• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2005년도 춘계 학술기술논문발표대회 논문집
• /
• pp.211-214
• /
• 2005

Recently, Deterioration of the concrete sewer concrete structures by biochemical corrosion has been issued and a development of the inhibition system of corrosion that has been demanded. The sulfuric acid may react with the hardened cement paste and originate expansive products which can induce swelling and breakless of concrete. Also, a sulphuric acid reacts with calcium hydroxide to from $CaSO_4\;\cdot\;2H_2O$. This reaction accounts for consumption of the calcium hydroxide present in hardened cement paste. In this study, To present from biochemical corrosion of the sewer repair mortar that was spread with liquefied antibiotic and then its experimental properties were experimentally investigated and to estimate the effect of absorbed condition of restorative mortar, the number of coating times and coating contents with antibiotic on the durability properties of restorative mortar spread with antibiotics. Also, testing items such as carbonation depth, choloride ion penetration depth and chemical resistance was tested to estimate the durability properties in third study. In results, the novellus bacillus inhabiting in sewer concrete structures was restrained by antibiotics developed in this study. And carbonation depth, choloride ion penetration depth and chemical resistance of restorative mortar spread with antibiotics was superior to that of plain mortar.

• 한국표면공학회지
• /
• 제44권3호
• /
• pp.82-88
• /
• 2011

A uniform chromium-free conversion coating treated with an alkaline phosphate- permanganate solution was formed on the AZ 31 magnesium alloy. The effect of acid pickling on the morphology and on the corrosion resistance of the alkaline phosphate-permanganate conversion coating was investigated. The chemical composition and phase structure of conversion coating layer were determined via optical microscopy, SEM, EDS, XPS and XRD. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to $2.4\;{\mu}m$. The alkaline phosphate-permanganate conversion coating was mainly composed of elements Mg, O, P, Al and Mn. The conversion-coated layers were stable compounds of magnesium oxide and spinel ($MgAl_2O_4$). These compounds were excellent inhibitors to corrosion. The electrochemical corrosion behaviors of coatings in 3.5 wt.% NaCl solutions were evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization technique. EIS results showed a polarization resistance of $0.1\;k{\Omega}$ for the untreated Mg and $16\;k{\Omega}$ for the alkaline phosphate-permanganate conversion treatment sample, giving an improvement of about 160 times. The results of the electrochemical measurements demonstrated that the corrosion resistance of the AZ 31 magnesium alloy was improved by the alkaline phosphate-permanganate conversion treatment.

• Journal of Electrochemical Science and Technology
• /
• 제13권2호
• /
• pp.237-253
• /
• 2022

The methyl 2-(1,3-dithietan -2- ylidene)-3-oxobutanoate (MDYO) and 2-(1,3-dithietan-2-ylidene) cyclohexane -1,3-dione (DYCD) were synthesized and tested at various concentrations as corrosion inhibitors for 316L stainless steel in 1 M HCl using weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface analysis techniques (SEM / EDX and Raman spectroscopy) and Functional Density Theory (DFT) was also used to calculate quantum parameters. The obtained results indicated that the inhibition efficiency of MDYO and DYCD increases with their concentration, and the highest value of corrosion inhibition efficiency was determined in the range of concentrations investigated (0.01 × 10^-3 - 10^-3 M). Polarization curves (Tafel extrapolation) showed that both compounds act as mixed-type inhibitors in 1M HCl solutions. Electrochemical impedance spectra (Nyquist plots) are characterized by a capacitive loop observed at high frequencies, and another small inductive loop near low frequencies. The thermodynamic data of adsorption of the two compounds on the stainless steel surface and the activation energies were determined and then discussed. Analysis of experimental results shows that MDYO and DYCD inhibitors adsorb to the metal surface according to the Langmuir model and the mechanism of adsorption of both inhibitors involves physisorption. SEM-EDX results confirm the existence of an inhibitor protective film on the stainless steel surface. The results derived from theoretical calculations supported the experimental observation.

