• Corrosion Science and Technology
• /
• 제18권6호
• /
• pp.228-231
• /
• 2019

Aluminum and its alloys have been widely used in various fields because of low weight, high strength, good conductivity, and low price. It is well known that aluminum alloys that cause natural oxide film can inhibit corrosion in wet, salty environments. However, these oxides are so thin that corrosion occurs in a variety of environments. To prevent this problem, an electrochemical anodizing technique was applied to the aluminum alloy surface to form a thick layer of oxide and a unique oxide shape, such as a hierarchical pore structure simultaneously combining large and small pores. The shape of the structures was implemented using stepwise anodization voltages such as 40 V for mild anodizing and 80 V for hard anodizing, respectively. To maximize water repellency, it is crucial to the role of surface structures shape. And a hydrophobic thin film was coated by 1H, 1H, 2H, 2H-Perfluorodecyltrichlorosilane (FDTS) to minimize surface energy of the structure surface. Thus, such nanoengineered superhydrophobic surface exhibited a high water contact angle and excellent corrosion resistance such as low corrosion current density and inhibition efficiency.

• 상하수도학회지
• /
• 제32권2호
• /
• pp.183-192
• /
• 2018

Applicability of corrosion inhibitor was evaluated using pilot scale water distribution pipe simulator. Calcium hydroxide was used as corrosion inhibitor and the corrosion indices of the water were investigated. Corrosion indices, Langelier saturation index (LI) increased by 0.8 and calcium carbonate precipitation potential (CCPP) increased by 9.8 mg/L. This indicated that corrosivity of water decreased by corrosion inhibitor and the effects lasted for 18 days. Optimum calcium hydroxide dose was found to be 3~5 mg/L for corrosion inhibition. We suggest that monitoring of CCPP as well as LI need to be conducted to control corrosivity of water.

• Corrosion Science and Technology
• /
• 제20권5호
• /
• pp.256-265
• /
• 2021

Titanium is applied in various industries due to its valuable properties and abundant reserves. Generally, if a highly uniform oxide structure and a high-density oxide film is formed on the surface through anodization treatment, the utility value such as color appearance and corrosion inhibition efficiency is further increased. The objective of this study was to determine improvement of water-repellent property by controlling titanium oxide parameters such as pore size and inter-pore distance to improve corrosion resistance. Oxide film structures of different shapes were prepared by controlling the anodization processing time and voltage. These oxide structures were then analyzed using a Field Emission Scanning Electron Microscope (FE-SEM). Afterwards, a Self-Assembled Monolayer (SAM) coating was performed for the oxide structure. The contact angle was measured to determine the relationship between the shape of the oxide film and the water-repellency. The smaller the solid fraction of the surface, the higher the water-repellent effect. The surface with excellent hydrophobic properties showed improved corrosion resistance. Such water-repellent surface has various applications. It is not only useful for corrosion prevention, but also useful for self-cleaning. In addition, a hydrophobic titanium may open up a new world of biomaterials to remove bacteria from the surface.

• 보존과학회지
• /
• 제34권4호
• /
• pp.259-271
• /
• 2018

Outdoor copper alloy is exposed to the atmospheric environment, accelerating corrosion progress compared with indoor copper alloy. In order to prevent corrosion, the outdoor copper alloy is coated with wax to block external corrosion factors. However, corrosion of the inside of the coating film is highly likely to continue without the internal corrosion prevention treatment. B.T.A, which is used as a copper alloy water-soluble corrosion inhibitor, has a high possibility of being harmful to the human body and is mainly used to treat excavated artifacts. This study had selected the water-soluble corrosion inhibitor, which was easier to use than the existing wax and B.T.A being used in corrosion inhibition treatment for outdoor copper alloy. A comparative study was conducted on B.T.A, which is a water-soluble corrosion inhibitor used on excavated artifacts, and $VCI^{(R)}$, $Rus^{(R)}$, and L-cys, an amino acid corrosion inhibitor, used for tin bronze test pieces. The experimental method was conducted for a certain period of time with the salt, acid, and air pollution affecting the corrosion of outdoor copper alloy. Based on experiment results, it was concluded that the best water - soluble copper alloy corrosion inhibitor in the atmospheric environment is $VCI^{(R)}$. and it could be considered to be applied in replacement of B.T.A due to its low harmfulness. In addition, $VCI^{(R)}$ is judged to serve as a corrosion inhibitor for outdoor copper alloy because it showed the best result even in the outdoor exposure test which is a real atmospheric environment.

