• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.535-541
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• 1997

The effect of concentration of each solution( HCI, $H_2SO_4$ and $HNO_3$), scan rate and polished surface condition on the corrosion of AISI 304 Stainless Steel were investigated, utilizing the Method ASTM G5 - 87. It can be concluded that: 1) For the same concentration(i.e. 1N) of each solution the corrosion rate is the highest in HCI and lowest in $HNO_3$. Also, the difference of values of $i_{cirt}$ generated for each solution is significant. 2) As the concentration of the solution $H_2SO_4$ is increased (O.5N, 1N, 2N) the values of $E_{cor}$ $i_{crit}$ and $i_{p}$ are increased. 3) In case of existence of SCN ion of O.OlN, the values of iCTIt and ip generated are approximately 100 times and 1.4 times higher respectively, than in the case of non - existence of $SCN^{-}$. However the existence of $SCN^{-}$ doesn't affect the value of $E_{cor}$ and $E_{p}$. 4) The values of $i_{crit}$ and $i_{p}$ are increased due to the increase of scan rate. But the values of $E_{cor}$ and $E_{p}$ do not depend on the scan rate. 5) The $i_{p}$ value depends greatly on oxygen in the solution, but the changes in values of $E_{cor}$ $i_{crit}$ and $E_{b}$ due to the oxygen are insignificant. 6) If a component is polished using #400, #600 and #800 wet polish paper, the effect of surface condition on variations of values of $i_{crit}$ and $i_{p}$ is slightly significant.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.80-80
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• 2017

Titanium and its alloys that have a good biocompatibility, corrosion resistance, and mechanical properties such as hardness and wear resistance are widely used in dental and orthopedic implant applications. However, they do not form a chemical bond with bone tissue. Plasma electrolytic oxidation (PEO) that combines the high voltage spark and electro-chemical oxidation is a novel method to form ceramic coatings on light metals such as tita-nium and its alloys. This is an excellent re-producibility and economical, because the size and shape control of the nano-structure is relatively easy. Silicon (Si), manganese (Mn), and magne-sium (Mg) have a useful to bone. Particularly, Si has been found to be essential for normal bone, cartilage growth, and development. Mn influences regulation of bone remodeling be-cause its low content in body is connected with the rise of the concentration of calcium, phosphates and phosphatase out of cells. Pre-studies have shown that Mg plays very im-portant roles in essential for normal growth and metabolism of skeletal tissue in verte-brates and can be detected as minor constitu-ents in teeth and bone. In this study, Electrochemical behavior of plasma electrolytic oxidized films formed in solution containing Mn, Mg and Si ions were researched using various experimental in-struments. A series of Si-Mn-Mg coatings are produced on Ti dental implant using PEO, with the substitution degree, respectively, at 5 and 10%. The potentiodynamic polarization and AC impedance tests for corrosion behav-iors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to + 2000mV. Also, AC impedance was performed at frequencies anging from 10MHz to 100kHz for corrosion resistance.

• Journal of Advanced Marine Engineering and Technology
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• 제9권2호
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• pp.126-142
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• 1985

The plane bending corrosiion fatigue test for the welded metal parats was performed in the air and in the natural sea water with and without applying cathodic protection. The specimens tested were the weld of SM41 steel plates, SM58 steel plates and of SM41 to SM58, which were all prepared by submerged arc welding. The main results obtained from the experiment are summarized as follows: (1) In case with SM41 and SM58 steel plates, lower value of impact strength, higher value of hardness and more noble electrode potential were observed in the welded metal part than in the HAZ and base metal. Also the lowest hardness zone in the HAZ was observed with SM58 which was not found with SM41. In case with weld specimen of SM41 to SM58, the impact strength and the electrode potential of the welded metal part showed again the lowest and most noble value but the hardness value was located between those of SM41 and SM58 base metal. (2) In the fatigue test, the specimens tested in the air and under the cathodic protection were both cracked in a purely mechanical mode, but the specimens tested without cathodic protection were cracked by the combination of mechanical fracture and electro-chemical corrosion. (3) The corrosion fatigue limit of the welded metal parts of the specimen was increased by the cathodic protection. As the protection potential was varied down to -800 mV vs. SCE the fatigue limit was increased to the value tested in the air, and the maximum fatigue limit appeared at the -1, 000 - -1, 200 mV vs. SCE. However, as the protection potential was further decreased below -1, 200 mV vs.SCE, the fatigue limit of weld of SM58 and of SM41-SM58 joining was decreased but the limit was almost constant in the case of weld of SM41. (4) It is suggested that when designing steel ship the corrosion fatigue limit of welded metal parts should be stressed as a designing strength of the structure of steel ship in addition to the conventional basis considering simply tensile strength of steel and safety factor.

