The Experts below are selected from a list of 100752 Experts worldwide ranked by ideXlab platform
Amauri Garcia - One of the best experts on this subject based on the ideXlab platform.
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The effects of a eutectic modifier on microstructure and Surface Corrosion behavior of Al-Si hypoeutectic alloys
Journal of Solid State Electrochemistry, 2007Co-Authors: Wislei R. Osório, Noé Cheung, José E. Spinelli, Pedro R. Goulart, Wislei R. Osório, José E. Spinelli, Pedro R. Goulart, Amauri GarciaAbstract:Hypoeutectic aluminum–silicon alloys can have significant improvements in mechanical properties by inducing structural modification in the normally occurring eutectic. The eutectic modification may affect not only the mechanical properties but also the Corrosion resistance of such alloys. It is well known that structural parameters such as grain size and interdendritic spacing can significantly affect Corrosion resistance of alloys. However, to date, few researches have been performed to experimentally evaluate the effects of an effective modification of eutectic morphology on Surface Corrosion behavior of Al–Si alloys. In the present study, modified and unmodified samples of an Al 9 wt.% Si alloy were solidified under similar solidification conditions, and after metallographic procedures, the Corrosion resistance was analyzed by both the electrochemical impedance spectroscopy technique and the Tafel extrapolation method carried out in a 0.5 M NaCl test solution at 25 °C. The impedance parameters and Corrosion rate were obtained from an equivalent circuit analysis. It was found that the Al-9 wt.% Si alloy casting in the modified condition tends to have its Corrosion resistance decreased when compared to the unmodified alloy.
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The roles of Al2Cu and of dendritic refinement on Surface Corrosion resistance of hypoeutectic Al–Cu alloys immersed in H2SO4
Journal of Alloys and Compounds, 2006Co-Authors: Wislei R. Osório, José E. Spinelli, Amauri Garcia, Wislei R. Osório, C. M. A. Freire, Margarita Ballester Cardona, Margarita Ballester CardonaAbstract:Abstract Al–Cu alloys castings can exhibit different Corrosion responses at different locations due to copper content and to the resulting differences on microstructural features and on Al 2 Cu fractions. The aim of this study was to investigate the influence of Al 2 Cu intermetallic particles associated to the dendritic arm spacings on the general Corrosion resistance of three different hypoeutectic Al–Cu alloys samples in sulfuric acid solution. The cast samples were produced using a non-consumable tungsten electrode furnace with a water-cooled copper hearth under argon atmosphere. The typical microstructural pattern was examined by using electronic microscopy techniques. In order to evaluate the Surface Corrosion behavior of such Al–Cu alloys, Corrosion tests were performed in a 0.5 M sulfuric acid solution at 25 °C by using an electrochemical impedance spectroscopy (EIS) technique and potentiodynamic polarization curves. An equivalent circuit was also used to provide quantitative support for the discussions and understanding of the Corrosion behavior. It was found that Al 2 Cu has a less noble Corrosion potential than that of the Al-rich phase. Despite that, dendrite fineness has proved to be more influent on Corrosion resistance than the increase on alloy copper content with the consequent increase on Al 2 Cu fraction.
Paul K. Chu - One of the best experts on this subject based on the ideXlab platform.
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Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion
Scientific reports, 2015Co-Authors: Zhang Xuming, Paul K. Chu, Xiang Peng, Hongqing Feng, Biao Gao, Kaifu HuoAbstract:Rapid Corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control Corrosion is to form a Surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the antiCorrosion behavior of Corrosion products, a special way to mitigate aqueous Corrosion is described. The concept is based on pre-Corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform Surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent Corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent Surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic Surface with the Cassie state shows better Corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-Corrosion products on magnesium alloys.
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Corrosion resistance and antithrombogenic behavior of La and Nd ion implanted stainless steels
Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2006Co-Authors: Feng Juan Jing, Fanya Jin, Y. W. Liu, Guojiang Wan, Xiong Liu, Xumei Zhao, Yongxiang Leng, Ning-kang Huang, Paul K. ChuAbstract:Lanthanide ions such as lanthanum (La) and neodymium (Nd) were implanted into 316 stainless steel samples using metal vapor vacuum arc to improve the Surface Corrosion resistance and antithrombogenic properties. X-ray photoelectron spectroscopy shows that lanthanum and neodymium exist in the +3 oxidation state in the Surface layer. The Corrosion properties of the implanted and untreated control samples were investigated utilizing electrochemical tests and our results show that La and Nd implantations enhance the Surface Corrosion resistance. In vitro activated partial thromboplastin time (APTT) tests were used to evaluate the antithrombogenic properties. The APTT time of the implanted samples was observed to be prolonged compared to that of the unimplanted stainless steel control. La and Nd ion implantations can be used to improve the Surface Corrosion resistance and biomedical properties of 316 stainless steels.