• 한국응용과학기술학회지
• /
• 제38권1호
• /
• pp.19-28
• /
• 2021

부식은 환경과의 반응에 의한 금속의 열화이다. 이는 완전히 제거하기가 어렵다. 부식은 보호장벽이 파괴 된 후 빠르게 진행되며 매트릭스로의 금속 양이온 확산, 산화물 형성과 국소 pH 변화 같은 금속 표면과 국소 환경의 조성과 특성을 변경하는 여러 반응이 일어난다. 강과 철의 부식에 대한 연구는 이론적, 실제적 관심사이며 상당한 관심을 받고 있다. 산업용 산세척, 산 스케일 제거, 세척 및 유정 산성화에 널리 사용되는 산 용액은 금속 재료에 대한 부식 공격을 억제하기 위해 부식 억제제를 사용해야한다. 녹을 물리적으로 제거하려면 고가의 특수 장비가 필요하며 이를 화학적으로 제거하면 부식을 유발하거나 금속의 수명을 단축 할 수 있다. 본 연구에서는 퍼머 환원제와 킬레이트 개념을 적용하여 화장품 및 식품소재를 이용한 친환경 녹 세정제를 개발하였고 산업 및 온수 관, 각종 산업 기기의 녹을 제거하기 위해 적용하여 보았다. 그 결과, 녹 세정제는 기존 처리 방식에 비해 녹을 더 효과적이고 안전하게 제거하는 것으로 나타났다. 동일한 시간에서 녹 제거 효율은 기존의 방법보다 공업용 배관의 경우 1.75 ~ 2.5 배, 보일러 온수용 배관의 경우 1.56 ~ 2.2 배 우수하였다.

• 한국과학예술포럼
• /
• 제30권
• /
• pp.251-261
• /
• 2017

금속은 우리 인류 문화 발전에 많은 영향을 준 재료이며, 과거에서부터 현재까지 우리 생활에 밀접한 연관이 있는 재료이다. 선사시대부터 사용해온 금속의 종류는 다양하며 우리나라의 출토 금속 유물 중 철기유물이 가장 큰 비중을 차지하고 있다. 출토 유물에서 전승 유물에 이르기까지 철기 유물들의 존재를 가장 크게 위협하는 것이 부식 진행 과정이며, 부식된 산화물을 제거하기 위해서는 현재 물리적인 제거 방법이 가장 많이 사용되고 있다. 본 논문은 부식 산화물을 제거하는 작업에 대한 내용으로 철기 유물 자체의 모재는 보호하면서 부식 산화물만을 처리하는 화학적 부식 산화물 제거제에 대하여 연구하고자 하였다. 철기 유물의 부식 산화물에 대한 보다 안전하고 효과적인 제거를 위해, 새로운 산성, 알칼리성, 중성의 산화물 제거제를 제조하고, 이의 조성을 다양하게 변화하면서 철기 유물의 부식 산화물 제거 가능성과 최적화된 조성을 찾는 것에 목표를 두고 실행하였으며 근대 유물에 적용하여 그 가능성까지를 검토하였다. 연구결과는 다음과 같다. 첫째, 산성 처리 용액의 경우 철 시편 표면에 산화된 부식물은 일부만이 제거되는 결과를 나타내었다. 둘째, 알칼리성과 중성 처리 용액의 경우 검은색의 부식물이 남은 상태였으나 이는 처리 시간과 처리 용액의 양을 증가시키면 이들도 제거되는 결과를 나타내었다. 셋째, 이 세 종류 용액은 처리 시에 모두 모재 자체에 손상을 주지 않았으며 용액의 농도와 처리 시간의 조절만으로도 유물에 따른 상황 대처가 가능하여 모재나 안정화 부식층을 보호하면서 불안정한 산화물층만을 제거할 수 있는 결과를 나타내었다.

• 대한화학회지
• /
• 제55권3호
• /
• pp.364-372
• /
• 2011

다양한 억제제의 농도, 온도, 유속에서 중량 분석과 변전위 분극법을 이용하여 0.25 M 황산 용액상에 있는 연강철에 대한 imatinib mesylate (IMT)의 부식 억제를 연구하였다. 억제제의 농도가 증가함에 따라 억제 효과가 증가한다는 결과를 얻었다. 연강철 표면 위의 흡착 과정은 Langmuir 흡착 등온선을 따른다. 얻어진 흡착 깁스 자유 에너지의 값은 연강철 위의 IMT의 흡착 과정이 화학흡착이라는 것을 보여준다. 열역학 변수들이 계산되고, 논의되었다. IMT의 HOMO와 LUMO의 전자궤도 밀도 분포는 억제 메커니즘을 논의하는데 이용되었다. FT-IR 분광학과 SEM 이미지는 필름에 흡착된 표면을 분석하기 위해 사용되었다.