• 대한화학회지
• /
• 제53권5호
• /
• pp.485-490
• /
• 2009

0.1 M 중탄산소듐 용액에서 납전극부식에 대한 로소니아, 감초뿌리 및 카로브 추출물수용액의 부식방지작용에 대한것을 정전류극성방법을 사용해 연구하였다. 이들 물질들의 부식방지작용을 지적해주는 것으로 이들 물질들이 존재할 때 부식속도가 감소하는 것이 발견되었다. 부식방지효율은 추출물농도가 증가하면 증가한다. 이들 추출물의 부식방지작용은 납표면에 이들 추출물이 흡착되어 물질 및 하전이동의 장벽을 만들어 나타내는 것으로 설명되었다. 이들 추출물의 납표면에 흡착은 자발적으로 일어나며, Freundlich 등온흡착을 따르는 것으로 발견되었다. 또한, 변전위양극분극법을 사용해 이들 추출물은 염소를 포함한 용액에서 납의 움푹패이게 하는 부식으로부터 잘 보호해주는 것이 발견되었다.

• Journal of Electrochemical Science and Technology
• /
• 제9권3호
• /
• pp.238-249
• /
• 2018

The impact of methanol extract of Chaenomeles sinensis (C. sinensis) leaves on acid corrosion of low carbon steel was assessed by gravimetric and electrochemical methods. Phytochemical characterization by total phenolic content (TPC), and total flavonoids content (TFC) of the extract was performed. The TPC and TFC concentrations were identified as 193.50 and 40.55 mg/g. Efficiency increased remarkably in the presence of inhibitor and found as concentration dependent. A maximum inhibition efficiency of 93.19% was achieved using 2000 ppm of the C. sinensis inhibitor. Impedance and surface morphology analysis by SEM and AFM revealed that the anticorrosive activity results from the protective film of phytochemical components of C. sinensis extract adsorbed on the metal surface.

• 한국응용과학기술학회지
• /
• 제28권2호
• /
• pp.140-145
• /
• 2011

Cationic gemini-surfactant, namely 1,4-butane-bis(N-alkanoyloxyethyl-N,Ndimethyl)-diammonium bromide was synthesized and their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. The synthesized product was confirmed by FT-IR and $^1H-NMR$ spectroscopy. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was $4.1{\times}10^{-5}{\sim}5.4{\times}10^{-5}$ mol/L. The Krafft point of the these surfactants were <0~$10.7^{\circ}C$. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, 1,4-butane-bis(N-lauroyloxyethyl-N,N-dimethyl)- diammonium bromide, CGL 14-4-14 has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.

• 한국응용과학기술학회지
• /
• 제31권1호
• /
• pp.1-6
• /
• 2014

Gemini type of cationic surfactant, namely ${\alpha},{\omega}$-alkane-bis(N-lauroyloxyethyl-N,N-dimethyl)-diammonium bromide was synthesized and confirmed by FT-IR and $^1H$-NMR spectroscopy. Their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was $4.01{\times}10^{-5}{\sim}4.99{\times}10^{-5}mol/L$. The Krafft point of the these surfactants were < $0^{\circ}C$. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, ${\alpha},{\omega}$-alkane-bis(N-lauroyloxyethyl-N,N-dimethyl)-diammonium bromide has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.

• 대한화학회지
• /
• 제53권6호
• /
• pp.671-676
• /
• 2009

밀도 함수이론을 사용해 철 부식 방지제로써 메톨(N-메틸-p-아미노페놀 설페이트)에 대한 기하학적 및 전자구조에 대한 연구가 처음으로 기술되었다. B3LYP/6-31G+(d,p) 기저세트를 사용해 기상 및 액상에서 HOMO, LUMO, 에너지갭 (${\Delta}E$), 멀리칸하전 ($q_M$), 자연원자하전 ($q_n$)과 같은 양자화학적 변수들이 계산되었다. 부식방지메카니즘을 이해하기 위해 부식방지효율과 양자화학적 변수들간의 연관성이 논의되었다.

• 한국표면공학회지
• /
• 제36권3호
• /
• pp.277-283
• /
• 2003

Electrochemical techniques were used to study the surface treatment for improving the pitting corrosion resistance of 304L stainless steel by inhibitors in chloride medium. Sodium molybdate (in concentration range : 0.005-80 g/l) , sodium nitrite (in concentration range : 0.001-50 g/l) and their mixture were used for this study. It was found that, molybdate and nitrite were good passivators for 304L stainless steel, but molybdate was not able to prohibit the pitting ; nitrite prevented pitting corrosion of 304L stainless steel only at the concentration more than 25 g/l. The relationship between pitting potentials and concentrations of inhibitors in the logarithm expression obeyed the linear function. It was found that the surface treatment by mixture of two inhibitors enables stainless steel to have increased the corrosion resistance , the pitting corrosion of 304L stainless steel was completely prohibited by the mixtures of molybdate and nitrite in ratio min, with $m\;\geq\;3\;and\;n\;\geq\;10$. The interesting cases on electrochemical measurement of threshold of inhibitors concentration combination for optimum surface treatment were described.