DESTRUCTION MECHANISMS OF CU-ETP COPPER GUIDES FOR SECTIONAL INSULATORS OF RAILWAY TRACTION

This article presents the results of a research on the operational damage to sectional insulator guides made of hard electrolytic copper Cu-ETP (Electrolytic Tough Pitch Copper). The guides were used on various rail routes, in real conditions, on which the trains ran at maximum speeds between 40 and 120 km/h for periods of 6 or 12 months. The microstructure of the surface, the working layer of the guide, which contacts the graphite plate of the current collector and the cross-section of the guide in the place where it was damaged was examined using the Olympus light microscope. The analysis of the chemical composition in the EDS micro-regions was performed using the Zeiss Supra 53 scanning electron microscope (SEM), while the qualitative X-ray phase analysis was performed with the use of the Panalytical X'Pert diffractometer. Scratches and deformations of the surface layer characteristic of the phenomenon of friction caused by the current collector were observed in the microstructure of the damaged parts of the guides of section insulators. The effect of a very intense oxidation process was also observed, as well as the effects of an electric arc, which according to the author, is the factor that has the most destructive effect on the condition of the guides.

Improving the Performance of Constructed Wetland Microbial Fuel Cell (CW- MFC) for Wastewater Treatment and Electricity Generation

The current study deals with the performance of constructed wetland (CW) incorporating a microbial fuel cell (MFC) for wastewater treatment and electricity generation. The whole unit is referred to as CW-MFC. This technique involves two treatments; the first is an aerobic treatment which occurs in the upper layer of the system (cathode section) and the second is anaerobic biological treatment in the lower layer of the system (anode section). Two types of electrode material were tested; stainless steel and graphite. Three configurations for electrodes arrangement CW-MFC were used. In the first unit of CW-MFC, the anode was graphite plate (GPa) and cathode was also graphite plate (GPc), in the second CW-MFC unit, the anode was stainless steel mesh (SSMa) and the cathode was a couple of stainless steel plain (SSPc). The anode in the third CW-MFC unit was stainless steel mesh (SSMa) and the cathode was graphite plate (GPc). It was found that the maximum performance for electricity generation (9 mW/m3) was obtained in the unit with stainless steel mesh as anode and graphite plate as cathode. After 10 days of operation, the best result for COD removal (70%) was obtained in the unit with stainless steel mesh as anode and stainless steel plain as cathode. The effect of temperature was also investigated. The performance of unit operation for electricity generation was tested at three values of temperature; 30, 35 and 40oC. The best result was obtained at 40oC, at which the current density obtained was 80 mA/m3. A culture of Algae could grow in the unit in order to supply the cathodic region with oxygen.

THE INTERACTION POTENTIALS OF THE FULLERENE C60 MOLECULE AND CARBON NANOPARTICLES WITH A THICK GRAPHITE PLATE

В работе исследована краевая задача для модельного уравнения смешанного парабологиперболического типа третьего порядка. Доказана теорема о единственности и существовании регулярного решения исследуемой задачи. Решение исследуемой задачи выписано в явном виде. In this paper, a boundary value problem for a model inhomogeneous mixed parabolichyperbolic type equation of third order is investigated. A theorem on uniqueness and the existence of a regular solution of the problem under investigation is proved. The solution of the investigated problem is written out in an explicit form.

Effect of Electrolyte Composition on Nickel Removal Process from Artificial Electroplating Wastewater Using Two-Room Electrodeposition Cells

Research of removal of soluble nickel from artificial electroplating wastewater has been investigated. The research aim to know optimum electrolit composition in nickel electrodeposition process. This study was conducted within a batch system using double chamber electrodeposition cell separated by water hyacinth leaf. Electrodeposition cell was equipped with a copper plate as cathode, graphite plate as anode, H2SO4 anolyte, NiSO4 catholyte with Na2SO4 added as supporting electrolyte. Electrodeposition performed at 5V direct current voltage for 4 hours each running and varied the concentration of H2SO4 anolyte (0,2 M; 0,6 M and 1 M), pHinitial catholyte (2; 4 and 6) and Na2SO4 (catholyte) supporting electrolyte (0 M; 0,2 M; 0,6 M and 1 M). The statistic analysis results showed that the concentration of 0.2 M H2SO4, pHinitial catholyte of 6 and 0.2 M Na2SO4 with an optimum concentration of nickel concentration values decrease of 18,433 % and nickel deposition on the cathode of 0.042 grams.

New Materials for Semi-Insulating SiC Single Crystal Growth by PVT Method

The present research was focused on the effect of porous graphite plate in TaC-coated crucible on crystal quality and resistivity of semi-insulating SiC crystals. Two SiC crystals grown with/without porous graphite plate in TaC-coated crucible were systematically compared. 6H-SiC polytype was obtained on both crystals regardless of porous graphite plate. The quality of SiC crystal grown using porous graphite plate placed in the TaC-coated crucible was slightly better than SiC crystal without porous graphite plate. SiC crystals having an average resistivity value of about 1×1010 Ωcm were obtained. In the result of COREMA measurement, the use of porous graphite plate tends to obtain wafers with better uniformity in resistivity value.

Study on Carbon Particle Inclusions during 4H-SiC Growth by Using Physical Vapor Transport System

A study on carbon particle inclusions during 4H-SiC bulk growth is presented. Special attentions were paid to design of graphite growth compartment, size of SiC source materials, and process of seed crystal handling. It was found that common carbon inclusions with size of 30μm or less were attributed to carbon particles from graphitized SiC source. Less common carbon inclusions with size of over 100μm were also found and were attributed to poor seed crystal mounting process. In order to reduce carbon inclusions, several experiments were designed by using a NAURA Advanced Physical Vapor Transport (PVT) System APS130G. A graphite plate separator was inserted into the growth compartment to prevent the carbon particles from transporting to the growth surface. SiC powder materials with larger diameters were selected to reduce source graphitization. Additional clean process was performed to remove carbon particle residuals on graphite parts during seed mounting. The results showed significant improvement of carbon inclusion problems in SiC ingots and thus high-quality SiC wafers were made successfully.

CO2 adsorption on a modified graphite surface with sodium dodecyl sulfate surfactants: A molecular dynamics study

Molecular dynamics simulations were carried out to study adsorption of CO2 on agraphite surface at different gas concentrations. It was observed a decrement in the adsorption on the graphite surface as the CO2 concentration increased. When the graphite surface was modified by the presence of surfactant molecules, sodium dodecyl sulfate (SDS), the results indicated that gas adsorption increased with respect to the system without SDS. Analysis of density profiles were used to characterise adsorption and langmuir isotherms constructed for the systems with and without SDS-modified surfaces. Interactions between the graphite plate and CO2 were investigated in terms of pair distribution functions.