• 한국표면공학회지
• /
• 제43권2호
• /
• pp.73-79
• /
• 2010

A chromium-free conversion coating for AZ31 magnesium alloy has been obtained by using a permanganatephosphate solution, which has been developed with acid pickling. Examination have been carried out on the conversion coatings for morphology, composition and corrosion resistance. The morphology of the conversion-coated layer was observed using optical microscope and SEM. It was shown that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to 2.7 ${\mu}m$. The chemical composition of conversion coating was mainly consisted of Mg, O, P, K, Al and Mn by EDS analysis. It was found that the corrosion resistance of the AZ31 magnesium alloy has been improved by the permanganate-phosphate conversion treatment from electrochemical polarization.

• Journal of Electrochemical Science and Technology
• /
• 제13권1호
• /
• pp.138-147
• /
• 2022

The synergistic effect of 2-chloromethylbenzimidazole (2-CBI) and potassium iodide (KI) for mild steel in 1 M hydrochloric acid solution was investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that, with the addition of 100 ppm potassium iodide, the inhibition efficiecy (IE) of 100 ppm 2-CBI in 1 M hydrochloric acid had been improved from 91.14% to 96.15%. And synergistic parameter of 100 ppm 2-CBI with different amounts of potassium iodide is always greater than 1. The adsorption of potassium iodide combining with 100 ppm 2-CBI obeys to the Langmuir adsorption isotherm. Thermodynamic adsorption parameters, including ∆G⁰_ads, ∆H_a and ∆S_a of the adsorption of the combinned inhibitor, as well as the E_a of the mild steel corrosion in 1 M HCl with the combinned inhibitor, were calculated.

• Corrosion Science and Technology
• /
• 제21권2호
• /
• pp.89-99
• /
• 2022

A versatile method for performing non-cyanide electroless gold plating using thiomalic acid (TMA) as a complexing agent and 2-aminoethanethiol (AET) as a reducing agent was investigated. It was found that TMA was an excellent complexing agent for gold. It can be used in electroless gold plating baths at a neutral pH with a high solution stability, makes it a potential candidate to replace conventional toxic cyanide complex. It was found that one gold atomic ion could bind to two TMA molecules to form the [2TMA-Au⁺] complex in a solution. AET can be used as a reducing agent in electroless gold plating solutions. The highest current density was obtained at electrode rotation rate of 250 to 500 rpm based on anodic and cathodic polarization curves with the mixed potential theory. Increasing AET concentration, pH, and temperature significantly increased the anodic polarization current density and shifted the plating potential toward a more negative value. The optimal gold ion concentration to obtain the highest current density was 0.01 M. The cathodic current was higher at a lower pH and a higher temperature. The current density was inversely proportional to TMA concentration.

• Applied Microscopy
• /
• 제45권4호
• /
• pp.249-253
• /
• 2015

Microorganisms specifically groups of bacteria exhibiting physiological activities of production of acids are a major cause of concern because of their ability to induce corrosion in oil field pipelines and metal systems involved in water handling. Water Injection Stations as a means of secondary recovery from existing oil producing reservoirs, are often employed in most upstream oil and gas industries to ensure replenishment of voidage, maintenance of reservoir pressure and optimization of crude emulsion throughput. In the present study, scanning electron microscopy of macroscopic orange coloured slime formations sampled from leaking valves on the flow-lines of a Water Injection Stations of Oil India Limited revealed the presence of filamentous bacterial mats in association with diatoms. The species composition of the acidic slime formations from the sampled locations reveal the possible role of acid producing iron oxidizing bacteria (IOB) like Acidithiobacillus ferrooxidans in association with Gomphonema sp. in creating conditions for bio-corrosion.