APATITES FORMATION ON ELECTRODEPOSITED CALCIUM PHOSPHATES IN THE Ca(NO3)2 / NH4H2PO4 AND CаCOз / Ca(H2PO4)2 SYSTEMS

Методом электрохимического осаждения на титановых пластинах при комнатной температуре в двухэлектродной ячейке при постоянной плотности тока 30 мА/см и времени осаждения 10 мин получены кальцийфосфатные покрытия: брушитные в системе Ca (NO )/ NH H PO при pH = 4 и композитные (брушит/кальцит/апатит) в системе CaCOjCa (HPO ) при pH = 5. Выдерживанием кальцийфосфатных покрытий обоих типов в модельном растворе SBF в течение 1 месяца определяли апатитообразующую способность (биоактивность). Новообразованный аморфизированный апатитовый слой после термообработки при 800°С кристаллизовался в Д -трикальцийфосфат/гидроксиапатит на брушитных покрытиях и в гидроксиапатит на композитных покрытиях за счет присутствия кальцита, карбонат-ионы которого являются инициаторами образования гидроксиапатита, а также апатитных наночастиц в исходном покрытии. Полученные кальцийфосфатные покрытия перспективны в качестве биопокрытий повышающих остеоинтеграцию металлических имплантатов. Calcium phosphate coatings on titanium plates were obtained by electrochemical deposition at room temperature in a two-electrode cell at a constant current density of 30 mA/sm and a deposition time of 10 min, and brushite coatings from Ca (NO )/NHHPO system at pH = 4, and composite (brushite/calcite/apatite) coatings from the CaCO/ Ca(HPO) system at pH = 5. The apatite-forming ability (bioactivity) was determined by soaking both types of calcium phosphate coatings in a model SBF solution during month. The newly formed amorphized apatite layer after heat treatment at 800 °С crystallized into p -tricalcium phosphate/hydroxyapatite on brushite coatings and hydroxyapatite on composite coatings due to the presence of calcite, whose carbonate ions initiate formation of hydroxyapatite, as well as apatite nanoparticles in the initial coating. The obtained calcium phosphate coatings are promising as biocoatings capable to increase osseointegration of metal implants.

Corrosion Mechanism of L360 Pipeline Steel Coated with S8 in CO2-Cl− System at Different pH Values

The corrosion behavior of L360 pipeline steel coated with or without elemental sulfur (S8) in CO2–Cl− medium at different pH was studied. An autoclave was used to simulate the working conditions for forming the corrosion scale, and an electrochemical workstation with a three-electrode cell was used to analyze the electrochemical characterization of the corrosion scale. A wire beam electrode was used to determine the potential and current distribution, and scanning electron microscopy and X-ray diffraction were used to characterize the morphology and composition of the corrosion scale. The results showed that the deposition of S8 on the surface of the electrodes caused serious localized corrosion, especially under acidic conditions. The morphology and localized corrosion intensity index further proved that the deposition of S8 significantly promoted corrosion, especially pitting corrosion. Finally, a novel corrosion mechanism of L360 pipeline steel coated with S8 in a CO2-Cl− environment under acidic conditions was proposed, and we then modeled the theoretical mechanisms that explained the experimental results.

Growth and some surface characterization of tin Sulphide (SnS) thin film by two-electrode cell arrangement for photo absorption

This study presented deposition of tin sulphide (SnS) thin film using a two-electrode electrochemical cell arrangement. The bath electrolyte comprised tin sulphate (SnSO4 ), hydrated sodium thiosulphate (Na2S2O3∙5H2O) and sulphuric acid (H2SO4 ). The acid was used to adjust the pH of the bath. The deposited film was characterised using Surface Profilometer, X-Ray Diffractometer (XRD), Uv-Visible Spectrophotometer and four point probe technique. Surface profiling revealed that the film is continuous with thickness of about 60 nm. The XRD result showed that the film has orthorhombic crystal structure. Film's crystallite size was estimated as 0.61 nm and interplanar spacing as 0.29 nm. The Uv-visible Spectrophotometer result reveals that, the film has good absorbance but poor reflectance and transmittance in the visible light region. The film has direct allowed transition with energy band gap of 1.69 eV. Values of surface resistivity and conductivity were deduced from data obtained from Four-point probe studies as 5.12 x 10-4Ω-cm and 1.96 x 103Ω-1cm-1 respectively. The I-V characteristics curve of ITO/SnS/Ag structure is linear indicating an Ohmic contact between the substrate electrode and the deposited layer. It can therefore be suggested that the film can allow pathway for photoabsorption and also aid charge transfer in photovoltaic process. Keywords: tin sulphide, orthorhombic, electrochemical deposition, characterization, photovoltaic and surface resistivity.

