Browsing by Publisher "ESG"

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    Effect of Quenching and Tempering Temperature on Corrosion Behavior of Boron Steels in 3.5 wt.% NaCl Solution
    (ESG) Aydin, G; Yazici, A
    This study was carried out to examine the impact of austenitization and tempering temperatures on the corrosion characteristics of boron steels. Boron steel samples were austenitized at 850 degrees C, 900 degrees C, and 950 degrees C, and then quenched in environmental water. After quenching, the samples were tempered at 150 degrees C, 300 degrees C, and 450 degrees C for 30 minutes to prepare specimens. The corrosion characteristics of quenched and tempered boron steels in a 3.5 wt.% NaCl solution were examined using Tafel extrapolation method. Significant statistical differences have been observed between the tested boron steels in terms of corrosion rate. Changing C concentration affected the corrosion rates of boron steels after their immersion into a 3.5 wt% NaCl solution and increasing C content generally accelerated the corrosion rate. A poor correlation has been found between average ferrite grain size and corrosion rate under the examined heat treatment conditions for tested boron steels.
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    Electrochemical Preparation and Characterization of Gold and Platinum Nanoparticles Modified Poly(taurine) Film Electrode and Its Application to Hydrazine Determination
    (ESG) Koçak, ÇC; Altin, A; Aslisen, B; Koçak, S
    A highly sensitive hydrazine sensor has been developed by using gold and platinum nanoparticles (NPs) decorated poly(taurine) on modified glassy carbon electrode (GCE). First, poly(taurine) modified glassy carbon electrode was prepared by electropolymerization method using cyclic voltammetry. Then, a thin layer of poly(taurine) is coated electrochemically on a GCE and the effective parameters have been optimized. After taurine polymerization, metal nanoparticles (Au and Pt) were doped by electrochemical reduction from metal ions solution on poly(taurine)/GCE surface. Modified electrodes were characterized by using different surface techniques. The obtaining results were compared with bare GCE, poly(taurine) modified glassy carbon electrode, AuNPs/poly(taurine)/GCE, and PtNPs/poly(taurine)/GCE. The peak potential of hydrazine oxidation on bare GCE, poly(taurine)/GCE, AuNPs/poly(taurine)/GCE, and PtNPs/poly(taurine)/GCE were observed at 690 mV, 401 mV, 341 mV, and -370 mV, respectively. Finally, these modified electrodes were successfully used for the oxidation of hydrazine and exhibited excellent electrocatalytic activity with respect to hydrazine oxidation. The better sensitivity and selectivity exhibited the amperometric techniques to compare other techniques. The linear concentration ranges were found between 0.1 to 1000 mu M (R-2 = 0.9981) for AuNPs/poly(taurine)/GCE. The limit of detection (LOD) and limit of quantitation (LOQ) values were calculated to be 0.05 mu M and 0.15 mu M, respectively. The practical application of the sensor was evaluated in river water samples with good recoveries.