• 제목/요약/키워드: Electrochemical damage

검색결과 118건 처리시간 0.02초

산성비 환경을 모사한 수용액에서 염화물 농도에 따른 전기자동차 배터리 하우징용 재료의 전기화학적 특성 연구 (Investigation on Electrochemical Characteristics of Battery Housing Material for Electric Vehicles in Solution Simulating an Acid Rain Environment with Chloride Concentrations)

  • 신동호;김성종
    • Corrosion Science and Technology
    • /
    • 제21권2호
    • /
    • pp.147-157
    • /
    • 2022
  • Electrochemical characteristics and damage behavior of 6061-T6 aluminum alloy used as a battery housing material for electric vehicles were investigated in solution simulating the acid rain environment with chloride concentrations. Potentiodynamic polarization test was performed to analyze electrochemical characteristics. Damage behavior was analyzed through Tafel analysis, measurement of damage area, weight loss, and surface observation. Results described that corrosion current density was increased rapidly when chloride concentration excceded 600 PPM, and it was increased about 7.7 times in the case of 1000 PPM compared with 0 PPM. Potentiodynamic polarization experiment revealed that corrosion damage area and mass loss of specimen increased with chloride concentrations. When chloride concentration was further increased, the corrosion damage area extended to the entire surface. To determine damage tendency of pitting corrosion according to chloride concentration, the ratio of damage depth to width was calculated. It was found that the damage tendency decreased with chloride concentrations. Thus, 6061-T6 aluminum alloy damage becomes larger in the width direction than in the depth direction when a small amount of chloride is contained in an acid rain environment.

해수 내 캐비테이션 환경에서 동합금의 정전위법에 의한 손상 방지 기술 (Damage Protection Technology by Potentiostatic Method of Cu Alloy Under Cavitation Environment in Seawater)

  • 김성종;박재철;장석기
    • 한국표면공학회지
    • /
    • 제46권3호
    • /
    • pp.120-125
    • /
    • 2013
  • This investigation was to identify the electrochemical corrosion protection conditions to minimize the cavitation damage by generating hydrogen gas with the means of hydrogen overvoltage before the impact pressure of the cavity is transferred to the surface. The hybrid potentiostatic test method is designed to evaluate a complexed cavitation and electrochemical characteristic for ALBC3 alloy that is diverse and its broad applications fields in marine industry. The surface observation showed that neither the cavitation damage nor the electrochemical damage by the hydrogen gas generation occurred in the potential of -2.6 V under the cavitation environment. In the potentiostatic experiments under the cavitation environment, the cavities were reflected or cancelled out by the collision of the cavities with the hydrogen gas generated by the hydrogen overvoltage.

천연해수 용액에서 STS 304와 용융 알루미늄 도금된 STS 304의 캐비테이션-침식 환경 하에서의 전기화학적 특성 (Electrochemical Characteristics under Cavitation-Erosion Environment of STS 304 and Hot-Dip Aluminized STS 304 in Sea Water Solution)

  • 정상옥;김성종
    • 한국표면공학회지
    • /
    • 제49권1호
    • /
    • pp.26-31
    • /
    • 2016
  • In this paper, the characteristics of a cavitation-erosion damage behavior on the STS 304 and hot-dip aluminized STS 304 under cavitation environment in sea water solution was investigated. The electrochemical experiments were carried out by potential measurement, anodic/cathodic polarization test, Tafel analysis, and also galvanostatic experiment in current density variables for the samples. The apparatus of cavitation-electrochemical experiment was manufactured in compliance with modified ASTM G-32 standard, with the conditions of sea water temperature of $25^{\circ}C$ and the measurement, amplitude of $30{\mu}m$. The damage behavior was analyzed by an observation of surface mophologies and a measurement of damage depth by a scanning electron microscope(SEM) and a 3D microscope, respectively, after electrochemical test. After polarization experiment under cavitation environment, much higher damage depths for the hot-dip aluminized STS 304 were observed comparing to the untreated STS 304. In addition, higher corrosion current density in hot-dip aluminized STS 304 presented than that of untreated STS 304 as a result of Tafel analysis.

