• Journal of the Korean institute of surface engineering
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• v.32 no.1
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• pp.31-42
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• 1999

The effect was investigated that aluminium in the zinc bath has on the coating adhesion of Hot-rolled Galvanized Iron(HGI) manufactured without pickling process. It is thought that the coating adhesion of HGI manufactured without pickling process is good due to the fact that increasing aluminium content in the zinc bath makes zinc and aluminium diffuse to the cracks or pores in the scale formed through the reduction heat treatment, and Fe-Zn-Al compound with good ductility is formed in the scale layer and plays a role of anchor between zinc coating and substrate. It is possible that HGI with the good coating adhesion was produced without pickling treatment in the zinc bath with more that 3wt% of Al content even at the $550^{\circ}C$ of conventional reduction heating temperature. In creasing the temperature of heating section and aluminium content in the zinc bath prevents the Zn-Fe alloy. The corrosion resistance of HGI manufactured without pickling process is excellent because of the mixed reaction of zinc sacrifice and aluminium passivity film.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.656-662
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• 2013

The iron oxide ($Fe_3O_4$) particles in the coolant of the secondary system of a nuclear power plant reduce the heat transfer performance or induce corrosion on the surface of the heat transfer tube. To prevent these problems, we conducted a study to improve the dispersion stability of iron oxide using polymeric dispersant injection in simulated secondary system water. The three kinds of anionic polymers containing carboxyl groups were selected. The dispersion characteristics of the iron oxide particles with the polymeric dispersants were evaluated by performing a settling test and measuring the transmission, the zeta potential, and the hydrodynamic particle size of the colloid solutions. Polymeric dispersants had a significant impact on the iron oxide dispersion stability in an aqueous solution. While the dispersant injection tended to improve the dispersion stability, the dispersion stability of iron oxide did not increase linearly with an increase in the dispersant concentration. This non-linearity is due to the agglomerations between the iron oxide particles above a critical dispersant concentration. The effect of the dispersant on the dispersion stability improvement was significant when the dispersant concentration ratio (ppm, dispersant/magnetite) was in the range of 0.1 to 0.01. This suggests that the optimization of dispersant concentration is required to maximize the iron oxide removal effect with the dispersant injection considering the applied environments, the iron oxide concentration and the concentration ratio of dispersant to iron oxide.

• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.222-235
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• 2017

First, in this study, the inhibition efficiencies of metal complexes with Cu(II), Ni(II) and Zn(II) of STSC ligand for corrosion control of mild steel in oilfield formation water were investigated. The IEs for a mixture of 500 ppm STSC and 5 ppm metal ion ($Cu^{+2}$, $Ni^{+2}$, $Zn^{+2}$) were found to be 88.77, 87.96 and 85.13 %, respectively. The results were obtained from the electrochemical techniques such as open circuit potential, linear and tafel polarization methods. The polarization studies have showed that all used Schiff base metal complexes are anodic inhibitors. The protective film has been analyzed by FTIR technique. Also, to detect the presence of the iron-inhibitor complex, UV-Visible spectral analysis technique was used. The inhibitive effect was attributed to the formation of insoluble complex adsorbed on the mild steel surface and the adsorption process follows Langmuir adsorption isotherm. The surface morphology has been analyzed by SEM. Secondly, the computational studies of the ligand and its metal complexes were performed using DFT (B3LYP) method with the $6-311G^{{\ast}{\ast}}$ basis set. Finally, it is found that the experimental results were closely related to theoretical ones.

• Journal of the Korean institute of surface engineering
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• v.21 no.2
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• pp.53-67
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• 1988

The high temperature corrosion of Fe-C alloys were studied at I atm SO gas in the temperature range 500~80$0^{\circ}C$ by means of a thermogravimetric analysis. The Na2SO4 induced high tempwrature corrosion rate was also measured at atm O2 gas under above the temperature renge. The reaction products were identified with the aid of X-ray diffraction technique, and micostruction of the alloy/scale interface was observed with a optical microscope and SEM. The experimental results were disussed by the themodeynamic calcutions. Under above the experimental condition. the reaction rates decrbon with increasing carbon content. The transfer of Fe ion was limited by a residue of carbon precipitated at alloy scale interface due to the oxidation of Fe-C alloys at alloy surface. The effect of cold working on reaction rate was different between the Fe containing low carbon and Fe-C Alloy containing carbon above 0,73 wt%. In a cold worked iron containing low carbon content, the crystallization of metal surface leads to the poor adherence between the alloy and the cavity formed between the alloy and scale. The outward diffusion of ion through the scale is estimated to be hindered by the cavity formed between the scale, consequently decreasing reaction rate. In the case Fe-C containing carbon above 0.73 Wt% alloy, the reaction rate was little affected by cold working, because the effect of content on reaction rats is greater than the effect of cold working.

