본 연구는 절탄기 튜브의 저온부식 손상을 방지하기 위해 Inconel 625 용사재료를 활용하여 아크 열용사 코팅기술 적용 후 실링 처리를 실시하였다. 용사코팅(TSC) 층의 내식성 분석을 위해 0.5 wt% 황산 수용액에서 다양한 전기화학적 실험을 진행하였다. 양극분극 실험 후에는 주사전자현미경과 EDS 성분분석을 통해 부식 손상 정도를 파악하였다. 자연전위 계측 시 TSC+실링처리(TSC+Sealing)의 안정적인 전위 형성을 통해 실링처리 효과를 확인하였다. 양극분극 실험 결과 TSC와 TSC+Sealing에서 부동태 영역이 확인되었으며, 부식 손상 역시 관찰되지 않아 내식성이 개선되었다. 더불어 타펠분석에 의해 산출된 부식전위와 부식전류밀도 분석 결과 TSC+Sealing의 내식성이 가장 우수하게 나타났다.

Hot-press forming(HPF) steel can be applied successfully to auto parts because of its superior mechanical properties. However, its resistances to aqueous corrosion and the subsequent hydrogen embrittlement(HE) decrease significantly when the steel is exposed to corrosive environments. Considering that the resistances are greatly dependent on the properties of coating materials formed on the steel surface, the characteristics of the corrosion and hydrogen diffusion behaviors regarding the types of coating material should be clearly understood. Electrochemical polarization and impedance measurements reveal a higher corrosion potential and polarization resistance and a lower corrosion current of the Al-coating compared with Zn-coating. Furthermore, it was expected that the diffusion kinetics of the hydrogen atoms would be much slower in the Al-coating, and this would be due mainly to the much lower diffusion coefficient of hydrogen in the Al-coating with a face-centered cubic structure. The superior surface inhibiting effect of the Al-coating, however, is degraded by the formation of local cracks in the coated layer under severe stress conditions, and therefore further study will be necessary to gain a clearer understanding of the effect of cracks formed on the coated layer on the subsequent corrosion and hydrogen diffusion behaviors.

The electrochemical performance for the corrosion of zinc anodes according to particle size and shape as anode in Zn/air batteries was study. We prepared five samples of Zn powder with different particle size and morphol- ogy. For analysis the particle size of theme, we measured particle size analysis (PSA). As the result, sample (e) had smaller particle size with 10.334 µm than others. For measuring the electrochemical performance of them, we measured the cyclic voltammetry and linear polarization in three electrode system (half-cell). For measuring the morphology change of them before and after cyclic voltammetry, we measured Field Emission Scanning Electron Microscope (FE- SEM). From the cyclic voltammetry, as the zinc powder had small size, we knew that it had large diffusion coefficient. From the linear polarization, as the zinc powder had small size, it was a good state with high polarization resistance as anode in Zn/air batteries. From the SEM images, the particle size had increased due to the dendrite formation after cyclic voltammetry. Therefore, the sample (e) with small size would have the best electrochemical performance between these samples.

본 논문은 지하매설 철 구조물의 전기적 부식방지를 위해 Mg 희생양극을 사용하는 부식방지 기술에 대한 연구 또한 활발히 진행되고 있다. Mg 희생양극은 지하에 매설되는 철 구조물(파이프, 탱크, 파일, 고정 앵커 등)을 부식으로부터 보호하기 위하여 사용되는 것이다. 본 연구에서는 종래의 산화 소화용 표면 보호재로 이용되고 있는 비교적 값이 싼 CaCl2 염화물을 이용하여 마그네슘 합금제조 시 CaCl2 염화물의 표면보호 효과 및 제조된 Mg-Ca 합금들의 전기화학적 특성을 조사하였다 금속 Ca가 아닌 산화방지 및 소화 용제로 이용되고 있는 염화물(CaCl2)을 이용하여 자연부식 전위 값이 -1.695VSCE 이하, 사용효율도 59% 이상인 Mg-Mn-Ca 희생양극제의 제조기술을 확립하였다.

The corrosion performance of a powder metallurgical aluminum alloy in aeronautical environments was studied for both as sintered and heat treated states. Sintered samples were obtained by uniaxial pressing of an Al-Cu-Mg prealloyed powder followed by liquid phase sintering. The heat treatments applied were T4 and T6. Corrosion behaviour was assessed by means of potentiodynamic polarization. Results for the equivalent commercial wrought counterpart, AA2024-T3, are also presented for comparison. Similar corrosion performance was observed for both as sintered and AA2024-T3 samples, while corrosion resistance of the PM materials was improved by the heat treatment, especially in the T4 state.