전기화학기법에 의한 슈퍼 오스테나이트 스테인리스강의 열화손상 평가 (An Evaluation of Degraded Damage for Superaustenitic Stainless Steel by Electrochemical Polarization Technique)

  • 권일현;이송인;백승세;이종기;;유효선
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2001년도 추계학술대회논문집A
    • /
    • pp.143-148
    • /
    • 2001
  • This research was undertaken to clarify effects of thermal aging on electrochemical and mechanical properties of superaustenitic stainless steel. The steel was artificially aged at $300{\sim}650^{\circ}C$ for $240{\sim}10,000hrs$. and investigated at $-196{\sim}650^{\circ}C$ using small punch(SP) test. Also, the change in electrochemical properties caused by effects of thermal aging was investigated using electrochemical anodic polarization test in a KOH electrolyte. Carbides and ${\eta}-phase(Fe_2Mo)$ precipitated in the grain bounderies seem to deteriorate the mechanical properties by decreasing cohesive strength in the grain bounderies and promote the current density observed in electrochemical polarization curves. The electrochemical and mechanical properties of superaustenitic stainless steel was drastically decreased in the specimen aged at $650^{\circ}C$.

  • PDF

전기화학적 양극분극시험에 의한 고온 설비부재의 열화손상 평가 (Degradation Damage Evaluation of High Temperature Structural Components by Electrochemical Anodic Polarization Test)

  • 유호선;송문상;송기욱;류대영
    • 대한기계학회논문집A
    • /
    • 제24권6호
    • /
    • pp.1398-1407
    • /
    • 2000
  • The structural steels of power plant show the decrease of mechanical properties due to degradation such as temper embrittlement, creep damage and softening during long-term operation at high temper ature. The typical causes of material degradation damage are the creation and coarsening of carbides(M23C6, M6C) and the segregation of impurities(P, Sb and Sn) to grain boundary. It is also well known that material degradation induces the cleavage fracture and increases the ductile-brittle transition temperature of steels. So, it is very important to evaluate degradation damage to secure the reliable and efficient service condition and to prevent brittle failure in service. However, it would not be appropriate to sample a large test piece from in-service components. Therefore, it is necessary to develop a couple of new approaches to the non-destructive estimation technique which may be applicable to assessing the material degradation of the components with not to influence their essential strength. The purpose of this study is to propose and establish a new electrochemical technique for non-destructive evaluation of material degradation damage for Cr-Mo steels which is widely used in the high temperature structural components. And the electrochemical anodic polarization test results are compared with those of semi-nondestructive SP test.

슈퍼 오스테나이트 스테인리스강의 열화손상에 대한 비파괴적 평가 (An Nondestructive Evaluation of Degraded Damage for Superaustenitic Stainless Steel)

  • 권일현;백승세;;유효선
    • 대한기계학회논문집A
    • /
    • 제26권7호
    • /
    • pp.1332-1339
    • /
    • 2002
  • This research was undertaken to clarify effects of thermal aging on electrochemical and mechanical properties of superaustenitic stainless steel and to detect the material degradation nondestructively. The steel was artificially aged at $300{\sim}650^{\circ}C$ for $240{\sim}10,000h$ and the mechanical properties were investigated at $-196{\sim}650^{\circ}C$ using small punch(SP) test. Also, the change in electrochemical properties caused by effects of thermal aging on superaustenitic stainless steel was investigated using electrochemical anodic polarization test in a KOH electrolyte. Carbides and ${\eta}-phase(Fe_2Mo)$ precipitated in the grain boundaries seem to deteriorate the mechanical properties by decreasing cohesive strength in the grain boundaries and to promote the current density observed in electrochemical polarization curves, The electrochemical and mechanical properties of superaustenitic stainless steel decreased significantly in the specimen aged at $650^{\circ}C$ corresponding to the sensitization temperature for conventional austenitic stainless steels.

Cr-Mo강 시효재의 취화손상 평가를 위한 전기화학적 분극시험에 관한 연구 (A Study on Electrochemical Polarization Test for Embrittlement Damage Evaluation of Aged Cr-Mo Steel)

  • 유효선
    • 비파괴검사학회지
    • /
    • 제19권6호
    • /
    • pp.411-419
    • /
    • 1999
  • 에너지 변환설비와 관련된 기계구조물의 내열재료는 $350^{\circ}C{\sim}550^{\circ}C$의 온도범위에서 장시간 사용되는데 이때 조직의 결정입계에는 불순물 원소(P, Sn, Sb등)의 편석과 탄화물의 석출 등으로 인하여 재료의 취화 현상이 발생되고, 그로 인해 입계강도의 저하가 초래된다. 따라서 노후화된 고온설비의 안전성 및 효율적인 운전조건을 확보하고, 취성파괴 방지를 위해서는 취화손상의 정량적 평가는 매우 중요하다. 그러나 가동중인 고온설비에서 파괴시험을 위한 대량의 시험편채취가 거의 불가능한 경우가 대부분이므로 비파괴적인 시험방법이 요구된다. 본 연구에서는 인공시효열처리된 2.25Cr-1Mo강의 비파괴적인 취화손상도 평가를 위해 적정 부식환경하에서 전기화학적 분극시험 방법에 의한 최적의 평가인자를 조사하였다. 또한 전기화학 시험결과들은 준비파괴시험인 SP시험에 의한 취화도 평가결과와 비교되었다.