Farhad E. Ghodsi - One of the best experts on this subject based on the ideXlab platform.
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Effects of annealing atmospheres (Ar, N2 and air) on structural, morphological, and Surface Corrosion properties of a-C:H thin films
Diamond and Related Materials, 2019Co-Authors: M. Nilkar, Farhad E. GhodsiAbstract:Abstract In the present study, amorphous hydrogenated carbon (a-C:H) thin films were successfully prepared on Corning glass and stainless steel (SS) substrates via spin coating technique from a polymeric solution through thermal decomposition. For the first time, the effects of annealing atmospheres consisting of argon, nitrogen, and air on the structural, vibrational, and morphological properties of the films deposited on Corning glass substrates were investigated by Raman spectroscopy, FTIR spectroscopy, AFM, and FE-SEM. The Surface Corrosion tests of uncoated and a-C:H coated stainless steel (SS) substrates were evaluated by potentiodynamic polarization analysis. The results indicated that diamond like carbon (DLC) character, Surface roughness as well as Surface Corrosion resistance behavior of the specimens depend on the type of annealing atmosphere. The films annealed under N2 exhibited smoother Surface with lower sp3 fraction, while annealing in Ar caused to increase roughness with the higher sp3 fraction. It was also found that in all the samples, a-C:H coating acted as a proper barrier between the substrate and the corrosive medium. Especially, Ar-annealed a-C:H coating could be a candidate as a Surface Corrosion-resistance coating due to low Surface Corrosion current density and broad passivity region of anodic polarization branch. Furthermore, the fabricated a-C:H thin films involved with high film thickness controllability and good adhesion without needing the interlayer materials.
M.h. Nazir - One of the best experts on this subject based on the ideXlab platform.
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Time dependent Surface Corrosion analysis and modelling of automotive steel under a simplistic model of variations in environmental parameters
Materials Chemistry and Physics, 2016Co-Authors: Adil Saeed, Zulfiqar Ahmad Khan, M.h. NazirAbstract:Abstract This research presents time-dependent Corrosion analysis of automotive steel utilised in a large military vehicle in real operating environment, followed by simulated environmental tests and simplistic Surface Corrosion modelling. Time-dependent Surface Corrosion accumulated on this specific component was observed to be approximately 250 μm thick, with the identification of Surface contaminants such as chlorine and sulphur. Simulated environmental tests considering temperature and relative humidity variations were performed to evaluate quantitative Corrosion damage to the structure of the vehicle. The relationship of various temperatures and relative humidity with respect to time, within the context of Corrosion initiation and propagation, has been presented. A mathematical model to incorporate Corrosion accumulation on the Surfaces derived from the simulated environmental tests is presented.
Charles R. Westgate - One of the best experts on this subject based on the ideXlab platform.
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Moisture-induced Surface Corrosion in AZO thin films formed by atomic layer deposition
IEEE Transactions on Device and Materials Reliability, 2012Co-Authors: Tara P. Dhakal, Abhishek S. Nandur, Parag Vasekar, Daniel Vanhart, Mohammad M. Hamasha, Susan Lu, Anju Sharma, Charles R. WestgateAbstract:Aluminum-doped zinc oxide (AZO) thin film is a viable alternative\nto tin-doped indium oxide, the dominant transparent conducting oxide\nused in solar cells. The durability of the AZO thin films grown by\natomic layer deposition technique, which is known to form layers\nwith atomic layer precision, is studied. The AZO films were subjected\nto the harsh environmental conditions of varying temperatures and\nhumidity, and their changes in Surface morphology and conductivity\nare investigated. Four different combinations of temperature (100�C\nand 20�C) and relative humidity (100% and 20%) were used. It was\nfound that the films exposed to the high-moisture and temperature\nconditions resulted in Surface Corrosion and lowered conductivity.\nHowever, SEM cross-sectional images showed that the bulk of the film\nwas unaffected. The corroded Surface had contaminants deposited from\nthe measurement chamber as observed from XPS elemental analysis.\nDetailed phase analysis showed the presence of zinc hydroxide and\nzinc carbonate inside the corroded regions.
