• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.160-160
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• 2017

Commercially pure titanium (Cp-Ti) and Ti alloys (typically Ti-6Al-4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally. Ti and its alloys are not bioactive. Therefore, they do not chemically bond to the bone, whereas they physically bond with bone tissue. The electrochemical deposition process provides an effective surface for biocompatibility because large surface area can be served to cell proliferation. Plasma electrolyte oxidation (PEO) enables control in the chemical composition, porous structure, and thickness of the TiO2 layer on Ti surface. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation, and is also the most abundant trace element in bone. The objective of this work was to study on electrochemical behaviors of PEO-treated Ti-6Al-4V Alloy in solution containing Zn and Si ions. The morphology, the chemical composition, and the microstructure analysis of the sample were examined using FE-SEM, EDS, and XRD. The potentiodynamic polarization and AC impedance tests for corrosion behaviors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat. The promising results successfully demonstrated the immense potential of Si/Zn-TiO2 coatings in dental and biomaterials applications.

• Journal of Advanced Marine Engineering and Technology
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• 제37권8호
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• pp.877-885
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• 2013

선박 기관실의 해수 배관은 염소이온 농도와 전기 전도성이 높은 해수가 빠른 속도로 유동하는 환경에 놓여 있게 된다. 따라서 부식성이 강한 염소 이온으로 인해 배관 내부에 국부 부식이 발생하여 해수가 누설되는 경우가 종종 발생하고 있다. 그래서 해수 배관의 누설 부위에 대해 일반적으로 선박 내에서 여러 가지 피복아크용접봉을 사용하여 교류 아크용접기로 보수용접을 한다. 본 연구에서는 해수파이프 등에 E4301, E4311, E4313 및 E4316과 같은 피복아크용접봉으로 용접한 경우, 용접부위에 대해 영역별로 내식성 차이를 전기화학적 방법으로 비교 분석하고, 각각의 용접부위에 대한 미세조직 관찰 및 미소 비커스 경도를 측정하였다. E4313의 용접봉을 사용한 용접부가 다른 용접봉을 사용한 용접부에 비해 가장 낮은 경도 값을 나타내었으나 내식성은 가장 우수하게 나타나고 있다. 그리고 용접봉의 종류에 관계없이 용접부는 모재보다 상대적으로 내식성이 더 우수하였고, 경도도 더 높은 값을 나타내었다.

• Journal of Electrochemical Science and Technology
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• 제9권1호
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• pp.9-19
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• 2018

The anodic behavior of aluminum (Al) foils with varying purity, capacitance, and withstand voltage in organic electrolytes was examined for EDLC. The results of cyclic voltammetry (CV) and chronoamperometry (CA) experiments showed that the electrochemical stability improves when Al foil has higher purity, lower capacitance, and higher withstand voltage. To improve the electrochemical stability of EDLC current collectors made of low-purity foil (99.4% Al foil), the foil was modified by chemical etching to reduce its capacitance to $60{\mu}F/cm^2$ and forming to have withstand a voltage of 3 Vf. EDLC cells using the modified Al foil as a current collector were made to 2.7 V with 360 F, and a constant voltage load test was subsequently performed for 2500 hours at high temperature under a rated voltage of 2.7 V. The reliability and stability of the EDLC cell improved when the modified Al foil was used as a current collector. To understand the deterioration process of the Al current collector, standard cells made of conventional Al foil under a constant voltage load test were disassembled, and the surface changes of the foil were measured every 500 hours. The Al foil became increasingly corroded, causing the adhesion between the AC coating layer and the Al foil to weaken, and it was confirmed that partial AC coating layer peeling occurred.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.78-78
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• 2017

Pure Titanium and alloy have been widely used in dental implants and orthopedics due to their excellent mechanical properties, biocompatibility and corrosion resistance. However, due to the biologically inactive nature of Ti metal implants, it cannot bind to the living bone immediately after transplantation into the body. In order to improve the bone bonding ability of titanium implants, many attempts have been made to alter the structure, composition and chemical properties of titanium surfaces, including the deposition of bioactive coatings. The PEO method has the advantages of short experiment time and low cost. These advantages have attracted attention recently. Recently, many metal ions such as silicon, magnesium, zinc, strontium, and manganese have received attention in this field due to their impact on bone regeneration. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation and promotes bone metabolism and growth. Manganese (Mn) is an essential trace metal found in all tissues and is required for normal amino acid, lipid, protein and carbohydrate metabolism. The objective of this work was research on the corrosion behavior of Si, Zn and Mn-doped hydroxyapatite on the PEO-treated surface. Anodized alloys was prepared at 270V~300V voltage in the solution containig Zn, Si, and Mn ions. Ion release test was carried out using potentidynamic and AC impedance method in 0.9% NaCl solution. The surface characteristics of PEO treated Ti-6Al-4V alloy were investigated using XRD, FE-SEM, AFM and EDS.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.155-160
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• 2002

