Papers by Keyword: Corrosion Behavior

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Authors: Xia Zhao, Shuan Liu, Bao Rong Hou
Abstract: nanoZrO2 was modified by styrene coupling grafting method and then used as an additive to improve the protective performance of epoxy coating. Two kinds of coatings, neat epoxy coating and nanoZrO2/epoxy coating, were prepared and applied on Q235 carbon steel plates. The plates were submitted to salt spray chamber and seawater immersion for 1000 hours to evaluate the corrosion protection performance for these two kinds of coatings. Tafel polarization curves and electrochemical impedance spectroscopy (EIS) were determined to analyze the corrosion behavior of coating/metal system. Scanning electron microscopy (SEM) and photographs were carried out for morphology analysis of two kinds of coatings under different conditions. Results showed a superior stability and efficient corrosion protection by nanoZrO2 /epoxy coating. The modified nanoZrO2 could inhibit the penetration of corrosive media and then improve the corrosion protection of the epoxy coating on carbon steel.
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Authors: Aphinan Phukaoluan, Anak Khantachawana, Pongpan Kaewtatip, Surachai Dechkunakorn
Abstract: The aim of this study, the corrosion behavior of TiNiCu in artificial saliva (pH5.35) at 37°C was assessed by the use of electrochemical methods. Ti50Ni43Cu7 (at%) used in this study were made from ingots prepared by the vacuum arc melting (VAM) method. The furnace was purged with argon gas during melting. All melted ingots were then homogenized at 800°C for 3.6 ks. Open circuit potential (OCP) was monitored at 3.6 ks followed by potentiodynamic techniques. The results showed that all chemical composition of orthodontic wires by EPMA were Ti, Ni, Cu, Cr, Fe and Mn. Surface roughness was measured in order to ensure that TiNiCu and SS was significant difference which might affect corrosion resistance. It was seen that TiNiCu orthodontic wires, presented a good corrosion resistance, compared to the stainless steel, probably due to the formation of a protective oxide film mainly constituted by titanium oxide.
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Authors: Hamid Reza Bakhsheshi Rad, Mohd Hasbullah Idris, Mohammed Rafiq Abdul Kadir, Saeed Farahany, Amir Fereidouni, Mohd Yazid Yahya
Abstract: In the present study binary Mg-xCa (x=0.5 and 1.25wt.%) and ternary Mg-1Ca-xZn (x=0.5 and 1.5wt.%) alloys are produced by casting the molten metal in a metal die at a temperature of 740°C. The microstructure analysis of the Mg-Ca and Mg-Ca-Zn alloys were studied by OM, SEM and EDX. The corrosion behavior of alloys was evaluated via potentiodynamic polarization test in Kokubo solution. The result exhibited that the grain size decrease with rising Ca content in Mg-Ca alloys and degree of grain size reduction further decreased by adding Zn to Mg-1Ca-Zn alloys. The microstructure of Mg-Ca alloys were constituted of primary Mg and lamellar eutectic (α-Mg+Mg2Ca) phase, Whilst Mg–1Ca-Zn alloys were composed of primary Mg and eutectic (α-Mg+Mg2Ca+Ca2Mg6Zn3) phases. In addition with increasing Ca and Zn the amount of Mg2Ca and Ca2Mg6Zn3 increased respectively in grain boundaries. Electrochemical test shows that the addition of Zn leads to improve corrosion resistance of the Mg–1Ca-Zn alloys as a result of the formation of Ca2Mg6Zn3 phase, whilst the addition of more than 0.5 wt% Ca to Mg-Ca alloys result in decrease corrosion resistance due to the formation Mg2Ca.
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Authors: Xin Zhang, Xia Deng, Kui Zhang, Xing Gang Li, Yang Shi, Yu Long Zhang, Min Peng, Ling Ying Kong
Abstract: The corrosion mechanisms of as-cast Mg-8Y and Mg-5Y-7Gd-1Nd-0.5Zr Mg alloys in 5% NaCl aqueous solution were investigated by electrochemical testing and SEM observation. The electrochemical results indicated that the corrosion resistance of Mg-8Y and Mg-5Y-7Gd-1Nd-0.5Zr alloys in 5% NaCl aqueous solution gradually deteriorated with increasing of immersion time expect for 2h and 24h immersion. The Cl- anion led to the initiation and development of the corrosion pits. The cathodic reaction was driven by hydrogen evolution reaction. The presence of filiform corrosion also proved a resistant oxide film naturally formed on the surface of Mg-8Y and Mg-5Y-7Gd-1Nd-0.5Zr alloys. The corrosion resistance of Mg-5Y-7Gd-1Nd-0.5Zr was better than Mg-8Y.