  • PDF

고분자 전해질 연료전지 양극 작동 환경에서 실험 시간 및 작동 전압 변수에 따른 316L 스테인리스강의 전기화학적 특성과 손상 거동 (Electrochemical Characteristics and Damage Behavior in Cathode Operating Conditions of 316L Stainless Steel with Test Time and Applied Potential in Metallic Bipolar Plates for PEMFC)

  • 신동호;김성종
    • Corrosion Science and Technology
    • /
    • 제20권6호
    • /
    • pp.451-465
    • /
    • 2021
  • In this investigation, electrochemical characteristics and damage behavior of 316L stainless steel polymer electrolyte membrane fuel cell(PEMFC) were analyzed by potentiodynamic and potentiostatic tests in cathode operating condition of PEMFC. As the result of potentiodynamic polarization test, range of passive region was larger than range of active region. In the result of potentiostatic test, damage depth and width, pit volume, and surface roughness were increased 1.57, 1.27, 2.48, and 1.34 times, respectively, at 1.2 V compared to 0.6 V at 24 hours. Also, as a result of linear regression analysis of damage depth and width graph, trend lines of damage depth and width according to applied potentials were 16.6 and 14.3 times larger, respectively. This demonstrated that applied potential had a greater effect on pitting damage depth of 316L stainless steel. The damage tendency values were 0.329 at 6 hours and 0.633 at 24 hours with applied potentials, representing rapid growth in depth direction according to the test times and applied potentials. Scanning electron microscopy images revealed that surface of specimen exhibited clear pitting damage with test times and applied potentials, which was thought to be because a stable oxide film was formed by Cr and Mo.

오스테나이트계 스테인리스강과 니켈합금의 해수 농도 변화에 따른 전기화학적 부식 손상 특성 (Electrochemical Corrosion Damage Characteristics of Austenite Stainless Steel and Nickel Alloy with Various Seawater Concentrations)

  • 허호성;김성종
    • Corrosion Science and Technology
    • /
    • 제20권5호
    • /
    • pp.281-288
    • /
    • 2021
  • Due to advancement of the industry, operation of a device in a harsh environment is increasing. Especially, the marine environment contains Cl- ions which causes localized corrosion such as pitting and crevice corrosion of stainless steel and various metals. In this study, electrochemical corrosion behaviors of austenitic stainless steel (STS 316L) and nickel alloy (Inconel 600) with different seawater concentrations (fresh water, seawater, mixed water) were investigated. The STS 316L and Inconel 600 were etched in 10% oxalic acid and composed of an austenitic phase. Results of Tafel analysis in seawater showed that STS 316L and Inconel 600 presented the highest corrosion current densities of 7.75 × 10-4 mA/cm2 and 1.11 × 10-4 mA/cm2 and the most negative pitting potentials of 0.94 V and 1.06 V, respectively. The maximum damage depths and surface damage ratio by pitting corrosion increased with chloride concentration. The STS 316L had higher PREN than Inconel 600. However, the surface damage and weight loss of Inconel 600 were superior to STS 316L. It was difficult to compare the pitting resistance of STS 316L based on Fe and Inconel 600 based on Ni with PREN simply.

Al 6061-T6 합금의 해수 내 캐비테이션 진폭에 따른 캐비테이션-침식 조건하에서 전기화학적 특성 (Electrochemical Characteristics with Cavitation Amplitude Under Cavitation Erosion of 6061-T6 in Seawater)

  • 황현규;김성종
    • Corrosion Science and Technology
    • /
    • 제19권6호
    • /
    • pp.318-325
    • /
    • 2020
  • Generally, Al alloys of 5000 and 6000 series show excellent weldability, workability, and specific strength, and are widely used in ship building. A combined experiment via cavitation erosion and corrosion damage involving 6061-T6 Al alloy was performed using potentiodynamic polarization under cavitation erosion (hybrid experiments) with amplitude (cavitation strength). The corrosion current density was approximately 52-fold higher at 30 μm than under static conditions, suggesting that the amplitude greatly affected the damage. The degree of damage increased with increasing cavitation amplitude. After the hybrid experiment, the corrosion rate was compared according to the weight loss and damage depth, and the relationship between the two values was expressed as alpha value. The alpha (α) values at amplitudes of 5 μm, 10 μm and 30 μm were 5.11, 12.81 and 8.74, respectively, suggesting that the α value at 10 μm was greater than at 5 μm, and indicating local corrosion damage. However, the α value at 30 μm was smaller than that of 10 μm, which is attributed to higher damage via uniform corrosion than damage induced by local corrosion.