Self assembled film of thiol compounds on bronze

BOHLER;Das Land Steiermark;et al.;OMV;SANDVIK;voestalpinEuropean Corrosion Congress, EUROCORR 2015 --6 September 2015 through 10 September 2015 -- --2-aminoethanethiol (AET) and 2-mercapto-ethanol (ME) compounds have been studied for protection of bronze (CuSn5Pb5Zn5) against corrosion in test solution simulating urban rainwater (pH 5, including 0.2 g/L of each Na2SO4 and NaHCO3). The protection efficiencies were evaluated with electrochemical impedance spectroscopy (EIS) and potentiodynamic (PD) measurements. The surface of corroded samples was characterized by X-ray elemental energy dispersion spectroscopy (EDS) and scanning electron microscopy (SEM). The studied molecules are both capable for strong interaction with the copper content of bronze alloy. Also, it was anticipated that intermolecular interaction could arise due to presence of additional-OH and -NH2 end groups. For this purpose, the corrosion protection efficiency of these compounds has been investigated separately, as well as a mixture with 1:1 of molar ratio between two compounds. These bi-functional molecules exhibit strong adsorptive interaction with the alloy's surface, via-SH groups. Then the production of cupric/cuprous oxide has been diminished om the surface, the surface was protected with strongly adsorbed organic layer. It was also shown that the mixture could provide better protection efficiency, because of strong intermolecular attractions between AET and ME

Electrochemical synthesis of polyaniline on mild steel in acetonitrile-LiClO4 and corrosion performance

WOS: 000224035500036Polyaniline film could not be obtained on mild steel by direct electrooxidation of aniline in LiClO4 containing acetonitrile medium (ACN-LiClO4), because sufficient passivity of the surface could not be provided. This non-passivated metal undergoes intense dissolution, in potential region at which the monomer oxidation happens and this event prevents the formation of stable polymer film on the surface. Therefore, the electrode surface was coated with very thin polyaniline (PANi), polypyrrole (PPy) primer coatings, in monomer containing aqueous oxalic acid solution, and then the synthesis of top PANi film was achieved in aniline containing ACN-LiClO4 successfully. The corrosion behavior of PANi/PANi and PPy/PANi coated MS samples were investigated in 3.5% NaCl solution, properly. For this aim, anodic polarization curves and open circuit potential-time (E-ocp-t) variation and electrochemical impedance spectroscopy (EIS) techniques were used. It was shown that PPy/PANi coating could provide much better protection for longer periods than PANi/PANi coating against the corrosion of MS. This behavior was explained with better barrier property of PPy/PANi. After 240 h of immersion time in corrosive test solution, the protection efficiency value was 97.0%, for PPy/PANi coated electrode. (C) 2004 Elsevier B.V. All rights reserved

Anodizing and corrosion behaviour of aluminium

WOS: 000286328600018In this study, aluminum was anodized in 0.4 M H(2)SO(4) + 0.145 M H(3)BO(3) solution by means of potentiostatic method. In first step, the most appropriate conditions (anodizing voltage and period) were determined. The voltage-current behavior was investigated between 0 to 30 V and oxide formation potential (15 V) was determined. Then chorono-amperometric measurement was obtained at this potential during 2 hours. Therefore, anodizing process was applied at 15 V between aluminium anode and mild steel cathode. In the second step, the corrosion performance of non-anodized (Al) and anodized samples (Al(2)O(3)) have been investigated in 3.5% NaCl solution by using electrochemical impedance spectroscopy and polarization techniques. The interface between metal and solution was modeled with the equivalent circuit successfully. The circuit's elements were calculated with Ivium Soft fitting program. The polarization curves were obtained between -1.8 V and 0.5 V potential ranges. The experimental results proved that the thickness and quality of oxide film was improved with help of anodizing process. Thus the corrosion resistance of anodized aluminum is significantly increased.Cukurova UniversityCukurova University [FEF2007YL12]; Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)This study has been financially supported by Cukurova University research fund. The authors are greatly thankful to Cukurova University research fund (FEF2007YL12). The authors also thank to The Scientific and Technical Research Council of Turkey (TUBITAK) for financial support

Synthesis and application of phenylcarbamodithioate compound for steel protection

Phenyldithiocarbamate compound has been synthesized and studied as corrosion inhibitor for steel. Dithiocarbamate (DTC) compounds with linear alkyl groups are good inhibitors, but their stability is quite low in acidic solutions. It should be noted that long-term stability is important for practical applications, in order to avoid excess use of chemicals. So, we have synthesized phenyl substituted DTC which offers strong inhibition efficiency and extra stability. This new inhibitor is chemically adsorbed on steel through its DTC group, while the aromatic ring provides extra stability and long-term efficiency. For the assessment of corrosion kinetics, we have utilized potentiodynamic and ac impedance studies; also solution assay analysis was realized with atomic absorption spectroscopy. It was revealed that inhibitor exhibits remarkably high efficiency, even under elevated temperature conditions. At 55 °C temperature conditions, icorr value decreased from 5050 to 154 A cm-2, with the addition of 500 ppm inhibitor. The long-term stability of inhibitor was also tested and 85.93% efficiency was obtained after three days of exposure period for 500 ppm concentration. © 2016 Informa UK Limited

Optically stimulated luminescence characteristics of BeO nanoparticles synthesized by sol-gel method

