Papers by Keyword: Electrochemical Measurements

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Authors: Martina Ivašková, Martin Lovíšek, Katarína Miková
Abstract: Titanium and its alloys are still popular in different kind of industry. Ti-6Al-4V alloy is usually used due to its two-phased composition, which cause good mechanical properties. Corrosion resistance of this material can be improved by anodic oxidation. This electrochemical method is used to increase the thickness of titanium dioxide. The aim of the research was color anodizing of the Ti-6Al-4V alloy in the 7% H2SO4 acid solution at 20 ± 0.5°C and for 30 seconds at different voltages (15-90V). The electrochemical characteristics were determined by potentiodynamic tests in the 0.1M NaCl solution. The obtained results were analyzed by the Tafel-extrapolation method. Finally, the corrosion current densities and corrosion rates were evaluated. In fact, the corrosion rates of anodized alloys were 6 to 85 times lower against to ground surface.
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Authors: Yong Ming Sun, Hong Ling Chen
Abstract: Gemini benzimidazole cationic surfactant, propanediyl-α, ω-bis-(N-dodecyl benzimidazole ammonium bromide), referred as BIMGCS12-3, was synthesized from the raw materials of benzimidazole, dodecane bromide and dibromopropane. The structure of the target compound was confirmed by HNMR and elemental analysis. Electrochemical behaviors of BIMGCS12-3 for protecting mild steel from sulfuric acid corrosion were issued. Changes in impedance parameters (charge transfer resistance, Rct, and double layer capacitance, Cdl) were indicative of the feasibility of BIMGCS12-3 as excellent mild steel corrosion inhibitor in sulfuric acid.
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Authors: Yan Li, Jian Lin Sun, Jing Yue Chen, Hao Shi
Abstract: The silicon steel was cold rolled by using an oil-in-water emulsion for lubricating its surfaces. Oil in water (O/W) emulsion is a lubricant composed of oil in the form of droplets suspended in water. This paper mainly researched on the new emulsion which was prepared by changing the compound proportion between antioxidant 2, 6-Di-tert-butyl-p-cresol (T501) and antirust agent petroleum sodium sulfonate (T702). The corrosion behavior of the emulsion was investigated by weight loss and electrochemical methods. The mechanisms for inhibition of corrosion synergism between T501 and T702 in base oil were studied. The results show that the antirust agent (T702) can effectively forming a layer of adsorption film on the rolled strip surface and this adsorption film can segregate strip surface from air and water. The antioxidant (T501) can capture oxygenic free radical (•OH, RO•, ROO•) and carbon free radical and reduces the trend which emulsion occur oxidation reaction under high temperature and high pressure. The antioxidant plays a minor role in inhibition of corrosion synergism. The results show that the best compound proportion content is 4% antioxidant (T501) and 8% antirust agent (T702), which can effectively increase the anticorrosion effect of emulsion. Meanwhile, the self-corrosion potential and self-corrosion current of the sample is minimal and the self-corrosion current is 1.0226×10-7A/cm2.
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Authors: Hong Juan Wang, Dong Zhou, Feng Peng, Hao Yu
Abstract: Graphene with different reduction degrees was prepared by fast thermally reduction of exfoliated graphite oxide (GO) at 200-700 °C. Structure and the electrochemical capacitive performance were characterized and measured. The results show that different thermal reduction temperatures can obtain reduced graphene oxide (rGO) with different reduction degrees and influence the electrochemical capacitive performance. The rGO-400 by thermal treat at 400 °C exhibits a significantly high specific capacitance of 407 F g-1 in 6.0 M KOH electrolyte at a current density of 0.4 A g-1 and outstanding cyclic stability with 96.1% of its origin specific capacitance maintained after 2000 cycles at the current density of 10 A g-1 in GCD test.
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Authors: Benjamin Strass, Guntram Wagner, Christian Conrad, Bernd Wolter, Sigrid Benfer, Wolfram Fürbeth
Abstract: Fusion welding of dissimilar metals is in the most cases difficult or even impossible as a result of different melting points and the development of undesirable brittle intermetallic phases. This often leads to joint strengths considerable below the tensile strength of the base materials. By using Friction Stir Welding (FSW) it is possible to reduce the development of the intermetallic phases of Al/Mg-joints significantly but not to avoid them completely. Hence a hybrid welding system at the WKK of the University of Kaiserslautern was developed called “Ultrasound Supported Friction Stir Welding (US-FSW)” with the aim to shatter the brittle interlayer lines and to scatter fragments in the welding area during the FSW process. Pre-investigations have shown that for Al/Mg-US-FSW-joints the strength can be increased up to 30% in comparison to conventional FSW. Moreover for the reliable detection of nonconformities in the weld during a post-process inspection by suitable non-destructive testing (NDT) methods is necessary. Also there is a strong need for better process monitoring and control by in-process NDT methods. Furthermore the corrosion behavior of the basic materials and hybrid-joints was investigated by electrochemical methods indicating an increased corrosion of the Mg alloy in the area of the Al/Mg-butt weld.
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