• Corrosion Science and Technology
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• v.18 no.3
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• pp.78-85
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• 2019

The International Maritime Organization (IMO) will administer a new 0.5% global sulfur cap on fuel content from 1 January 2020, lowering from the present 3.5% limit. Seawater $SO_x$ (sulfur oxide) scrubbing is especially spray scrubbing and a promising alternative to complying with the IMO regulation. However, the ionization of $SO_2$ (sulfur dioxide) and the $H_2SO_4$ (sulfuric acid) formed from $SO_3$ (sulfur trioxide) is proposed to accelerate corrosion of the internal seawater pipe. Apparently, the corrosion of the scrubber seawater piping system occurs in a severe and frequent manner. Hence, in this study, electrochemical measurement and weight loss of carbon steel (used as seawater pipe in most of the ships) in diluted sulfuric acid solution were investigated to determine corrosion rate, corrosion current density, corrosion potential, electrochemical behavior, and impressed-current density. Accordingly, the corrosion rate of carbon steel sheet in various diluted sulfuric acid solutions was observed to be greater than that in natural seawater, thus suggesting the fundamental data to deal with corrosion problems in scrubber seawater pipe.

• Corrosion Science and Technology
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• v.22 no.5
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• pp.387-392
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• 2023

The objective of this study was to evaluate corrosion resistance of Zn-Al-Mg alloy coated steel in residential water with trace quantities of Cl^-. Comparative evaluations were performed using two commercial coated steel products, GI and Galvalume, as reference samples. Examination of corrosion morphology and measurement of weight loss revealed that the Zn-Al-Mg alloy coated steel exhibited higher corrosion resistance than reference samples. This finding suggests that the alloy coated steel possesses long-term corrosion resistance not only in highly Cl^- concentrated environments such as seawater, but also in environments with extremely low levels of Cl^- found in residential water. The primary factor contributing to the superior corrosion resistance of the Zn-Al-Mg alloy coated steel in residential water is the formation of an inhibiting corrosion product composed primarily of two phases: Zn₅(OH)₆(CO₃)₂ and Zn₅(OH)₈Cl₂·H₂O. The preferential dissolution of Mg from the corroded coating layer can increase alkalinity, which might enhance the thermodynamical stability of Zn₅(OH)₆(CO₃)₂.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.20-32
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• 2024

Metal corrosion in acidic environments is a major issue in various industrial applications. This study evaluates the 4-piperonylideneaminoantipyrine (PPDAA) corrosion inhibition efficiency for mild steel in a hydrochloric acid (HCl) solution. The weight loss method was used to determine the corrosion inhibition efficiency at different concentrations and immersion time periods. Results revealed that the highest inhibition efficiency (94.3%) was achieved at 5 mM concentration after 5 hours of immersion time. To inspect the surface morphology of the inhibitor film on the mild steel surface, scanning electron microscopy (SEM) was used before and after immersion in 1.0 M HCl. Density functional theory (DFT) calculations were performed to investigate the molecular structure and electronic properties of the inhibitor molecule to understand the corrosion inhibition mechanism. Theoretical results showed that the inhibitor molecule can adsorb onto the mild steel surface through its nitrogen and oxygen atoms, forming a protective layer that prevents HCl corrosive attack. These findings highlight the potential of PPDAA as an effective corrosion inhibitor for mild steel in HCl solution. Moreover, combining experimental and theoretical approaches provides insights into the mechanism of corrosion inhibition, which is essential for developing effective strategies to prevent metal corrosion in acidic environments.

• Corrosion Science and Technology
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• v.3 no.3
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• pp.118-126
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• 2004

The correlation between sensor output and corrosion rate of reinforcing steel was evaluated by laboratory electrochemical tests in saturated $Ca(OH)_2$ with 3.5 wt.% NaCl and confirmed in concrete environment. In this paper, two types of electrochemical probes were developed: galvanic cells containing of steel/copper and steel/stainless steel couples. Potentiodynamic test, weight loss measurement, monitoring of open-circuit potential, linear polarization resistance (LPR) measurement and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion behavior of steel bar embedded in concrete. Also, galvanic current measurements were conducted to obtain the charge of sensor embedded in concrete. In this study, steel/copper and steel/stainless steel sensors showed a good correlation in simulated concrete solution between sensor output and corrosion rate of steel bar. However, there was no linear relationship between steel/stainless steel sensor output and corrosion rate of steel bar in concrete environment due to the low galvanic current output. Thus, steel/copper sensor is a reliable corrosion monitoring sensor system which can detect corrosion rate of reinforcing steel in concrete structures.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.159-165
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• 2005

