Hatice Ozkazanc

Effect of Cu content on the corrosion of Al‐Si eutectic alloys in acidic solutions

Purpose – The purpose of this paper is to understand corrosion behavior of different Cu‐containing Al‐Si‐x% Cu alloys (x: 1 wt% Cu, 2 wt% Cu, 3 wt% Cu, 4 wt% Cu, and 5 wt% Cu) in 0.1 M HCl and 0.1 M H2SO4.Design/methodology/approach – Potentiodynamic, chronoamperometric and impedance measurements were applied to specimens to obtain their electrochemical characteristics. For the long‐term analyses, hydrogen evolution with immersion time (V‐t) was measured. The corroded surfaces of the alloys were investigated using scanning electron microscopy (SEM) to understand the corrosion mechanism.Findings – All experimental investigations showed that the corrosion resistance of alloys increased with increasing Cu content in the alloys.Research limitations/implications – Cu‐containing aluminum alloys are age‐hardenable alloys. The corrosion behaviour of these alloys can be changed by heat treatment. Corrosion test results for the heat treated and aged alloys will be discussed in another study.Originality/value – Al‐S...

Synthesis, Characterization, and AC Conductivity of Polyaniline/Selenium Composites

This study reports structural and thermal properties and temperature-dependent alternating current (AC) conductivity of polyaniline/selenium (PANI/Se) composites in emeraldine salt form prepared by a chemical polymerization method. Fourier transform infrared spectroscopy showed that the doping process significantly affected the N-H bond in PANI chain. The free energy change, which was calculated from the Langmuir adsorption isotherm, showed that Se was electrostatically adsorbed on PANI molecules. From the scanning electron microscopy images it was determined that morphological changes caused by the doping process on PANI surface could affect conductivity. Thermal analysis, which was performed with differential scanning calorimetry, showed that the addition of Se increased the degradation temperature of PANI. Depending on the doping level, significant increase was observed in the AC conductivity of PANI, approximately 11, 13, and 17 times for 300, 350, and 400 K temperatures respectively.

Novel Nanocomposites of Polypyrrole Doped with Fullerene C60

ABSTRACT This paper reports on the structural, thermal, and dielectric properties of polypyrrole/fullerene C60 nanocomposites synthesized by a interfacial polymerization method. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) analyses clearly indicated the existence of interactions between polypyrrole (PPy) and the fullerene C60 nanoparticles. Thermal analyses indicated that the extrapolated onset degradation temperature (Tdeg) of PPy increased with increasing doping level. Scanning electron microscopy (SEM) images showed that the fullerene C60 changed the morphology of PPy. Dielectric analyses showed a temperature dependent dielectric relaxation behavior. The relaxation time of the nanocomposites with high doping levels tended to increase with increasing temperature. This behavior of the polypyrrole/fullerene C60 nanocomposites indicated that they could be used as a high temperature ultrasonic transducer.