Papers by Keyword: Corrosion Rate

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Authors: Ab. Aziz Farah Alina, Siti Norbahiyah, Mohd Zain Mohamad Zamzuri
Abstract: Pure Mg and AZ91D alloy was anodized with and without the gadolinium nitrate Gd (NO3)3 in different concentrations (0.001g/l, 0.025g/l, 0.05g/l, 0.075g/l and 0.09g/l) at a constant current density and treatment time of 10mA/cm2 and 5 minutes. The results showed that the optimum gadolinium concentration is 0.075g/l due to obtaining the anodic film with high corrosion resistance. The surface morphology and microstructure of anodic coating were investigated by scanning electron microscopy (SEM) , optical microscope (OM), and potentiodynamic polarization, respectively.
Authors: Sang Ll Lee, Jin Kyung Lee, Joon Hyun Lee
Abstract: The nuclear power plant has lots of pipes that the fluid of high temperature and high pressure flows. Among the pipe materials used at secondary circuit of the power plant the carbon steels are sensitive to corrosion due to their material properties. In this study, both ultrasonic test and acoustic emission test were used to study the corrosion effect for the carbon steel pipe nondestructively. The carbon steel specimens were in the pipe under 473K temperatures and 10MPa pressure conditions for corrosion processing. According to the degree of corrosion the strength of the specimen was evaluated, and the thickness of the corrosion specimens was also measured by using the ultrasonic wave. The experimental results showed that the attenuation factor was also increased as a depth of corrosion increased. The measured depth of the real corrosion by ultrasonic test shows the good agreement with that by an optical microscope. In order to understand the corrosion effect for the failure mechanism of carbon steel, a failure test on the specimen with various corrosion conditions was performed. An acoustic emission technique was also used to evaluate the degree of damage of corrosion specimen in real time. Acoustic emission technique is proved a useful method for on-line monitoring the microscopic failure mechanism and the damage location for the structures.
Authors: Ji Jie Wang, Yue Jiao Feng, Tong Cui, Da Jiang, Na Li, Yan Jing Wang
Abstract: The effect of Ca on the microstructure and corrosion properties was investigated. Vacuum induce melting was used to obtain the Mg-xCa-4Zn (wt.%) (x = 0%, 1%, 2% and 3%) alloys. Erode test was carried out in the Hank’s simulated body fluid for the alloys and the increasing of weight is carefully measured. The microstructure of the alloys was observed with optical microscope and energy spectrum analysis was used for accurate composition. It is found that as the increasing of Ca, the corrosion extent is getting serious for the Mg-xCa-4Zn alloys. Hardness increases as the adding of Ca in the alloys.
Authors: Yan Bin Huang, Gao Wei Song, Hua Dong Ding, Xue Bin Liu, Xin Hai Shao
Abstract: The solubility and cathodic protection performance of Al-Zn-In-Mg-Ga-Mn sacrificial anode in natural corrosion and self-discharge experiment was studied using electrochemistry impedance spectrum technology, weight-loss measurement and SEM. The results show that the corrosion rate of 7A52 was decreased under the protection of sacrificial anodes in the self-discharge experiment, and sacrificial anodes dissolved uniformity due to the effect of active location, the corrosion products are easy to shed. Only location corrosion occurs on the sacrificial anode’s surface which is influenced by corrosion products and oxide film in natural corrosion experiment.
Authors: Kyung Man Moon, Sung Yul Lee, Jae Hyun Jeong, Myeong Hoon Lee
Abstract: The reinforced concretes are often exposed to severely corrosive environments such as sea water, contaminated water, acid rain and seashore etc.. Therefore, the reinforced steel bar embedded in the concrete is increasingly corroded in various environments mentioned above, and this corrosion problem is thought to be very important in terms of the safety and economic points of view. In this study, a multiple mortar test specimen(W/C:0.5) with variation of coating thickness was prepared and immerged in flowing seawater for five years. And, the effects of coating thickness affecting to cathodic polarization and cyclic voltammogram were investigated using electrochemical methods. The thinner coating thickness, both invasion and diffusion of dissolved oxygen, water and chloride ion on the surface of reinforced steel bar is more easily compared to the thicker coating thickness. Thus, at the beginning of immersion, the rate of corrosion in the case of the thinner coating thickness is higher than that of the thicker coating thickness. However, it is considered that corrosion products deposited on the surface due to higher corrosion rate played the role as a resistance polarization, and increased the diffusion layer, as a result, decreased the corrosion current density compared to the thicker coating thickness. Consequently, the relationship between corrosion current density and the coating thickness were not well in good agreement with each other due to the corrosion products after being immersed for 5 years. Therefore, in order to more optimum evaluate for corrosion possibility of the reinforced steel embedded in the concrete, not only corrosion potential but also other parameters such as coating thickness, W/C ratio, and other corrosion environment should be investigated in the case of immersed in seawater for long years.