• Journal of the Korean institute of surface engineering
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• v.43 no.4
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• pp.205-210
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• 2010

The A106 Gr B low carbon steel, which was used in the electric power plants and heavy chemical plants, was welded by multi-pass arc welding. The heat affected zone (HAZ) formed by welding was corroded in acid chloride solution, or in saturated $H_2S$ containing acid chloride solution, or in saturated $H_2S$ containing acid chloride solution under applied current. In this order of corrosion solution, the rate of corrosion increased, because $H_2S$ accelerated the iron dissolution, hydrogen evolution, and the formation of nonprotective FeS, whereas the applied current accelerated the electrochemical reaction. The scales formed in acid chloride solution consisted primarily of $Fe_3O_4$, while those formed in $H_2S$ containing acid chloride solution consisted primarily of $Fe_3O_4$ and FeS.

• Tribology and Lubricants
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• v.30 no.6
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• pp.356-363
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• 2014

Marine diesel engines operate in environments in which damage easily occurs from corrosion. Recently, damage to cylinder liners has increased from corrosion wear caused by increased engine power. This damage can cause serious problems in the economy. Thus, many researchers have treated and studied damaged cylinder liners. However, a method is necessary for real-time monitoring of damage to cylinder liners during operation of the engine, before serious damage can occur. This study carries out reciprocating friction and wear tests on a cast iron specimen under various corrosion atmospheres and verifies the variations of friction coefficient and friction surface. Additionally, the friction coefficient and friction status are predicted by using a neural network that learns the vibration and frequency spectrum data from an acceleration sensor. According to our conclusions, amplitude is distributed highly at high frequencies, and values of standard deviation and kurtosis are high when damage to the friction surface is serious. The accuracy rate of the friction coefficient predicted by the neural network is over 80% of the real measured value without NaCl, and application of the neural network is very effective for diagnosing the friction condition and damage to the cylinder liner.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.431-439
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• 2006

This research was conducted using a model home plumbing system composed of copper, stainless steel, galvanized iron, carbon steel, and PVC (polyvinyl chloride) pipe. The number of bacteria present in stainless steel pipe and PVC was higher than other pipes. High turbidity and zinc release were found in galvanized iron pipe material and detected during the first 6 months. Conversely, there was a decrease in turbidity and zinc release after 6 months resulting in levels similar to other pipes. Copper concentration decreased as operation times increased. In this experiment, the number of bacteria detected in biofilm for a copper pipe continued to increase. Pipe material influenced bacterial numbers in biofilm and water. This showed that elevated chlorine could not control bacterial growth in biofilm for galvanized iron and stainless steel systems. It also suggested that the dosing of chlorine might not be available for all kinds of pipes. Therefore, another complementary method should be introduced to manage biofilm effectively in water distribution systems.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.14-21
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• 2003

This study deals with the influence of ceramic coating on characteristics of friction and abrasion of aluminum allot(7075 T6) used in mechanical casting. In this research, frictional wear characteristic of ceramic coating materials such as $A1_2O_3$, $Si_3N_4$, SiC was investigated using aluminum alloy(7075 T6) and stainless 403 cast iron under room temperature and normal air pressure. The coating layer was observed using SEM. The conclusions are as follows: 1) Friction coefficients of $A1_2O_3$, SiC and $Si_3N_4$ are obtained 0.63 0.56 and 0.54 respectively. 2) Abrasion resistance of stainless 403 cast iron with $Si_3N_4$ is the best among the ceramic coating materials. 3) Abrasion mechanism of aluminum alloy(7075 T6) coaled with ceramic material and stainless 403 cast iron is caused by brittle fracture. 4) Coating the ceramic material on the aluminum alloy(7075 T6) can effectively increase the antiwear, impact properties, and corrosion resistance.

• Composites Research
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• v.36 no.4
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• pp.241-245
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• 2023

Aluminum (Al) and copper(Cu) are non-ferrous alloys with excellent electrical and thermal conductivity but have relatively lower mechanical properties than iron alloys. Stainless steel(STS), an iron alloy, is a high-strength industrial material due to its excellent mechanical properties and corrosion resistance compared to non-ferrous Al and Cu. In this research combined Al, Cu, and STS to fabricate as a functionally graded material (FGM) through a powder metallurgical process. The produced FGM exhibited lightweight and excellent surface hardness compared to copper and iron alloys and also showed higher thermal conductivity than single Al and STS materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.739-745
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• 2013

In this study, we tried to define the erosion-corrosion behavior together with the resulting effects on a pipe that is a part of a feed water circulation system according to the pipe size and hot feed water environment. An erosioncorrosion analysis was performed through the Hayduk and Minhas model based on the chemical reaction between iron and oxygen, an essential corrosive factor. The erosion-corrosion rate against the pipe diameter and feed water temperature was then evaluated by means of finite element analysis using ABAQUS. As shown in the results, the feed water temperature was the main factor influencing the erosion-corrosion rate; in particular, it was expected that the thickness of 316 stainless steel would decrease by $2.59{\mu}m$ every year in a hot water environment at $290^{\circ}C$.