• 대한치과보철학회지
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• 제31권3호
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• pp.423-446
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• 1993

Titanium and its alloys are finding increasing use in medical devices and dental implants. The strong selling point of titanium is its resistance to the highly corrosive body fluids in which an implant must survive. This corrosion resistance is due to a tenacious passive oxide or film which exists on the metal's surface and renders it passive. Potentiodynamic polarization measurement is one of the most commonly used electro-chemical methods that have been applied to measure corrosion rates. And the potentiodynamic polarization test supplies detailed information such as open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. This study was designed to compare the corrosion resistance of the commonly used dental implant materials such as CP Ti, Ti-6A1-4V, Co-Cr-Mo alloy, and 316L stainless steel. And the effects of galvanic couples between titanium and the dental alloys were assessed for their useful-ness-as. materials for superstructure. The working electrode is the specimen , the reference electrode is a saturated calomel electrode (SCE), and the counter electrode is made of carbon. In $N_2-saturated$ 0.9% NaCl solutions, the potential scanning was performed starting from -800mV (SCE) and the scan rate was 1 mV/sec. At least three different polarization measurements were carried out for each material on separate specimen. The galvanic corrosion measurements were conducted in the zero-shunt ammeter with an implant supraconstruction surface ratio of 1:1. The contact current density was recorded over a 24-hour period. The results were as follows : 1. In potential-time curve, all specimens became increasingly more noble after immersion in the test solution and reached between -70mV and 50mV (SCE) respectively after 12 hours. 2. The Ti and Ti alloy in the saline solution were most resistant to corrosion. They showed the typical passive behavior which was exhibited over the entire experimental range. Therefore no breakdown potentials were observed. 3. Comparing the rupture potentials, Ti and Ti alloy had the high(:st value (because their break-down potentials were not observed in this study potential range ) followed by Co-Cr-Mo alloy and stainless steel (316L). So , the corrosion resistance of titanium was cecellent, Co-Cr-Mo alloy slightly inferior and stainless steel (316L) much less. 4. The contact current density sinks faster than any other galvanic couple in the case of Ti/gold alloy. 5. Ag-Pd alloy coupled with Ti yielded high current density in the early stage. Furthermore, Ti became anodic. 6. Ti/Ni-Cr alloy showed a relatively high galvanic current and a tendency to increase.

• 공업화학
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• 제19권2호
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• pp.228-235
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• 2008

니켈 표면처리 공정에서 전류밀도에 따라 니켈의 전착두께가 증가되었으며, 증가폭은 $6{\sim}10A/dm^2$에서 저전류보다 높게 나타났다. 전류밀도를 측정하기 위해 Hull-cell 분석을 수행 하였다. 최적 공정온도는 $60^{\circ}C$, pH는 3.5~4.0이었고, 전해용액 중 니켈이온의 농도는 300 g/L 이상에서 농도에 따라 전착두께가 증가되었다. 전류밀도에 따라 용액 중 니켈이온 감소 속도가 증가되었는데, 이는 음극표면에서 니켈 전착 량에 따른 전착두께의 증가를 나타낸다. 그러나 전착속도가 빠를 경우 니켈 전착 층의 치밀성은 저하되며, 표면의 상태는 불규칙하게 변화된다. 니켈이온의 전착과정이 불규칙하게 일어나 조직의 pin hole 등을 야기해 표면특성을 저하시키는 것으로 확인되었다. 광택니켈 전착 후 25 h 내식을 유지한 결과, 낮은 전류밀도를 유지하는 것이 내식특성이 우수한 것으로 나타났다. 프로그램모사 결과, 전류밀도가 높아질수록 확산 층의 두께는 증가하며, 음극표면의 농도는 낮아진다. 농도분포는 낮은 전류밀도에서 고른 분포를 나타내었으며 이는 일정한 전착두께를 예측할 수 있다. 생산성 저하를 예방하기 위해 공정시간은 크게 변화시키지 않았으며, 전류밀도와 전착두께를 변화시키면서 공정변수를 조절하였다. 본 연구의 표면분석 결과 조직특성이나 내식성 등의 표면 물성이 낮은 전류밀도를 사용할 경우에 더욱 우수한 것으로 나타났다.

• Journal of Electrochemical Science and Technology
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• 제4권2호
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• pp.57-60
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• 2013

Nickel is a good electrocatalytic metal and nickel electrodes find many applications in different electrochemical fields. The nickel plated electrodes were prepared by electro-deposition technique on mild steel surface modified with in-situ deposition of nickel titanate. The SEM images shows that the nickel plating on nickel titanate modified mild steel shows better adherence than the nickel plating on bare mild steel surfaces. The extent of polarization of the nickel plating on mild steel with nickel titanate was lower than that of nickel plating on mild steel. The incorporation of nickel titanate on mild steel surface before nickel plating enhances physical, chemical and electrochemical properties of the plating film.

• 전기학회논문지
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• 제60권3호
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• pp.680-685
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• 2011

Nowadays, in metropolitan railroad, DC feeding system is being generally applied. In order to reduce damages of electro-chemical corrosion caused by stray current and leakage current, in DC feeding system, rail is used as negative-polarity return conductor for traction load current. However, it has problem of rail potential increase and there are no adequate measures to prevent it in domestic. In this paper, we presented fundamental theory and related standards about rail potential increase. And then, we analyzed field testing data and simulated a variety of operations by using PSCAD/EMTDC as an analysis program of power system. In addition, voltage control device is suggested to prevent accidents caused by rail potential increase.

