• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.115-121
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• 1997

This study deals with the suppressing characteristics of alkali-silica reaction by ground granulated blast-furnace slag(GGBS) in NaCl solution. NaCl contents used in the experiment ranges over 0%, 2.8% and 20%. Reactive aggregate used is Japanese andesite. Also, three GGBSs of about 4.000. 6, 000 and $8, 000cm^2/g$ were used in the experiment. The replacement proportions of portland cement by GGBSs were 40%. 60%, 70% and 80%. respectively. The specimens with GGBS were severely contracted according to the increasing replacement ratio in NaCl solution. The contraction rate increases according to the increasing in NaCl content. Also. it does with increasing the blaine fineness of GGRS. It is concluded that the suppression of alkali-silica reaction by GGBS in NaCl solution is complished by contraction of GGBS due to chloride ion induced chemical shrinkage.

• Journal of Ocean Engineering and Technology
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• v.1 no.1
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• pp.111-119
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• 1987

The corrosion fatigue crack propagation characteristics of SS41 steel in 3.5% NaCl solution have been evaluated for loading frequencies of 1Hz and 0.2Hz. A sine wave loading profile was used for fatigue testing. Each test was carried out at a constant stress ratio, R(0.1). The main results are summarized as follows; 1. Fatigue crack propagation rate was higher in 3.5% NaCl solution than in air, higher in the base metal than in the weld metal, and higher at f =0.2Hz than at f =1Hz. 2. The crack closure level of the base metal was not influenced by cyclic frequencies, but that of the weld metal was much influenced. 3. When the crack closure effect was eliminated in the evaluation of crack propagation characteristics by using $\Delta K_{eff}$, the envirommental influence was distinctly observed. At the base metal, crack propagation rate was enhanced by the hydrogen embrittlement, and the weld metal was reduced by the crac closure. 4. There was clearly observed hydrogen embrittlement and severely corroded aspect at fracture surface of lower frequency than that of higher frequency, and at that of base metal than that of the weld metal.

• Journal of the Korean Applied Science and Technology
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• v.32 no.2
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• pp.275-280
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• 2015

In this study, the current-voltage curves for stainless steel in the triethanolamine(TEA) solution was measured using the conventional three electrodes of cyclic voltammetry. Stainless steel as working electrode, Ag/AgCl electrode as reference electrode and Pt wire as counter electrode were used respectively. As a result, the C-V characteristics of stainless steel were to be for an irreversible process due to the oxidation current from cyclic voltammogram, using triethanolamine solutions. Effective diffusivity of corrosion inhibitors was decreased with increasing concentration. And the concentration of 0.5 N $NaClO_4$, $2.5{\times}10^{-3}M$ TEA solution when the corrosion inhibition effect is most great, and 1.5 N $NaClO_4$, $1.0{\times}10^{-3}M$ TEA solution, the lowest corrosion inhibition effect.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.119-120
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• 2023

Corrosion of the steel rebar in coastal environment caused huge economical loss of the globe. Therefore, coating on the steel rebar being used to mitigate the corrosion. In the present study, we have applied epoxy coating on arc thermal sprayed Al coating (a dual metal/polymeric coating) vis-à-vis compared with as coated one (Al coating). The corrosion studies were performed in simulated concrete pore solution with 3.5 wt. % NaCl solution. The morphology of the dual epoxy/Al coating is smooth while Al coating shows rankle and defects. Due to defects, Al coating is susceptible to corrosion while dual epoxy/Al coating has performed excellent compared to as coated one at extended period of immersion.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.5
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• pp.811-815
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• 1995

Effect of deamidation with Neutrase on the solubility of bovin serum albumin(BSA), egg albumin(EA), soy protein isolate(SPI) was investigated. Solubility of deamidated BSA in distilled water was decreased from 98% to 83% against native BSA at pH 4~8, minimum solubility of deamidated BSA was pH 6. Solubilities of native BSA and deamidated BSA in 0.2M NaCl solution were shown 100% as compared greately decreasing both solubilities in 1.0M NaCl at acidic pH. According to deamidation, solubility of EA in distilled water was increased below pH 4 and above pH 6, while solubility of EA in NaCl solution was decreased by deamidation at acidic pH. Solubility of SPI in distilled water was greately increased by deamidation at overall pH, deamidation was increased solubility in NaCl solution above pH 5. There was, however, no difference on solubility by deamidation below pH 5.