Shot peening can be defined as the process of work hardening of the surface of components by means of propelled stream of spherical shot. Benefits due to shot peening are increase in resistance to fatigue, stress corrosion cracking, fretting, galling, erosion and closing of pores. In this study, the influence of shot peening on the corrosion was investigated on spring steel immersed in $3.5\%\;NaCl$. The immersion test was performed on the two kinds of specimens. Corrosion potential, polarization curve, residual stress and etc. were investigated from experimental results. From test results, the effect of shot peening on the corrosion was evaluated. The important results of the experimental study on the effects of shot peened spring steels on the environment corrosion are as follows; In case of corrosion potential, shot peened specimen shows more activated negative direction as compared with parent metal. Surface of specimen, which is treated with the shot peened, is placed as more activated state against inner base metal. It can cause the anti-corrosion effect on the base metal.

• Corrosion Science and Technology
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• v.17 no.1
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• pp.6-11
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• 2018

Outdoor exposure tests using of 7B04 aluminium alloy samples including plate, tensile and various SCC samples were carried out in Tuandao station, Shandong province (East of China) and Wanning station, Hainan province (South of China). Corrosion characteristics including weight loss, microstructure, tensile strength and SCC susceptibility were investigated. The corrosion rates in Tuandao and Wanning showed high to low and the corrosion rates changed to the following equation of $w=at^b$ (b<1). The corrosion of 7B04 aluminium alloy in Wanning was more serious than that in Tuandao. Pitting appeared at early stage of expose test, and it can be changed to general corrosion with test time extension. The 7B04 aluminium alloy of which specimen shapes are forging and thick plate also showed SCC (Stress corrosion cracking) in the marine atmosphere. The higher SCC sensitivity was observed in Wanning station than in Tuandao station. The 7B04 aluminium alloy with a high stress level was more sensitive to SCC. Intergranular and transgranular or a mixed mode of cracking can be observed in different marine exposure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.603-610
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• 2017

Steel used for various industrial fields including ammunition is vulnerable to corrosion so surface treatments are required such as plating, painting and chemical conversion coating. Zinc phosphate, used for ammunition manufacturing, is used to stick the stable compound on the surface by chemical conversion of metal. The quality of phosphate coating depends on many factors such as total acidity and iron content. In this study, we studied the influence of total acidity and iron content on coating weight and corrosion resistance of phosphate coating. The surface structure of the coating becomes dense and corrosion resistance is improved with increasing iron content. However, total acidity influences only the thickness and phosphate coating weight. In conclusion, this study suggests the optimal range of total acidity and iron content to manufacture the ammunition.

• Corrosion Science and Technology
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• v.8 no.1
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• pp.21-26
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• 2009

The influence of $H_2S$ on the corrosion of iron and the corrosion prevention mechanism of an inhibitor was investigated with a differential capacitance measurement and a weight loss measurement method. The results show that $H_2S$ accelerates both the anodic iron dissolution and the cathodic hydrogen evolution in most cases. However, $H_2S$ acts as an inhibitor of the corrosion of iron under certain special conditions. An EIS method is proposed to explain the ability of inhibitors.

• Corrosion Science and Technology
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• v.8 no.2
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• pp.45-52
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• 2009

The corrosive behavior of mild steel in 0.05 M to 10 M $H_2SO_4$ solutions containing different concentrations of tetrahydropyrimidine derivatives (THPM) was investigated using weight loss method, gasometric technique, electrochemical studies which include AC - impedance and potentiodynamic polarization method, atomic absorption studies and synergistic effect. The results obtained reveal that THPM derivatives is an efficient mixed type inhibitor but slightly anodic and it is more effective in reducing corrosion of mild steel in $H_2SO_4$ media. The adsorption of the inhibitor on the mild steel surface obeys the Langmuir adsorption isotherm. The thermodynamic parameters of adsorption reveal a strong interaction and spontaneous adsorption of THPM on the mild steel surface. The influence of temperature and inhibitor concentration on the corrosion of mild steel has also been investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.409-414
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• 2002

This study is intended to develop the self water proof admixture for durability concrete by anti-corrosion inhibitor. Chloride induced corrosion of reinforcement is one of the main factor which cause the deterioration of concrete structure. When the substitute anti-corrosion agents for a part of self waterproofing agent, the corrosion-proof increases for the increased water proofing capacity. And proper self waterproofing agent by cement weight in concrete was generally positive effect to concrete compressive strength, slump, freezing and thawing resistance. Also, permeability and absorption show a straight decrease when self waterproofing agent is added.