• International Journal of Railway
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• 제2권4호
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• pp.170-174
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• 2009

Super speed tube train is introduced to increase the speed of ground transportation. The super speed tube train levitates magnetically and runs in a partial vacuum tube, which can reduce the air resistance significantly. However, the strong magnetic force enough to propel the massive train can affect to the tube infrastructure. In this paper, authors have analyzed the leakage flux patterns and induced eddy current on the tube by using 3-dimensional Finite Element Method. These effects are investigated, especially by varying the materials and diameters of the tube. From the simulation results, the aluminum tube with the diameter of 3[m] is needed to be concerned because the induced eddy current produces joule heat, raises the inside temperature of the tube, and might be able to lead to electro-chemical corrosion on the tube, consequently reduce the durability.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.546-546
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• 2008

Copper (Cu) Chemical mechanical polishing (CMP) has been an essential process for Cu wifing of DRAM and NAND flash memory beyond 45nm. Copper has been employed as ideal material for interconnect and metal line due to the low resistivity and high resistant to electro-migration. Damascene process is currently used in conjunction with CMP in the fabrication of multi-level copper interconnects for advanced logic and memory devices. Cu CMP involves removal of material by the combination of chemical and mechanical action. Chemicals in slurry aid in material removal by modifying the surface film while abrasion between the particles, pad, and the modified film facilitates mechanical removal. In our research, we emphasized on the role of chemical effect of slurry on Cu CMP, especially on the effect of amine functional group on removal rate selectivity between Cu and Tantalum-nitride (TaN) film. We investigated the two different kinds of complexing agent both with amine functional group. On the one hand, Polyacrylamide as a polymer affected the stability of abrasive, viscosity of slurry and the corrosion current of copper film especially at high concentration. At higher concentration, the aggregation of abrasive particles was suppressed by the steric effect of PAM, thus showed higher fraction of small particle distribution. It also showed a fluctuation behavior of the viscosity of slurry at high shear rate due to transformation of polymer chain. Also, because of forming thick passivation layer on the surface of Cu film, the diffusion of oxidant to the Cu surface was inhibited; therefore, the corrosion current with 0.7wt% PAM was smaller than that without PAM. the polishing rate of Cu film slightly increased up to 0.3wt%, then decreased with increasing of PAM concentration. On the contrary, the polishing rate of TaN film was strongly suppressed and saturated with increasing of PAM concentration at 0.3wt%. We also studied the electrostatic interaction between abrasive particle and Cu/TaN film with different PAM concentration. On the other hand, amino-methyl-propanol (AMP) as a single molecule does not affect the stability, rheological and corrosion behavior of the slurry as the polymer PAM. The polishing behavior of TaN film and selectivity with AMP appeared the similar trend to the slurry with PAM. The polishing behavior of Cu film with AMP, however, was quite different with that of PAM. We assume this difference was originated from different compactness of surface passivation layer on the Cu film under the same concentration due to the different molecular weight of PAM and AMP.

• 대한치과보철학회지
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• 제49권1호
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• pp.65-72
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• 2011

연구 목적: 이 연구의 목적은 티타늄 지대주와 비귀금속 보철물이 접촉한 경우를 가정하여 이종 금속간 접촉에 의한 갈바닉 부식으로 인해 발생하는 표면 거칠기 변화를 비교, 평가하고자 하였다. 연구 재료 및 방법: 성분과 조성이 다른 3종의 Ni-Cr합금 (T3, Bella bond plus, Tilite)과 cp 티타늄 Grade 2를 이용하여 $13{\times}13{\times}1.5\;mm$의 크기로 시편을 각 군당 6개씩 제작하였다. 연마과정 후 절연 테이프로 직경 6 mm만을 노출시켜 potentiostat (Parastat 2273A)를 이용하여 동전위 분극 시험과 갈바닉 부식 시험을 시행하였으며, 표면 거칠기 측정기(Surftester SV-3000)를 이용하여 부식 전 후 거칠기를 평가하였다. 측정값을 paired t-test와 One-way ANOVA로 분석하였다. 결과: 티타늄과 접촉한 모든 Ni-Cr 시편의 표면 거칠기는 통계적으로 유의하게 증가하였다. 증가량은 베릴륨을 포함한 T3합금 ($0.016{\pm}.007\;{\mu}m$)이 가장 컸으며, 베릴륨을 포함하지 않은 Bella bond plus ($0.012{\pm}.003\;{\mu}m$), 티타늄을 첨가한 Tilite ($0.012{\pm}.002\;{\mu}m$)는 큰 차이를 보이지 않았다. 금속 종류에 따른 거칠기 증가는 유의한 차이를 보이지 않았다. 결론: 티타늄과 접촉한 비귀금속 합금은 갈바닉 부식에 의해 표면 거칠기가 증가하였다.