Papers by Keyword: Atmospheric Corrosion

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Authors: Byeong Choon Goo
Abstract: In general, structural integrity of rolling stock structures should last more than 25 years. During the lifetime corrosive degradation occurs. For structural design and diagnosis, quantitative relationship between corrosive degradation and variation of mechanical properties such as tensile strength and fatigue strength is needed. In this study, electrochemical corrosion tests, atmospheric corrosion tests and fatigue tests of corroded specimens were carried out. The electrochemical characteristics of SS400, SM490A, SUS205L and SUS304 were examined. At regular intervals tensile and fatigue tests were carried out by using specimens of SM490A and SS400 on the atmospheric corrosion test bed. The fatigue strength decreases as the atmospheric corrosion period increases. In addition, the effect of heat treatment on the tensile and fatigue behavior was studied.
Authors: Ming Zhang, Jian Fei Yu, Shan Wu Yang, Xin Lai He
Abstract: Back propagation (BP) neural network model was established, using the corrosion data of five kinds of recently developed bainite weathering steel and the commercial weathering steel 09CuPCrNi exposed in the offshore platform in Wanning. The influences of elements P, Cu, C and Cr on the corrosion behavior of weathering steel were studied according to the model. The experimental results indicate that the corrosion depth of bainite weathering steel corroded for 1 year could decline owing to the increasing contents of P, Cu and Cr in steel while C has little effect on the variation of the corrosion depth.
Authors: Kang Du, Jun Xu, Yao Hui Zhang, Zi Jie Wei
Abstract: The special atmospheric environment accelerats the corrosion process of electrical connectors in southeast coastal areas. It causes the failure probability increased and the reliability level declined. This paper discussed the most kinds of electrical connector corrosions in southeast coastal areas. The corrosion characters of the metal material used on the electrical connectors are expounded, and environmental factors in the corrosion of electrical connectors are introduced at length.
Authors: Wei Zhen Ouyang
Abstract: The atmospheric corrosion behavior of cast iron after six months immersion was studies by means of optical stereomicroscope and X-ray diffraction techniques. The results showed that active corrosion occurred on the rusted specimen covered with many thin spherical shells of solid material. The XRD analysis indicated the formation of β-FeOOH tends to increase with increasing exposure.
Authors: Pavel Krivenko, Sergii Guzii, Hameedi Abdullah Jafar Al-Musaedi
Abstract: It is known that load-bearing metallic structures that are in service in the atmospheric conditions showed that are exposed to corrosion. The known-in-the art paint-and-lacquer protective coatings can provide protection of metal surfaces for a rather short period between 5 to 10 years. That is why these structures should be protected by the more advanced coatings of new generation, namely: geocement-based coatings which differ from the known-in-the-art binding materials by formation in the hydration products of the zeolite-like minerals and feldspathoids. The paper discusses substantiation of choice of geocement composition in the (хК, уna)2O⋅Al2O3⋅nSiO2⋅mH2O system, target synthesis of hydration products of the geocements matrix in the fields of dynamic cavitation, optimal parameters of cavitation treatment aimed at nanostructurization of the geocements matrix in order to synthesize zeolite-like and hydromicaceous phases, choice of appropriate hardening agents and fillers etc. for producing highly efficient protective coatings with high corrosion resistance, high adhesion to metallic substrate and durability.
Authors: B.M. Rosales, A. Fernández, E. Ayllón, E.N. Codaro, F.E. Varela, Jorge R. Vilche
Authors: B. De Filippo, L. Campanella, A. Brotzu, S. Natali, D. Ferro
Abstract: In the main frame of the research aimed to model the corrosion growth on bronze surface, the objective of the work here reported has been to characterize the corrosion products formed on laboratory samples of bronze alloy (Cu Sn12), during the early stage of exposure to moist air with sulfur dioxide. A cycling corrosion cabinet was used to control 200 ppm gas concentration, relative humidity (RH) and temperature, according to the DIN 50018 (Kesternich test).The method is designed to evaluate how well the surface resists to sulfur dioxide corrosion; the test cycle consists of 8 hours exposure to sulfur dioxide at 40°C temperature and 100% relative humidity, followed by 12 hours drying at room condition. Weight variation, Spectrophotometer, Scanning Electron Microscopy with X-ray microanalysis (SEM-EDS), X-ray Diffraction (XRD) analysis were carried out for the tarnish products characterization. Some of the compound identified were brochantite (Cu4(OH)6SO4), chalcanthite (CuSO4•5H2O) cuprite (Cu2O), cassiterite (SnO2) and ottemannite (Sn2O3).
Authors: Chao Fang Dong, Kui Xiao, Hai Sheng, Y.H. An, Xiao Gang Li
Abstract: The aim of this work is to investigate characterizations of corrosion on 7A04 aluminum alloy with epoxy coating under simulated marine atmosphere with/without ultraviolet irradiation. The environment containing Cl- and sunlight illumination was simulated by salt spray test and UV irradiation/condensation treatment. The corrosion behavior was studied by electrochemical impedance spectroscopy, and level of coating damage was evaluated through gloss measurement. Scanning electron microscope was chosen to observe surface properties of epoxy coating/7A04 aluminum alloy system. The results show that the electrochemical characters are closely related to the aging degree of epoxy coating, which could influence the penetrating process of oxygen and corrosive medium. The coating resistance decrease, while the coating capacitance and the pore rate increase as prolonging of the test time. Along with gloss loss of epoxy coating, pores appear on the surface and the blisters break, which may act as bulk defects of epoxy coating. The coating degradation and substrate corrosion were accelerated by the cooperation of UV irradiation and salt spray. UV aging significant accelerated the deterioration of coating with larger and deeper pores compared to that of non-UV irradiation coating.
Authors: Wen Fang Cui, Chang Jing Shao, Chun Ming Liu
Abstract: The corrosion behavior of low carbon bainitic steel with Cu-P alloying in the environment simulating coastal industrial atmosphere was investigated by using dry-wet cycling corrosion test. 09CuPCrNi steel and low carbon bainitic steel without Cu-P alloying were used as comparative steels. The corrosion kinetics and electrochemical impedance spectra of the steels were measured, respectively. The morphologies of rust layers were observed by SEM and the phase constitutes of the rust layers were analyzed by XRD. Low carbon bainitic steel with Cu-P alloying behaves the lowest corrosion rate and the highest resistance of rust layer. Bainite microstructure is responsible for the uniform corrosion and the formation of dense rust layer. Cu-P alloying accelerates the transformation of gamma-FeOOH and Fe3O4 to thermodynamic stable phase alpha-FeOOH, which improves the protective effect of the rust layer.
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