Advanced Materials Research Vol. 880

Abstract: Two setups for X-ray visualization of objects interior structure were designed and assembled in TPU. These radiographic systems are based on linear gas-discharge and GaAs semiconductor detectors. During investigation of biological object control of radiation doses has a high priority. In this report radiation dose calculations in X-ray visualization are presented. These calculation also includes dose calculations of sinograms which are used for reconstruction of tomography slices.

Abstract: The paper is devoted to the study of composite reinforcement made of glass fiber and basalt fiber, in particular their operational properties under the aggressive alkaline lightweight aggregate concrete environment. Their thermal resistance being sufficiently less than that of the regular steel composites they may be used in three-layered building envelopes to provide enhanced thermal properties. However there is lack of data and experimental results on the topic. Previous research indicated high alkali resistance of basalt fiber reinforcement, but there is a need in further studies. For the objective of the composite reinforcement that is used as flexible connectors for layer wall panels, a series of experimental studies. Research data have shown satisfactory performance study of flexible links.

Abstract: A mechanism for correlated formation of intrinsic defects F₂ centers and impurity hole centers with hydrogen bond in oxygen-containing LiF crystals is suggested.

Abstract: This paper presents experimental results of study of hydrogen accumulation in technically pure titanium alloy at saturation from gas atmosphere. Automated complex Gas Reaction Controller has been used for hydrogen saturation from gas atmosphere. Temperatures increasing from 350 °C to 500 °C allow increase hydrogen sorption process and as a result significantly increase hydrogen concentration in technically pure titanium alloy. At hydrogen saturation from gas atmosphere at temperature 500 °C increasing of saturation time from 10 minutes to 120 minutes leads to hydrogen concentration increasing from 0.1 wt.% to 1 wt.% and increasing of hydrides volume content throughout the samples. The activation energy for hydrogen evolution has been estimated by thermal desorption spectroscopy method by equal 102 kJ/mol.

Abstract: This paper presents experimental results in study of hydrogen redistribution in technically pure titanium alloy under X-ray exposure at room temperature. It is demonstrated that X-ray exposure to titanium with hydrogen affects hydrogen diffusion and redistribution from the surface area to the depth of the samples irrespective of hydrogen condition in titanium: in hydride form or dissolved state. Increase of the exposure time increases the amount of hydrogen redistributed. Hydrogen desorption during irradiation by X-rays at room temperature does not happen.

Abstract: The paper studies how microalloying with amorphous boron (B_am) and zirconia (ZrO₂) influences the structure and properties of boride coatings. Two factors are found to strongly affect the structure and phase formation in composite coatings produced by electron beam surfacing, especially when using thermoreactive powders: (i) high reactive diffusion between the composite and substrate components, which causes the coating structure degradation, and (ii) slight deviations from phase concentrations and equilibrium crystallization, which give rise to such nonequilibrium phases in the coating structure under the electron beam as ferroboron, ferrotitanium and binary eutectics.

Abstract: Sensitivity of the destructive doses of ionizing radiations, specifically radiolysis gaseous products to multipulse electric intensity of low-density polyethylene (LDPE) and a polymethyl-methacrylate (PMMA) was investigated. LDPE and PMMA were found to differ significantly depending on radiation resistance and gas permeability. The service life of the materials was basically determined by the intensity of the destruction processes at the molecular level, the macrodefects were developed at the last ageing stage . It was shown that microseconds impulses did not cause accumulation of volume charge in LDPE and PMMA. It was concluded that the ageing of polymer dielectrics affected by electric microseconds impulses did not relate to volume charge accumulation in the polymers.

Abstract: In this work the goal was to study the behavior of titanium-hydrogen system with hydrogen concentration of 1 wt. % at high temperature vacuum annealing by means of positron lifetime (PL) spectroscopy and electrical resistivity measurements. The range of hydrogen concentrations under investigation requires the γ phase formation. The study is related with the X-ray diffraction (XRD) and thermal desorption spectra (TDS) analysis. The registered positron lifetime spectra were analyzed by multiexponential decomposition into two components. Correlation of changes of the parameters of the PL spectrum and the electrical resistivity is revealed in this paper.

Abstract: Peculiarities of temperature variations on the surface of a solid under static loading are experimentally studied. We show how the surface temperature of the material under deformation is related to the stage of plastic flow and fracture. The found mechanisms can be applied to the material diagnostics during their deformation.

Abstract: The paper puts forward a modified eddy current testing method based on the use of miniature eddy current transducers within a localized controlled area of the material surface of up to 50 μm². Measurement results are provided for a model composite material made up of alternating conducting and dielectric layers of system Al-HDPE-Al. Structural flaws are specified as changes in the number and position of layers in the sequence. Prospects of the proposed method and a measuring device operating on its basis for flaw detection in composite aluminum alloy materials are shown.