Frequency Dispersion of Impedance in a Molten Electrolyte

<p>It is an experimental fact that the impedance of an electrolyte as usually measured (by conductance bridge in a two electrode cell) is dependent on the frequency of the applied voltage. A quantity of fundamental physical significance in the elucidation of the structure of an electrolyte is the mobility of the conducting species. In order to know the mobilities of conducting species it is necessary to know the resistance of the particular electrolyte. However in order to establish the nature of the electrolyte i.e. its structure, resistance measurements are required which are precise and accurate and the variation of resistance (conductance) with temperature must be accurately know.</p>

Frequency Dispersion of Impedance in a Molten Electrolyte

<p>It is an experimental fact that the impedance of an electrolyte as usually measured (by conductance bridge in a two electrode cell) is dependent on the frequency of the applied voltage. A quantity of fundamental physical significance in the elucidation of the structure of an electrolyte is the mobility of the conducting species. In order to know the mobilities of conducting species it is necessary to know the resistance of the particular electrolyte. However in order to establish the nature of the electrolyte i.e. its structure, resistance measurements are required which are precise and accurate and the variation of resistance (conductance) with temperature must be accurately know.</p>

Polyaniline Thin Film Prepared by Electrochemical Polymerization Method

Polyaniline (PANI) slim film was set up by electrochemical polymerization strategy at room temperature in a standard three-electrode cell from (0.1M) aniline monomer and (0,5M) from Sulfuric acid in the presence of distilled water. The development of PANI film was portrayed by Voltammetric studies, SEM, XRD, and FTIR. Voltammetric studies were performed in 0.5 M acidic aqueous solutions using H2SO4. The XRD design demonstrated that the diffraction top at 2θ = (30˚). The FTIR spectroscopy spectra give particular and unmistakable bonds at 3500, 1572.52, 1302.53, 831.98, and 592.85 cm-1.

Gastight Rotating Cylinder Electrode: Towards Decoupling Mass Transport and Intrinsic Kinetics in Electrocatalysis

Decoupling and understanding the various mass, charge and heat transport phenomena involved in the electrocatalytic transformation of small molecules (i.e. CO2, CO, H2, N2, NH3, O2, CH4) is challenging but it can be readily achieved using dimensionless quantities (i.e. Reynolds, Sherwood, Schmidt, Damköhler, Nusselt, Prandtl, and Peclet Numbers) to simplify the characterization of systems with multiple interacting physical phenomena. Herein we report the development of a gastight rotating cylinder electrode cell with well-defined mass transport characteristics that can be applied to experimentally decouple mass transfer effects from intrinsic kinetics in electrocatalytic systems. The gastight rotating cylinder electrode cell enables the dimensionless analysis of electrocatalytic systems and should enable the rigorous research and development of electrocatalytic technologies.

Conduction of Electric Current to Organic Molecules observed by Carrier Transport Mobility Measurements

Organic semiconductors have been studied for many years, but electric current conduction through organic materials has proven difficult in practice. To evaluate the carrier mobility of newly synthesized modified polyacenes, we prepared suitable techniques for determining the physical properties of the polyacenes from electrical measurements. In a transparent electrode cell based on a low-melting-point material, we observed the dark-current dependence on the cooling rate and evaluated the sample impurity. We then developed a vertical field-effect transistor (FET) device for high- melting-point materials that easily measures the transconductance of a single drop of a sample solution. The vertical FET device provides indirect evidence of Marcus’ theory of electric conduction phenomena in aggregated organic materials.

Preparation and Electrochemical Analysis of Ni-Based Metal Organic Frameworks Containing Binary Ligands for Capacitor Electrodes

As one of the energy storage systems, supercapacitors have quite long charge-discharge cycle life. Among many kinds of electrode materials, metal organic frameworks (MOFs) have unique properties such as high specific surface areas and large pore volume as supercapacitor electrode materials. Nickel-MOFs consist of binary ligand such as 1,3,5-Trimesic acid (H3BTC) and terephthalic acid (TPA) were used as working electrode materials in three electrode cell for capacitor system. When synthesizing MOFs, it is possible to prepare uniform crystals using hydrothermal synthesis. The morphology of composites was analyzed by field emission scanning electron microscopy (FE-SEM). Electrochemical properties were measured by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) in 6M KOH electrolyte.