NaCl과 LiNO2의 첨가량에 따른 콘크리트에 매립된 철근의 부식거동을 전기화학적 임피던스 분광법을 이용하여 고찰하였다. 부식 가속 방법중 하나인 건습반복법을 이용하여 단기간 내에 부식현상을 촉진하였으며, 측정된 임피던스 값을 통해 등가회로를 제안할 수 있었다. NaCl 1.2 kg/m3이 첨가된 콘크리트에 매립된 철근의 부동태 피막이 빠르게 파괴되는 것을 확인할 수 있었으며, 염화물 첨가량 대비 0.6M의 LiNO2를 첨가한 경우 부식진행속도가 크게 저하하는 것을 확인할 수 있었다. 또한 염화물 첨가량 대비 1.2M의 LiNO2를 첨가한 경우 부동태 피 막이 부식가속시간이 지나도 파괴되지 않고 성능이 유지되는 것을 확인할 수 있었다.

This study is based on the electrochemical theory which aims to get the quantitative evaluation about corrosion protection of Zn-Sn metal spray method. The various existing corrosion resistance method and various mixture ratio of Zn-Sn metal spray method is applied with structural steel which is measured change of polarization resistance and corrosion potential. So corrosion protection of Zn-Sn metal spray method is tested. Consequently, coating side of Zn-Sn metal spray method was lower than electric potential of a structural steel adhesion side. So, Galvanic Protection of Zn-Sn metal spray found that structural steel advanced system. Accordingly, Zn-Sn metal spray method is expected as corrosion protection technology excellent in corrosion prevention of structural steel.

In this study, corrosion potential (Ecorr), corrosion rate, and polarization resistance were measured aimed at inorganic inhibitors (passive film type) and organic inhibitors (absorption type). The experiment was conducted using potentiostat for the variable molar ratio and chloride ion concentration of the components of inhibitors in an aqueous solution of saturated calcium hydroxide targeting corrosion. As a result, it was possible to ensure an anticorrosive performance of at least a 1.2 molar ratio of inorganic inhibitors. Also, the organic inhibitors ensured the prevention of the anticorrosive performance of at least about a 0.3 molar ratio. It also showed the tendency that between polarization resistance and corrosion rate, Ecorr and corrosion rate is inversely proportional to the linear. Conversely, the tendency between polarization resistance and Ecorr is proportional to the linear. Also, a distinct difference in organic and inorganic inhibitors’ relationship to Ecorr, corrosion rate, and polarization resistance was not shown.

In this study, in order to comprehend performance of corrosion inhibitor, the experiment study was conducted about corrosion characteristic of 3 steps(0.0, norm 1/2, norm) compared to organic corrosion inhibitor standard use of liquid and molar 3 steps(0.0, 0.3, 0.6%) of Chloride by added amount of inorganic corrosion inhibitor by the corrosion inhibitor types about 2.4kg/m3, 4.8kg/m3 based on Chloride ion content 1.2kg/m3 for service life prediction of concrete structure by using Poteniostat.

시멘트 대체 재료로서 플라이애쉬의 사용은 시멘트 생산비용을 절감시키는 효과를 창출하였다. 반면에 플라이애쉬 혼입콘크리트는 OPC에 비해 상대적으로 긴 양생시간과 초기강도의 발현 저하를 들 수 있어 이의 해결을 위해 물리적 방법, 온도 및 화학적 방법 등과 같은 다양한 활성화 기술의 적용을 통하여 플라이애쉬 혼입 콘크리트의 수화를 가속시킬 수 있고, 콘크리트의 부식 저항성을 향상시킬 수가 있다. 본 연구에서는 10～40%의 치환률을 가진 활성화된 플라이애쉬 시편을 통해 개방 회로형 전위측정(Open circuit potential measurement)을 수행하였고, 투수시험, 급속염화물침투시험 및 SEM(Scanning electron microscopy)촬영을 통해 OPC 콘크리트와 비교․분석 하였다. 또한, 치환률의 임계범위 20～30%의 경우에 있어서 활성화된 플라이애쉬를 사용한 콘크리트가 열화저항성에 있어서 개선효과가 나타나고 있음을 확인하였다. 또한 플라이애쉬를 화학적으로 활성화시킨 경우가 본 연구에서 수행된 다른 활성화 방법들에 비해 더욱 좋은 결과를 나타나고 있음도 확인하였다.