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Authors: Li Ping, Wang Ying
Abstract: The corrosion behavior of reinforcing bar HRB400 in simulated concrete solution (0.5 wt.% NaCl solution) was investigated, and its tensile mechanical properties were tested before and after corrosion. The results show that, with the increase of corrosion time from 240h to 720h, the corrosion rate increases and the corrosion becomes heavier and heavier, and the composition amounts of corrosion scale are similar. After 720h, the yield strength and tensile strength are decreased by less than 10%, and the elongation are decreased by more than 20%.
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Authors: Zhi Chao Qiu, Xiang Liu, Na Zhang
Abstract: Corrosion experiments were applied for 13Cr steel. Through the experiments, the corrosion rate of 13Cr steel in different temperature was tested. The corrosion rate of 13Cr steel was increased with the increase of temperature. Moreover X-ray diffraction analysis and scanning electron microscope analysis were applied to understand the corrosion behavior of 13Cr in micro-scale.
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Authors: Zhi Chao Qiu, Xiang Liu, Na Zhang
Abstract: Corrosion experiments were done to test the corrosion behavior of 3Cr steel in different water cut content. The experimental result shown that with the increase of water cut, the corrosion rate was increase especially in the high water cut environment. From XRD and SEM analysis result, the corrosion composition was changed with the water cut content. The corrosion film became less protective with the increase of water cut.
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Authors: Long Huang, Shan Shan Luo, Wen Kui Li
Abstract: Al2O3 materials were used in a very wide range due to its good mechanical properties and relative low manufacture cost. The corrosion resistance of Al2O3 materials in acid, alkaline and sea water solutions gained more and more attention because many application situations are severe and the working life is shorten due to the corrosion. In this paper, the corrosion behavior of Al2O3 based materials in acid and alkaline solutions was studied and effect of corrosion time on the corrosion behavior of Al2O3 materials was investigated. The microstructure of as prepared Al2O3 materials was characterized by SEM. Possible corrosion process and mechanism was discussed in details. The results reveal that the as prepared Al2O3 materials show better corrosion resistance in alkaline solution than in acid solutions. In both acid and alkaline conditions, the corrosion mainly occurs in the grain boundary. Mass loss increased with increasing corrosion time, while the corrosion rate was decreased.
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Authors: Ju Mei Zhang, Zhi Hu Wang, Hui Cai, Ming Zhu, Li Bin Niu
Abstract: The microstructure and corrosion behavior of commercial AZ91/AZ91-0.4%Nd alloys were investigated by OM, immersion test and weight-loss method. It was found that the number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency, the coarse β-Mg17Al12 phase distributed along the grain boundaries transformed into granular, and the granular or acicular Al3Nd phase precipitated in matrix. The addition of Nd element significantly reduces the corrosion rate of AZ91-0.4%Nd magnesium alloy, as a result the corrosion resistance of alloy was improved obviously.
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Authors: Wan Qiu Zhou, Xin Li, Ting Ting Huang, Jian Wang, Shi Gang Xin, Yan Hong Kang
Abstract: Polyaniline (PANI) polymer coating was electrochemically synthetised by cyclic voltammetry (CV) method on stainless steel bipolar plates of proton exchange membrane fuel cell (PEMFC). Structure and morphology of PANI polymer coating were characterized by means of fourier transform infrared reflection (FTIR) spectrum and scanning electron microscopy (SEM). The corrosion behavior of the coating was evaluated by polarization curve and electrochemical impedance spectroscopy (EIS) in the medium of 1M H2SO4 and 2ppM NaF at 70°C to simulate the corrosive condition of PEMFC. It was found that the optimal conditions for PANI polymer coating synthesis could be 10-15 circles when the voltage ranged from-1.2V to +1.2V(Vs.SCE) with a scan rate of 50 mV/s. SEM observation results indicated that the polymer coating presented with uniform and dense feature. FTIR results illustrated that the coating were composed of PANI. Corrosion current densities of 316L SS and PANI-coated steel were 10-5 and 10-6 A/cm2 respectively. Corrosion potential of the coated SS shifted towards more positive values compared to the uncoated plate. EIS results indicated that the radius of the capacity impedance for PANI increased obviously.
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