Authors: Bao Hong Hao, Ding Zeng, Quan Yong Deng, Xi Yang Song, Tin Tin Zhou
Abstract: Abstract: The paper, by using various electrochemical methods, conducts non-destructive quantitative testing towards currently-used bridges, analyzes reinforcement corrosion characteristics under natural environment, concludes the influencing rule of natural environment on reinforcement corrosion, and reveals differences accelerated simulation environment by contrasting with preliminary laboratory results. The real bridge measurement results show that: weight loss ratio of reinforcement under humid environment can reach a maximum of 33% and a minimum of 18%; while weight loss ratio of reinforcement under dry environment falls between 8%-15%. The actual measurement results also show that: box girder and guard bar coated with waterproof layer help to protect reinforcing bars inside the concrete and effectively reduce the corrosion rate inside reinforcing bars with weight loss ratio around 4-8%. It contrasts the precision of two testing methods and comes to a conclusion that testing precision of linear polarization method is higher than that of impulse current method.
Authors: Dong Ho Bae, Seong Cheol Jang, Gyu Young Lee
Abstract: In this paper, as a fundamental study to evaluate fracture characteristics and material degradation by corrosion, evaluated electrochemical corrosion and corrosion fatigue characteristics of CF8A steel using as a material of the piping system in nuclear power plant. CF8A steel was artificially degraded at 400°C for 3 months. The environmental test condition is 3.5wt.% NaCl solution of room temperature. Corrosion rate of degraded CF8A steel in NaCl solution of room temperature increases with concentration of NaCl solution increase. However, concentration of NaCl solution will be more than 4.0wt.%, it shows decreasing tendency. Crack growth rates of degraded and not-degraded CF8A steel in air condition do not show remarkable difference. However, in 3.5wt.% NaCl solution, crack growth rates of them showed higher than ones in air. Particularly, crack growth rate of degraded material remarkably increases compare to one of notdegraded material.
Authors: Shi Qi Xu, Rui Lin Xie, Li Na
Abstract: Abstract:Through physico-chemical analysis of soil under the buried pipeline, the corrosion influence factor of different ions such as 、 、 and on X80 has been studied. The result shows that when the ions concentration of 、 、 increases, the corrosion rate of X80 steel also rises and then reaches the maximum. After that, the corrosion rate begins decreasing. While for the case of ions, the corrosion rate of X80 steel keeps increasing with the concentration increase. Through detail analyzing the corrosion mechanism of different negative ions on buried pipeline steel and studying the soil corrosion rules, we can provide theoretical basis for the corrosion preventing work, which is very important and meaningful.
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%.
Authors: Jae Hong Yoon, K.S. Son, H.S. Kim, B. Mitton, R.M. Latanision, Y.R. Yoo, Young Sik Kim
Abstract: There is a need to destroy both military and civilian hazardous waste and urgency, mandated by public concern over traditional waste handling methodologies, to safe and efficient alternative technologies. One very effective process for the destruction of such waste is supercritical water oxidation (SCWO). Nevertheless, corrosion of the materials of fabrication is a serious concern. This work intends to obtain the fundamental data for developing the corrosion resistant steel for the construction of SCWO system. The effects of various factors on the corrosion resistance of flat, welded, and U-bend 316L stainless steels in Trimsol solution were studied. Corroded product on surface was composed of multi-layer with oxides and salts, and dealloying was observed. Major corrosion phenomena of 316L stainless steel under SCWO condition were intergranular corrosion, pitting corrosion, SCC, and erosion corrosion. This work focused on the elucidation of corrosion mechanism of 316L stainless steel in SCWO environment.
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