• Nuclear Engineering and Technology
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• 제54권3호
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• pp.984-990
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• 2022

Corrosion release behavior of Alloy 690 in high-temperature water was investigated under the conditions of injected Zn concentrations of 0 ppb, 10 ppb and 50 ppb. A protective oxide film composed of Zn(Fe_xCr_1-x)₂O₄ and Cr₂O₃ was formed with Zn injection, resulting in a better corrosion resistance. In comparison with the Zn-free condition, the corrosion release rate under the Zn-injection conditions was smaller. The corrosion release inhibiting factors were 1.7 and 1.9 under the conditions of 10 ppb and 50 ppb Zn-injection respectively. A foreseen application of the corrosion and corrosion release rates has been proposed and discussed.

• Environmental Engineering Research
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• 제17권1호
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• pp.17-25
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• 2012

Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.

• 상하수도학회지
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• 제20권2호
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• pp.215-223
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• 2006

The internal corrosion of water distribution systems is the main cause for the problem of the public health threat as well as water leakage in the damaged pipeline, red water, and odor and taste of the tap water. This study was examined the effect of chemicals used for pH and alkalinity control and corrosion inhibitors for producing the optimal corrosion control method. Corrosion study at different pH and alkalinity indicated that these control using alkaline chemicals was effective in corrosion rate, Fe release reduction, but examined to be increased in turbidity and corrosion-by-products(TTHMs) problems. The turbidity was slightly increased, requiring caution in controlling corrosion with $Ca(OH)_2$. At pH 9.0, TTHMs concentration is increased two times corn pared with non-control of pH. Using the pipe which had experienced 28 years of exposure, iron release was decreased with the corrosion inhibitor. Consequently, pH, Alkalinity control method using alkaline chemicals must be complemented by corrosion inhibitor application for efficient corrosion control.

• Corrosion Science and Technology
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• 제7권4호
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• pp.212-218
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• 2008

Inorganic ion exchange compounds (IECs) including hydrotalcites and bentonite clays are a well known classes of layered mixed metal hydroxides or silicates that demonstrate ion exchange properties. These compounds have a range of applications from water purification to catalyst supports. The use of synthetic versions of these compounds as environmentally friendly additives to paints for storage and release of inhibitors is a new and emerging application. In this paper, the general concept of storage and release of inhibiting ions from IEC-based particulate pigments added to organic coatings is presented. The unique aspects of the IEC structure and the ion exchange phenomenon that form the basis of the storage and release characteristic are illustrated in two examples comprising an anion exchanging hydrotalcite compound and a cation exchanging bentonite compound. Examples of the levels of corrosion protection imparted by use of these types of pigments in organic coatings applied to aluminum alloy substrates is shown. How corrosion inhibition translates to corrosion protection during accelerated exposure testing by organic coatings containing these compounds is also presented.

• Corrosion Science and Technology
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• 제14권4호
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• pp.166-171
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• 2015

Knowledge of how metal releases from the stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessment. A new European standard test protocol for testing metal release in food contact materials made from metals and alloys has recently been published by the Council of Europe. The major difference from earlier test protocols is the use of citric acid as the worst-case food simulant. The objectives of this study were to assess the effect of citric acid at acidic, neutral, and alkaline solution pH on the extent of metal release for stainless steel grades AISI 304 and 316, commonly used as food contact materials. Both grades released lower amounts of metals than the specific release limits when they were tested according to test guidelines. The released amounts of metals were assessed by means of graphite furnace atomic absorption spectroscopy, and changes in the outermost surface composition were determined using X-ray photoelectron spectroscopy. The results demonstrate that both the pH and the complexation capacity of the solutions affected the extent of metal release from stainless steel and are discussed from a mechanistic perspective. The outermost surface oxide was significantly enriched in chromium upon exposure to citric acid, indicating rapid passivation by the acid. This study elucidates the effect of several possible mechanisms, including complex ion- and ligand-induced metal release, that govern the process of metal release from stainless steel under passive conditions in solutions that contain citric acid.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2306-2310
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• 2010

상수도관의 부식은 수돗물이 공급되는 과정에서 관 표면의 금속과 물 사이의 일련의 복잡한 산화/환원 반응이다. 부식으로 인해 발생할 수 있는 1차적인 고려사항은 철, 납, 동과 같은 독성이 있는 중금속이 물속에 존재할 수 있다는 것이며, 이는 상수도관에 악영향을 미치며, 세탁물을 훼손하거나 맛을 낼 수 있는 심미적인 문제도 발생된다. 본 연구에서는 부식억제제가 상수도관의 부식도, 수돗물 중의 철 및 동의 용출 농도에 어떠한 영향을 미치는지에 대해서 평가하였다. 부식저감 효과는 인산염계 부식억제제와 큰 관련성이 있었다. 부식반응은 물과 관의 표면에서 이루어지는 일련의 전기화학적인 반응임을 고려하면 철의 용출농도와 부식도는 양(+)의 상관관계에 있다.