Optically Stimulated Luminescence (OSL) properties of the sol-gel synthesized nano-powders of Beryllium Oxide (BeO) were investigated. Luminescence properties of BeO nanoparticles are dependent on the crystal structure, particle size, and morphology and therefore strongly dependent on the way of synthesis, thus the preparation was modified to enhance the OSL signal from the material. Structural, thermal and morphological properties of BeO in nanopowder and pellet forms were studied using X-Ray Diffraction (XRD), Fourier Transform Infrared Microscopy (FTIR), Simultaneous Thermal Analysis STA (Thermo Gravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC)) and Scanning Electronic Microscopy (SEM) techniques. XRD and STA analysis suggested an enhancement in crystallinity and thermal stability of the BeO with increasing sintering temperature. OSL dosimetric properties of the pellets prepared by pressing the synthesized powders were investigated in detail. Thermal stability of the signal as determined with a pulse heating experiment has shown that the OSL signal was stable up to depleted at around 300 °C, suggesting the suitability for dosimetric purposes. Dose response of OSL signals was observed to be linear in the dose range 0.1–100 Gy. The minimum detectable dose limit was estimated at around 100 µGy. Replicated measurements of the samples irradiated with the same dose indicated a good repeatability. Fading properties of the OSL signals were also studied up to 1 month. OSL signals of BeO pellets were decreased by approximately 11% at the end of 7 days and by about 17% at the end of 30 days when compared with the first readout. © 2018North Atlantic Treaty Organization SfP-984649, SPS Çukurova Üniversitesi: FBA-2016-6000, FYL-2015-3944, FUA-2015-4300This project has been supported by NATO in the frame of the NATO Science for Peace and Security (SPS) Programme under the project number SfP-984649 and by Çukurova University under the project numbers FUA-2015-4300 , FBA-2016-6000 and FYL-2015-3944 . We would like to thank NATO and Çukurova University Rectorate for their support

Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis

In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma-ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB:Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100 °C followed by an intense principal high temperature peak at about 260 °C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using Tm-Tstop, initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1-10 Gy and was followed by a superlinearity up to 100 Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18 MV photon beams, 6-15 MeV electron beams and a traceable 137Cs beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses. © 2016 Elsevier B.V. All rights reserved.North Atlantic Treaty Organization: SfP984649 FEF2014YL3, FUA-2015-4300 Firat University Scientific Research Projects Management Unit British Association for Psychopharmacology: 2015/54This research is sponsored by NATO ?s Emerging Security Challenges Division in the framework of the Science for Peace and Security Programme (Belgium) under the Project number SfP984649 and the Cukurova University Rectorate through the Projects FUA-2015-4300 and FEF2014YL3 . We gratefully acknowledge NATO, Belgium and Cukurova University for their financial support. We would like to thank Baskent University Hospital, Radiation Oncology Department for their permission in performing the x-ray photon irradiations and the Transfusion Center for gamma ray irradiations, and acknowledge Assoc. Prof. Dr. Aysen Yilmaz for the XRD results. We appreciate Prof. S. Ubizskii, Dr. Y. Zhydachevskii and Dr. A. Luchechko a lot analyzing spectroscopic measurements. The authors also thanks to Inonu University Scientific Research Projects Directorate (BAP) that also partially funded the project (Project number: 2015/54 )

Electrosynthesis of ZnO nanorods and nanotowers: Morphology and X-ray Absorption Near Edge Spectroscopy studies

Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. The resulting opto-electronic properties were interpreted extensively, using X-ray diffraction (XRD), X-ray Absorption Near Edge Spectroscopy (XANES), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy and four probe techniques. The ZnO deposition is mass transport controlled process and the interaction of chloride ions with the surface has great influence on diffusion kinetics, considering the substantial species (Zn 2+ and OH - ) involved in the construction of ZnO film. This effect does not change major lattice parameters, as shown with detailed analysis of XRD data. However, the texture coefficient (T c ) (0 0 2) value is higher in presence of chloride ions containing synthesis solution which gave vertically aligned, well defined and uniformly dispersed nanorods structure. The calculated E g values are in the range 3.28-3.41 eV and 3.22-3.31 eV for ZnO nanorods and nanotowers synthesized at different deposition periods, respectively. Furthermore, the charge mobility values regarding the deposition periods were measured to be in the ranges from 130.4 to 449.2 cm 2 V -1 s -1 and 126.2 to 204.7 cm 2 V -1 s -1 for nanorods and nanotowers, respectively. From XANES results, it was shown that the Zn K-edge spectrum is dominated by the transition of Zn 1s core electrons into the unoccupied Zn 4p states of the conduction band. Comparing the rod and tower nano-structured ZnO thin films, the excitation behavior of valence band electrons is different. Moreover, the density states of Zn 4p are higher for ZnO nanorods. © 2015 Elsevier B.V. All rights reserved

Physical and electronic properties of electrodeposited ZnO thin films: dependence on thickness

ZnO films have been prepared on indium tin oxide-coated glass substrates, with the help of a potentiostatic method in aqueous zinc nitrate solution. Dependence of crystallographic, optical and electronic properties on thickness of the film is reported and discussed. An increase in the film thickness causes an increase in the band and leads to an improvement in crystallinity and conductivity. The experimental results suggest a strong correlation between electronic and crystal structure of the polycrystalline wurtzite ZnO films. These observations can be used to establish guidelines for optimizing the thickness and orientation to increase the control of device performance based on ZnO thin films. © 2015, Indian Association for the Cultivation of Science.U.S. Department of Energ