• Resources Recycling
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• v.23 no.6
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• pp.22-29
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• 2014

Recycling process of iron should be developed for efficient recovery of neodymium (Nd), rare metal, from acid-leaching solution of Nd magnet. In this study, $FeCl_3$ solution as iron source was used for preparation of iron nano particles with the condition of various factors, such as, reductant, and surfactant. $Na_4P_2O_7$ and Polyvinylpyrrolidone (PVP) as surfactants, $NaBH_4$ as reductant, and palladium chloride ($PdCl_2$) as a nucleation seed were used. Iron powder was analyzed by using XRD, SEM for measuring shape and size. Iron nano particles were prepared at the ratio of 1:5 (Fe (III) : $NaBH_4$). Size and shape of iron particles were round-form and 50 ~ 100 nm size. Zeta-potential of iron at the 100 mg/L of $Na_4P_2O_7$ was negative value, which was good for dispersion of metal particle. When $Na_4P_2O_7$ (100 mg/L), PVP($FeCl_3:PVP$ = 1 : 4, w/w) and Pd($FeCl_3:PdCl_2$ = 1 : 0.001, w/w) were used, iron nano particles which were round-shape, well-dispersed and near 100 nm-sized range. In this condition, $FeCl_3$ solution changed with spent Nd leachate solution, and then it is possible to be made round-formed iron nano particles at pH 9 and at the reaction bath over 20 L which is not include any surfactant.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.185-189
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• 2012

A.c. impedances of mechanically polished CP-Ti specimens were measured at open-circuit potential (OCP) with immersion time and under applied anodic potentials between -0.2 and 1 $V_{Ag/AgCl}$ in 0.1 M NaOH solution. Capacitances of native oxide films ($C_{ox,na}$) grown naturally and capacitances of anodic oxide films ($C_{ox,an}$) formed under applied anodic potentials were obtained to examine the growth of native and anodic oxide films in 0.1 M NaOH solution and how to use $C_{ox,na}$ for the surface area measurement of Ti specimen. $1/C_{ox,na}$ and $1/C_{ox,an}$ appeared to be linearly proportional to OCP and applied potential ($E_{app}$), with proportional constants of 0.086 and 0.051 $uF^{-1}\;V^{-1}$, respectively. The $C_{ox,na}$ also appeared to be linearly proportional to geometric surface area of the mechanically polished CP-Ti fixture specimen, with proportional constants of 11.3 and $8.5{\mu}F\;cm^{-2}$ at -0.45 $V_{Ag/AgCl}$ and -0.25 $V_{Ag/AgCl}$ of OCPs, respectively, in 0.1 M NaOH solution. This linear relationship between $C_{ox,na}$ and surface area is suggested to be applicable for the measurement of real surface area of Ti specimen.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.965-971
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• 2001

To estimate the reliability of 12Cr alloy steel, the material of turbine blade in the steam power plant, Its corrosion susceptibility and fatigue characteristics in NaCl and Na$_2$SO$_4$solution with the difference of concentration and temperature was investigated. The polarization tests recommended in ASTM G5 standard for corrosion susceptibility in the various corrosive solutions was estimated. It showed that the higher temperature, the faster corrosion rates and corrosion rates were the fastest in 3.5 wt.% NaCl and 1M Na$_2$SO$_4$solution. From these results, the degradation conditions were determined in distilled water, 3.5 wt.% NaCl and 1M Na$_2$SO$_4$solution at room temperature, 60$\^{C}$ and 90$\^{C}$ during 3, 6 and 9 months. Its surface had a few pits for long duration. But, it was not susceptible in sulfide and chloride condition of several temperatures. If the degraded 12Cr alloy steel and non-degraded one were compared with fatigue characteristics, Any differences were not found regardless of temperature and degradation period.

• Korean journal of food and cookery science
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• v.13 no.5
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• pp.578-584
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• 1997

Fermentation temperature and salt concentration of Dongchimi were studied for the development of low salt Dongchimi juice. The juice was prepared by soaking the radish in brine solution of 0.3∼3.0% and fermented at the temperature range of 10∼30$^{\circ}C$. The fermentation proceeded faster at higher temperature. However, the salt concentration effect was dependent on the temperature. Fermentation in 3.0% NaCl solution resulted the fastest reach to pH 3.8 followed by 0.5% NaCl at 10 and 20$^{\circ}C$, while higher NaCl concentration caused a decrease in the fermentation rate at 30$^{\circ}C$. Comparison of flavor of the juice of pH 3.9 showed that fresh sourness was high in the juice prepared at 20$^{\circ}C$ and in 0.5% NaCl. The preference test also showed the juice of pH 3.8∼4.0 fermented in 0.5% NaCl at 20$^{\circ}C$ to be the most preferable one. The salt concentration lower than 0.5% at 20$^{\circ}C$ resulted in faster fermentation and high values in turbidity. However 0.5% NaCl was scored high in flavor acceptability.

• Corrosion Science and Technology
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• v.10 no.5
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• pp.180-188
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• 2011

In the present study, denting corrosion experiments were performed as a function of crevice gap size (50, 100 and 200 ${\mu}m$) in a solution containing 3,500 ppm NaCl + 0.2 M $CuCl_2$ (pH = 3 adjusted by HCl). The effects of chloride ion concentrations (3, 3,500 and 35,000 ppm as NaCl) were also outlined with two different crevice gap sizes (100, 200 ${\mu}m$). In addition, the effect of NiB on the denting corrosion was also investigated in a solution of 35,000 ppm NaCl + 0.2 M $CuCl_2$ (pH = 3 adjusted by HCl). The results showed that denting rate increased with the increasing crevice gap size at an initial stage and became nearly constant afterwards. As the concentration of chloride ion increased, the denting rate also increased. However, the addition of a NiB powder of 4 g/L in to the acid-chloride solution was observed to suppress the denting rate significantly.