Papers by Keyword: Electrochemical Methods

Abstract: The investigation of Corrosion inhibition behavior of synthesized amino acid-based Schiff base inhibitor [(E)-5-nitro-N1-((E)-3-phenylallylidene) benzene-1,2-diamine] was carried out. Its adsorption in two types of (5%) soil solutions was studied at room temperature, using potentiodynamic polarization and gravimetric techniques. The inhibition efficiency obtained at the optimum inhibitor concentration (300ppm), were 23% in acidic and 70% in neutral electrolyte. Results illustrated that the inhibitor worked well in less acidic environment in one of the soil solutions which was relatively acidic than the other. Experimental data of potentiodynamic study also indicated that the inhibitor was more inclined to adsorb on the anodic sites of the carbon steel sample, thus the inhibitor can be categorized as the anodic inhibitor due to suppression of more anodic reaction on the carbon steel sample.

Abstract: ZnO nanostructures were synthesized by two wet-chemical methods (hydrothermal and electrochemical) featuring low temperature (95°C) and atmospheric pressure onto nonwoven substrates. We investigated a hydrothermal method using reagents Zn (NO₃)₂.6H₂O and hexamethylenetetramine (HMTA) as well as an electrochemical method using ZnCl₂, and KCl containing electrolyte with H₂O₂ and/or O₂ bubbling. The surface condition of substrate material and the experimental conditions played a key role in the nanowire formation. The morphologies observed by scanning electron microscopy (SEM) include wurtzit or cabbage-like. These morphologies were found to vary with the method applied.

Abstract: The results of potentiometric titration and determination of the specific conductivity of mineralized oily wastewater from landfill areaand the results of the analysis of individual and combined model systems (bicarbonate, phosphate and hydrogen sulphide) at different volume ratios and a wide range of mineral saltsconcentrations were compared. Qualitative and quantitative characteristics of studied wastewater buffer system were defined.

Abstract: The functions of transformer oil in the transformer were insulation and cooling, its position was very important. Oil usually keeps its good oxidation resistance by adding antioxidants, the most common used antioxidants in the transformer oil was T501, the oxidation rate of oil could be delayed significantly by adding it, thereby the life of oil would be prolonged. But the electrochemical performance of oil would be affected by the excessive addition of antioxidants, so it was important to determine the content antioxidant precisely. This paper mainly studied under the three electrode system, the determined electrode material and electrode size, studied the influence of support electrolyte species on the determination of T501 by electrochemical methods, choose the most suitable electrolyte solution type. It was further demonstrated that the working electrode was a 4 mm-diameter graphite electrode, Pt coil was used as the counter electrode, the reference electrode was a calomel electrode, the optimum electrolyte was KOH, optimum organic solvent was 98% ethanol solution.

Abstract: The corrosion behavior of hot dipped Zn coating in freshwater with and without Zn(OH)₂ was investigated through weight loss test, polarization curve and impedance spectroscopy. The morphology of the corroded hot dipped Zn coating was analyzed by SEM, meanwhile, the effect of Cl^- on corrosion behavior of hot dipped Zn coating in saturated Zn(OH)₂ solution was examined using polarization curve. It was found that corrosion product Zn(OH)2 accelerate the corrosion of coating, Cl- promoted dissolution of anodic coating and incr_{Subscript text}eased the conductance of the solution, and the worst corrosion resistance of coating is Cl^-concentration of 1%.

Abstract: Many biodegradable synthetic polymers have been used as tissue-engineered scaffolds. The major problem of these polymers to be used in bone tissue engineering is their poor mechanical strength. It is well known that we can deposit hydroxyapatite, a material with strong osteoconductivity, onto a surface using electrochemical methods. These polymers, again, lack electrical conductivity so that deposition of hydroxyapatite onto these polymers is very challenging, if not impossible. Here we presented a novel scaffold for bone tissue engineering based on textile technology. First, we fabricated 316L stainless steel/poly(lactic acid) composite ply yarn by wrapping stainless steel wires and poly(lactic acid) yarn together. A 16-spindle braiding machine was then used to braid the composite yarn layer by layer into a 3-dimensional scaffold for bone tissue engineering. Furthermore, due to the electrical conductivity of 316L stainless steel wires in the composite yarn, we employed an electrochemical method to induce hydroxyapatite deposition on the braid. SEM was used to evaluate the growth of hydroxyapatite formation on the braid.

Abstract: Electrochemical material characterization method was applied to the creep specimens of 12%Cr ferritic steel to evaluate the changes in precipitates during creep. Experimental results revealed that the peak current densities “Ip1” and “Ip2” appeared at specific potentials during anodic polarization curve measurement in 1M-KOH solution. These peak current densities corresponded to the selective dissolution of several kinds of precipitates, respectively. The Ip2, which reflected the amount of M23C6 and Laves phase, increased more siginificantly with creep than thermal aging. On the other hand, the effect of applied stress was not reflected on the change in Ip1, although it increased with thermal aging and creep as well as the Ip2.

Abstract: The diesel engine in the merchant ship is being operated in severe environment more and more because temperature of exhaust gas of combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality as the oil price is significantly being jumped for recent some years. As a result, the degree of wear and corrosion in between spindle and seat ring of exhaust valve are more particularly serious compared to the other parts of the engine. Thus the repair weld to the spindle and the seat ring is a unique method to prolong the life of the exhaust valve in an economical point of view. In this study, corrosion property of both weld metal and base metal was investigated with some electrochemical methods in natural sea water solution, in case of being welded with some welding methods and welding materials to the exhaust valve specimen as the base metal. In all cases, corrosion resistance of the weld metal was considerably superior to the base metal. In particular the weld metal of A2F(AC Shielded Metal Arc Welding with two pass by foreign electrode) showed a relatively good corrosion resistance compared to the other weld metals Furthermore pitting was somewhat observed at the corroded surface of the base metal while there was no its phenomenon on the surface of the weld metal.

Abstract: Steel reinforcement concrete is one of the most widely used composite materials in architectural and civil engineering. The alkaline of concrete makes steel passive state, so the steel bars in conrete are kept in anti-corroded phase. Carbon dioxide in atmosphere, however, chemically reacts to the alkaline components in long term, and the passive state of steel is missing. Steel corrosion in concrete is not visible but it may cause decaying buildings or civil construction. The author developed the electrochemical measurement method of monitoring steel corrosion rate in concrete. With the measurement method, the author measured the variety of corrosion rates of steel reinforcement in several atmospheres, such as indoors, outdoors, in-water, underground, and so on. In this paper, found and analyzed mechanisms of steel corrosion in those atmospheres are mainly shown. For an interesting result, the most corroded sample is not the sample exposed outdoor, nor exposed in water, but the sample exposed in wet room. This may cause the diffusion balance of oxygen and water in concrete.