Metal matrix composites had generated a lot of interest in recent times because of significant in specific properties. It was also highlighted as the materials of frontier industry because strength, heat-resistant, corrosion-resistant, wear-resistant were superiored. In this study the strength properties of $Al_{18}B_4O_{33}/AC4CH$ were represented mixing the binder of $Al_2O_3$ and $TiO_2$. It was also fabricated by squeeze casting. $Al_{18}B_4O_{33}/AC4CH$ was fabricated at the melt temperature of $760^{\circ}C$ the perform temperature of $700^{\circ}C$ and mold temperature of $200^{\circ}C$ under the pressure of 83.4MPa and observed SEM. Fatigue crack growth rate tests on compact tension specimen(half-size) of thickness 12.5mm were conducted by using sinusoidal waveform. Compact tension specimens(half-size) were used and fatigue crack growth rate da/dN and stress intensity factor range ${\Delta}K$ were analyzed concerning to the R value of 0.1 and 0.05. In order to find out the value of ${\Delta}K$, load amplitude constant method was applied by the standard fatigue testing method describes in ASTM E647-95a. As the results of this study, Fatigue crack growth rate increased with in creasing the load ratio, Consequently, At equivalent stress intensity factors, the fatigue crack growth rates in MMC were faster than those of AC4CH alloy. then the fatigue life and the fatigue crack growth rate was investigated using scanning election microscopy(SEM)

• 공업화학
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• 제9권4호
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• pp.463-468
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• 1998

알루미늄의 부식에 있어서 HCI 용액내에 황산을 첨가하는 경우 황산이온의 화학적 흡착에 의한 부식억제 효과가 나타나며, CV (cyclic voltammetry) 실험결과 황산이온은 핏트내부에 보호성 산화피막을 생성함으로서 에치핏트가 핏트내부와 알루미늄 표면에 함께 생성되어 핏트의 밀도가 증가하였다. 알루미늄 교류에칭시에 핏트분포는 황산이온의 농도와 환원전류량에 의하여 크게 영향을 받으며, 환원전류인가시 $0.8mC/cm^2$ 이하의 전하량에서 핏트내부에 생성된 산화피막은 황산이온 농도의 증가에 따라 핏트발생에 대한 저항성이 중가하였으나, $0.8mC/cm^2$ 이상에서는 산화피막내에 국부적인 구조변화가 발생하며 황산이온 농도에 관계없이 산화피막의 파괴가 빠르게 진행되었다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.37-40
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• 2007

Although masonry buildings fell into disfavour in the 1990's because of factors such ac bricklayers' high labor costs, bad reputation of poorly constructed masonry, masonry face wall is still preferred in korea as well as in other countries for its decorative value. Recently may problems with masonry face wall with opening have been reported, including cracks, deflection, swelling and even wall collapse in old masonry buildings, that mainly induced from the corrosion of connecting materials. So, it is necessary to develop the effective and uncorrosion connector. Therefore, this study aims to investigate the structural performance of masonry face walls with opening constructed by new connectors, spiral stainless anchors and to provide basic data for the field application of this method. The specimen reinforced bed joint has maximum load and displacement any other specimens.

• 전력전자학회논문지
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• 제20권3호
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• pp.209-213
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• 2015

With the increasing popularity of renewable generation systems and the advancement of power electronics, DC distribution systems have recently received considerable research attention. DC distribution has numerous advantages, including reliability, power quality, and efficiency. Owing to these advantages, DC distribution has been applied to data centers and power quality-sensitive electronic load conditions. Because grounding electrodes in DC are much more susceptible to corrosion than in AC, the IT system defined in IEC Standard 60364 may be a good candidate for an earthing method for DC distribution systems. In addition, IEC Standard 61557 specifies the requirements for insulation monitoring devices (IMD) for protection of the IT system, which continuously monitors the insulation resistances between the power lines and the earth. This paper discusses the development and evaluation of IMD to promote the reliability of distribution systems and increase safety of humans and facilities.

• International Journal of Precision Engineering and Manufacturing
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• 제6권3호
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• pp.56-59
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• 2005

Aluminum alloy casting is gaining increased acceptance in automotive and electronic industries and especially, squeeze casting is the most efficient method of mass manufacturing of such parts. In this study, the microstructures and mechanical properties of Al-7.0Si-0.4Mg(AC4C) alloy fabricated by squeeze casting process for development of fuel system parts (fuel rail) are investigated. The microstructure of squeeze cast specimen was composed of eutectic structure aluminum solid solution and $Mg_2Si$ precipitates. The tensile strength of as-solid solution treatment Al-7.0Si-0.4Mg alloy was 298.5MPa. It was found that Al-7.0Si-0.4Mg alloy had good corrosion resistance in electrochemical polarization test.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.221-222
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• 2009

AZ31 마그네슘 합금에 AC 전류를 인가하여 MAO(micro-arc oxidation) process로 양극산화 할 때 알카리 전해액에 첨가되는 sodium silicate(Na2SiO3)의 농도에 따라 형성되는 양극 피막의 구조와 부식특성을 평가하였다. 전해질의 조성은 10g/1 KOH와 4g/1 KF 혼합 전해액에 sodium silicate를 (5, 10, 20, 40, 80)g/1로 달리하여 첨가한 후 $40mA/cm^2$의 전류밀도로 20분간 MAO 처리한 후 양극피막의 조직을 SEM, XRD, EPMA를 이용하여 분석하였고 동전위 분극시험으로 부식 거동을 평가하였으며 micro-vickers 경도계를 이용하여 단면의 경도를 측정하였다.