advanced modifiers. The known difficulty limiting the widespread practical use of nanotechnology is the necessity to ensure uniform distribution of nanoscale objects in the volume of material. Thus, to realize nanotechnology in construction it is necessary to use the various carriers for nanoscale modifiers. Several mineral materials (dolomite- and silica-based) were examined and results are presented in this paper. The optimal grain size is determined and optimal modes of grinding were identified to provide conformity of structural parameters for carriers. It is shown that total surface area of diatomite obtained by means of nitrogen absorption method is quite high due to structure of its pore space. It is stated that for structure with numerous contacts between grains, rheological properties of mixture are mostly determined by the thickness and properties of solvation shells on the grains. High surface activity of diatomite is confirmed by the rheology data. It is shown that there is the formation of adsorption layer during interaction between bitumen and surface of diatomite, and thickness of this layer is relatively high for the wide range of temperatures. It is found by means of IR spectroscopy that there is only physical sorption of bitumen on the diatomite and no new chemical compounds are forming.

Abstract: The paper deals with three-level model of polycrystal inelasticity based on crystal plasticity. This model allows to regard the most important inelastic deformation mechanisms of polycrystals including grain boundary sliding. The inflow of intragranular dislocations, changing of the boundary structure under realization of grain boundary sliding and diffusion processes are taken into account in equations for grain boundary sliding. Consistency conditions of constitutive relations at the different scale levels are used in constructing model. The results of computational experiments under uniaxial tension of a representative volume are obtained with developed model. The results show that grain boundary sliding is important and must be taking into account.

Abstract: This paper is devoted to the study of stable structures of various carbon nanomaterials using molecular dynamic simulation, study of their properties and characteristics, as well as search for possible later use in nanoelectronics and nanomechanics. We develop programs for computation of the system of atoms at every step and visualization of that data, also we research of thermodynamic properties and conditions of formation of different carbon nanostructures, try to predict existence of new materials. Nowadays we have two separate programs: one for computation and one for visualization. We continue to collect statistical data, investigate behavior of the system under different conditions.

Abstract: Hydroxyapatite and its compounds are important and promising inorganic biomaterials that can be used in dentistry and bone surgery due to its biocompatibility with the bone tissue of a living organism. The paper presents the synthesis of carbonate-substituted hydroxyapatite powders and studies their morphology, physical and chemical characteristics and biocompatibility in vivo. The synthetic carbonate-substituted hydroxyapatite are biocompatible, and they do not cause degenerative changes in the surrounding tissues. The result of this research suggests that the carbonate-substituted hydroxyapatite is promising biomaterial for orthopedic and dental prosthetics.