Strengthening and Thermally Activated Processes in an AX61/Saffil Metal Matrix Composite

AX61 magnesium alloy was reinforced with short Saffil fibres using squeeze cast technology. Samples were cut from the casting in two directions: parallel and perpendicular to the fibre plane. Samples were deformed in compression at various temperatures from room temperature to 300 °C. Various strengthening mechanisms such as load transfer, increased dislocation density, Orowan and Hall–Petch strengthening were analysed. During deformation, the stress relaxation tests were subsequently performed. The relaxation curves were evaluated with respect to Li and Feltham equations with the aim to find stress components in matrix and parameters of the thermally activated process(es).

Перенос заряда в планарных структурах на основе халькогенидной системы (As-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=-)-=SUB=-100-x-=/SUB=-Bi-=SUB=-x-=/SUB=-

The results of investigating charge-transfer processes in thin layers of a vitreous system (As_2Se_3)_100 – _ x Bi_ x are presented. A power-law dependence of the conductivity on the frequency and a decrease in the exponent s with increasing temperature are found. Charge transfer is a thermally activated process with two regions in the temperature dependence of the conductivity with the activation energies E _1 = 0.12 ± 0.01 eV and E _2 = 0.23 ± 0.01 eV, respectively. The results are explained in terms of the correlated barrier hopping (CBH) model of hopping conductivity in disordered systems. The main microparameters of the system are calculated: the density of localized states ( N ), the hopping length ( R _ω), and the largest height of the potential barrier ( W _ M ).

Chemical and Technological Thermally Activated Process Research of Roasting Pellets in Dense Bed of Conveyor Indurating Machine

The work focuses on an important scientific problem of modeling thermal processes of thermal technology, which are complicated with non-isothermal chemical reactions during the thermal preparation of raw materials in a dense layer. A mathematical model is presented for heat and mass transfer in a dense layer. The firing phosphate pellets parameters analysis calculated according to the model and performed on a kiln machinery in the scheduled mode was conducted. The features of the course of processes of drying, agglomeration and dissociation of carbonates in the pellets are revealed at their heat treatment. The received results, allow defining the temperature and gas dynamic condition of roasting the pellets for achievement of the required moisture content, necessary extent of dissociation of carbonates and the acceptable durability.

Analysis of Carrier Transport Mechanism for p-Type SnO Thin-Film Transistor

Temperature effect on the I-V characteristics of tin monoxide thin film transistors (SnO TFTs) has been analyzed. The result shows that the drain current of the SnO TFT obeys the Meyer-Neldel rule under low temperature, where current conduction is a thermally activated process. The carrier transport would be dominated by multiple trapping conduction, while, percolation conduction mechanism holds as the temperature increase.

Low Frequency Dielectric Relaxation and Charge Transport in Bi12TiO20 Photorefractive Sillenite Crystals

Features of processes of a dielectric relaxation and charge transport in photorefractive sillenite crystals Bi12TiO20 at low frequency range are investigated. It was found that the dispersion of dielectric permittivity ε' in crystals Bi12TiO20 is characterized by its growth with lowering frequency and rising temperature. This behaviour may be related to existence of dipole-relaxation polarization mechanism. The frequency dependence of dielectric loss tgδ reveals the existence of low frequency relaxation peaks in the studied temperature range. From the conductivity dependence on the frequency and temperature it was found that conductivity σ increases as frequency increases in the low frequency range. The observed dependence σ(ω)≈Аωs indicates that transport mechanism is due to hopping of carriers via localized electron states. The charge transport is thermally activated process in which activation energy Ea = (0.82±0.03) eV.

DC Electrical Ageing of XLPE under Hydrostatic Pressure

The experimental electrical ageing, of cross-linked polyethylene films 100 μm thick, was investigated under high hydrostatic pressure of 300 bar and at atmospheric pressure. The tests are conducted on direct current (dc) for up to 1000 h ageing and at temperature of 70°C. The use of the Weibull statistic, with the estimation of confidence bounds at 90%, has shown that the hydrostatic pressure has a real effect on the lifetime. These lifetime data are qualitatively analyzed with the inverse power model. It was found that thermally activated process is able to describe the pressure effect on the electrical ageing of XLPE.

Effect of Temperature on Conductivity Performance of PEO-NaI Based Polymer Electrolytes

The polymer electrolyte composed of poly (ethylene oxide) (PEO) and sodium iodide (NaI) as dopant salt was prepared by using solution casting method. Effect of temperature on the conductivity performance was studied by impedance spectroscopy in the temperature range of 303 to 343K. The linear variation of conductivity with temperature suggests the Arrhenius type thermally activated process. The effect of temperature on the conductivity is discussed on the basis of number, n, mobility, μ and diffusion coefficient, D of free ions. In this paper, n, μ and D were determined using impedance spectroscopy method.

Optimization of hydrophilic/hydrophobic phase separation in sPEEK membranes by hydrothermal treatments

The swelling behavior of sPEEK membranes: a thermally activated process associated to the β-relaxation crossover.

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

We demonstrate the kinetically controlled growth of one-dimensional Co nanomagnets with a high lateral order on a nanopatterned Ag(110) surface. First, self-organized Si nanoribbons are formed upon submonolayer condensation of Si on the anisotropic Ag(110) surface. Depending on the growth temperature, individual or regular arrays (with a pitch of 2 nm) of Si nanoribbons can be grown. Next, the Si/Ag(110) system is used as a novel one-dimensional Si template to guide the growth of Co dimer nanolines on top of the Si nanoribbons, taking advantage of the fact that the thermally activated process of Co diffusion into the Si layer is efficiently hindered at 220 K. Magnetic characterization of the Co nanolines using X-ray magnetic circular dichroism reveals that the first atomic Co layer directly adsorbed onto the Si nanoribbons presents a weak magnetic response. However, the second Co layer exhibits an enhanced magnetization, strongly suggesting a ferromagnetic ordering with an in-plane easy axis of magnetization, which is perpendicular to the Co nanolines.