• 대한치과기공학회지
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• 제35권1호
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• pp.1-17
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• 2013

Purpose: This study was to assess the extents of the release of metals from the non-precious alloys used for dental casting by measuring the differences in the extents of the release of metals by types of alloys, pH level and elapsed time. Methods: Uniform-sized specimens(10 each) were prepared according to the Medical Device Standard of the Korea Food and Drug Administration(2010) and International Standard Organization(ISO22674, 2006), using four types of alloys(one type of Ni-Cr and one type of Co-Cr used for fixed prosthesis, and one type of Ni-Cr and one type of Co-Cr used for removable prosthesis). A total of 12 metal-release tests were performed at one-day, three-day, and two-week intervals, for up to 20 weeks. The metal ions were quantified using an Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: The results showed that the extent of corrosion was higher in the ascending order of Jdium-$100^{(R)}$, Bellabond-$Plus^{(R)}$, Starloy-$C^{(R)}$, and Biosil-$F^{(R)}$. The lower the pH and the longer the elapsed time were, the greater the increase in metal corrosion. At pH 2.4, the release of Ni from Jdium-$100^{(R)}$, a Ni-Cr alloy, was up to 15 times greater than the release of Co from the Co-Cr alloy from two weeks over time, indicating that the Ni-Cr alloy is more susceptible to corrosion than the Co-Cr alloy. Conclusion: It is recommended that Co-Cr alloy, which is highly resistant to corrosion, be used for making dental prosthesis with a non-precious alloy for dental casting, and that non-precious alloy prosthesis be designed in such a way as to minimize the area of its oral exposure. For patients with non-precious alloy prostheses, a test of the presence or absence of periodontal tissue inflammation or allergic reaction around the prosthesis should be performed via regular examination, and education on the good management of the prosthesis is needed.

• 환경위생공학
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• 제14권2호
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• pp.75-83
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• 1999

In this research, the has been speculation about effects of pH, alkalinity, and chloride, each of which are major factors in water for the corrosion of copper pipes frequently used as the distribution system throughout the world. It is believed that these factors release a corrosion by-product. The results show the following that the first, for each water sample of pH 7, 8 and 9, various concentrations of alkalinity at 10, 50, 100, 150 mg/L was tested. It was found that conditions of higher pH led to decreased concentrations of copper by-product. For each pH, higher alkalinity produced higher concentrations of copper by-product. the second, higher chloride concentrations led to decreased concentrations of copper by-product. Apparently this was due to the Nantokite(CuCl) formation on the inner walls of the copper pipes with the passage of time. The third, when 25, 50mg/L of chloride were added, the average decreasing rate of copper release concentration was 45.7, 66.7%, respectively.

• 한국표면공학회지
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• 제50권5호
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• pp.360-365
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• 2017

In this study, ion release and biocompatibility of sintered Ni-Cr-Ti alloy for dental prosthodontics have been researched by corrosion and cell culture test. The microstructures of the alloys were observed by optical microscope, and corrosion behavior was investigated using potentiostat (Model PARSTAT 2273, EG&G, USA). Cell culture was carried out using hGf cell in DMEM (Welgene Inc., South Korea) supplemented with 10% fetal bovine serum (FBS) (Welgene Inc., South Korea) and antibiotic antimycotic solution (Welgene Inc., South Korea). After corrosion and cell culture test, surface morphologies were observed by field-emission scanning electron microscopy. For wettability behaviors, contact angles were measured by wettability test. As the content of Ti increased, the number of pit decreased and the corrosion resistance was improved from anodic polarization test, also, polarization resistance of samples containing Ti remarkably improved as compared with the alloy not containing Ti. The sintered alloy showed a low contact angle due to the pores formed on the surface. The addition of Ti element showed that the cell survival rate was better than that of the control group.

• Nuclear Engineering and Technology
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• 제21권4호
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• pp.302-307
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• 1989

방사성폐기물 저장용기에 생긴 결함으로부터의 핵종유출을 분석하였다. 결함은 부식이나 균열으로부터 기인하며 저장용기의 재질이나 부식 부산물층을 관통하게 된다. 본 연구는 결함을 통한 핵종의 이동을 다루었으며 결함이 생기게 되는 방법에 관해서는 고려하지 않았다. 다수의 작은 결함으로부터의 핵종유출이 중요하며 저장용기가 없다고 가정한 폐기물고화체로부터의 핵종유출과 거의 비슷함을 보여준다. 비록 부분적으로 파손된 저장용기일지라도 핵종유출에 대하여서 장기간에 걸쳐 중요한 방벽의 역할을 하지만, 작은 결함의 수가 많아지면 방벽으로서의 효과가 줄어들게 된다.