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    Corrosion of reinforcing steel in concrete immersed in chloride solution and the effects of detergent additions on diffusion and concrete porosity
    (Scientific Technical Research Council Turkey, 2002) Kahyaoglu, H; Erbil, M; Yazici, B; Yilmaz, AB
    In order to investigate the corrosion of reinforcing steel in concrete and the effects of chloride ions, oxygen diffusion and detergent additives of linear alkylbenzene (LAB) and linear alkylbenzene sulfonate (LAS), potentiokinetic experiments were carried out. Thus, by embedding steel electrodes into concrete specimens with a water/cement (W/C) ratio of 0.45, current-potential curves were obtained and the compressive strength of the specimens was measured. The electrochemical approach can be used to identify the effect of chloride on steel corrosion in concrete. It was found that the diffusion of chloride and oxygen through concrete and the reduction of oxygen on the metal surface are important parameters controlling reinforcing steel corrosion.
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    Effect of phosphate ions on electrochemical behaviour of copper in sulphate solutions
    (Maney Publishing, 2002) Kilinççeker, G; Yazici, B; Yilmaz, AB; Erbil, M
    The effect of phosphate ions oil the corrosion behaviour of copper ill sulphate solutions was investigated at different temperatures (293, 313, 333, and 353 K) and at different pH rallies (pH = 2.1, 7.2, and 12.3). A three elcctrode electrochemical technique was used for the measurements, using a saturated calomel electrode (SCE) for reference purposes. Both anodic and cathodic polarisation curves were established, from which the anodic and cathodic Tafel constants were determined. Corrosion potentials were determined by extrapolation of the anodic and cathodic Tafel lines to the point of zero current density. The results showed that for a pH value of 2.1, the corrosion rate of copper showed a Marked tendency to increase with increasing temperature ill solutions containing either sulphate alone or sulphate plus phosphate. However, at pH values of 7.2 and 12.3, this tendency became less pronounced in solutions containing sulphate alone and in solutions containing sulphate pills phosphate together, maximum corrosion rates were greatly reduced and showed less tendency to increase with increasing temperature. Anodic and cathodic reaction mechanisms are proposed to explain the observations for the corrosion of copper.
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    Effects of ammonium chloride salt added to mixing water on concrete and reinforced concrete subject to atmospheric corrosion
    (Pergamon-Elsevier Science Ltd, 2002) Yilmaz, AB; Dehri, I; Erbil, M
    Studied in this paper is the effect of SO2 as a pollutant gas on concrete and reinforced concrete specimens at various relative humidity (RH) rates prepared with ideal mixing water (IMW) and IMW + 80 mg NH4+ (NH4Cl) mixing water. The potential values of reinforcing steel were measured throughout 28 days and compressive strength values of concrete specimens in the same medium were determined at the end of the 28th day. SO2 gas was observed to have a harmful effect at higher RHs on compressive strength of concrete and to make more negative the potential values of reinforcing steel. (C) 2002 Elsevier Science Ltd. All rights reserved.
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    The effects of sulphate ion on concrete and reinforced concrete
    (Pergamon-Elsevier Science Ltd, 1997) Yilmaz, AB; Yazici, B; Erbil, M
    The effects of the sulphate ions and the pH on the strength of concrete and reinforcement steel have been investigated. Concrete and reinforced concrete samples prepared by using mixing water having different sulphate ion concentrations (standard, 400 ppm and 3500 ppm) were cured in a water bath containing the same ion concentrations of mixing water or distilled water at two different pH values (8 and 5). The samples were exposed to the environments for 90 days. The compressive strength of concrete, pH values of bath, galvanic current changes and potentials (vs. Ag/AgCl) of reinforcing steel were measured. It was observed that the compressive strength of the concrete decreases as the SO4= ion concentration increases. The galvanic currents were high for the first 28 days and then these currents decreased steadily. It was found that the potentials have been rising up to the passive potential of the reinforcing steel where the SO4= concentration is low. (C) 1997 Elsevier Science Ltd.
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    The electrochemical synthesis of poly(aniline-co-o-anisidine) on copper and their corrosion performances
    (Elsevier Science Sa, 2005) Özyilmaz, AT; Colak, N; Sangün, MK; Erbil, M; Yazici, B
    The copolymer films PANI-co-POA and poly(aniline-co-o-anisidine) were carried out on copper (Cu) electrode, by applying two different scan rates (20 and 50 mV s(-1)) and using two different thicknesses at high scan rate. Synthesizes were achieved under cyclic voltammetric conditions from 0.075 M aniline and 0.075 M o-anisidine containing sodium oxalate solutions. The synthesized copolymer films were strongly adherent and homogeneous in both cases. AC impedance spectroscopy (EIS), anodic polarization plots and open circuit potential-time curves were used to evaluate the corrosion performance of copolymer coated and uncoated electrodes in 3.5% NaCl. It was shown that the copolymer film coated at low scan rate exhibited a better property initially when compared with the copolymer film produced at high scan rate. However, it could not resist the attack of corrosion products, in longer time and meanwhile its barrier property significantly diminished. It was found that the thin copolymer film produced at high scan rate by its catalysing effect led to the formation of highly protective copper oxides on the surface whereby providing a better protection for long exposure times. It also emerged that the corrosion resistances of thin copolymer film produced at high scan rate and copolymer film synthesized at low scan rate were almost same and relatively higher for much longer periods when compared with the one observed for bare copper electrode. (c) 2005 Elsevier B.V. All rights reserved.
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    The influence of polyaniline (PANI) top coat on corrosion behaviour of nickel plated copper
    (Elsevier, 2005) Özyilmaz, AT; Erbil, M; Yazici, B
    The polyaniline (PANI) was carried out on Ni plated (1 mu m) copper (Cu/Ni). The synthesis was achieved under cyclic voltammetric conditions from 0.1 M aniline containing oxalic acid solutions. AC impedance spectroscopy (EIS) and anodic polarization curves were used to evaluate the corrosion performance of PANI coated and uncoated electrodes in 3.5% NaCl. It was found that nickel coating exhibited significant barrier property against the attack of corrosive agents. However, the porosity rate of nickel coating increased in time. PANI modified nickel plating provided much better barrier property to copper for longer periods. It was important that PANI coating by its catalyzing effect constituted lower permeability with the formation of stable nickel oxides on top of nickel plating and the catalytic behaviour of polymer film prevented increase of the porosity in longer periods, in such an aggressive medium. (c) 2005 Elsevier B.V. All rights reserved.