한국해양대학교

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천연해수 중 환경친화적인 전착 코팅막의 형성 메카니즘과 특성 분석

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dc.contributor.author 이찬식 -
dc.date.accessioned 2017-02-22T07:06:28Z -
dc.date.available 2017-02-22T07:06:28Z -
dc.date.issued 2005 -
dc.date.submitted 56823-03-29 -
dc.identifier.uri http://kmou.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002175942 ko_KR
dc.identifier.uri http://repository.kmou.ac.kr/handle/2014.oak/10276 -
dc.description.abstract Mg2+ + 2(OH)- → Mg(OH)2 and Ca2+ + HCO3- + OH- → H2O + CaCO3. These are typically the main compounds in calcareous deposits. It obviously has several advantages compared to the conventional coatings, since the environment-friendly calcareous deposit coating is formed by the elements(Mg2+, Ca2+) naturally present in seawater. Recently, electrodeposition technologies that enables steel structure surface to be protected like a coating method have been studied in developed countries. However, there are some difficulties to maintain both a corrosion resistance for a long period of time and a strong adhesion between deposits and base metal. In this study, environmental friendly calcareous deposit films were formed by an electrodeposition technique on steel substrates in natural seawater. The influence of current density, coating time, seawater temperature and use of steel mesh on composition ratio, structure and morphology of the electrodeposited films were investigated by Scanning Electron Microscopy(SEM), Energy Dispersive Spectroscopy(EDS) and X-Ray Diffractor(XRD). Concludingly, the results of these experiments obtained were as follows -
dc.description.abstract 1/2 O2 + H2O + 2e- → 2OH- and 2H2O + 2e- → H2 + 2OH-. These reactions increase the pH at the metal / seawater interface. The high pH causes precipitation of Mg(OH)2 and CaCO3 in accordance with the formular -
dc.description.abstract Three quarters of the earth is sea. Resources for food and energy with minerals exist abundantly in the sea, which explains why human-being is interested strongly in this world of treasure. Cathodic protection is one of the successful ways to prevent corrosion of steel structures in marine environments. The unique feature of cathodic protection in seawater is the formation of calcareous deposits on cathodic metal surface. Deposits are a consequence of pH increase of the electrolyte adjacent to metal surfaces by cathodic current. The composites of calcareous deposits are mainly calcium carbonate(CaCO3) and magnesium hydroxide(Mg(OH)2). The principles of calcareous deposit formation in seawater had been known for a long time. Cathodic reduction reactions associated with cathodic protection in seawater generate OH- at the metal surface in accordance with the formular -
dc.description.abstract 1. The composites of calcareous deposits was mainly calcium carbonate (CaCO3) and magnesium hydroxide(Mg(OH)2). The formation of calcareous deposits was the consequence of pH increase of the electrolyte adjacent to metal surface influenced by cathodic current. 2. The Mg compositions, in general, were getting decreased regardless of current density but Ca composition was increased with the running time of electrodeposition. 3. Cacareous deposited films formed in Mg-free solutions were showed that corrosion potential was most noble potential value compared to other films formed in natural seawater, Ca-free solutions and Ca+Mg solutions. 4. Mg(OH)2 compounds with brucite structure shaped as flat type were formed at the initial stage of electrodeposition, however, CaCO3 compounds with aragonite structure shaped as flower type was formed in large scale. Besides, Mg(OH)2 compounds were much more formed at 5 A/m2 of current density compared to the 3 A/m2 and 4 A/m2. 5. The apparent general tendency was that the weight of calcareous deposits precipitated was modestly higher at 48 °C than at 28 °C, and it was some 30 % regardless of current density. This means that calcareous deposits are formed more readily on metal surfaces in warm water than in cold, and the other environmental conditions are relatively less influential. 6. The Ca/Mg ratio in the calcareous deposits was higher at 48 °C than at 28 °C. This reveals that the interfacial pH at the metal surface becomes lower with temperature due to the higher solubility of Mg(OH)2 in high temperature, whereas that of CaCO3 decreases. 7. The Ca/Mg ratio was a decreasing tendency with current density increased, which is probably related with the supersaturated calcium ion at the pH of ambient surface seawater, and precipitation of Mg(OH)2 at high pH greater than 9.5. 8. The increased nucleation and growth of uncleus for calcareous deposits at high temperature might be caused by the more active reaction of ion with increasing temperature. -
dc.description.tableofcontents List of Figures iv List of Tables x List of Photos xii Abstract xv 제 1 장 서 론 1 1.1 연구배경 및 목적 1 1.2 연구내용 4 제 2 장 이론적 배경 6 2.1 해수의 일반적 특성 6 2.1.1 화학적 조성 6 2.1.2 해수의 온도 및 유속 6 2.1.3 부식특성 8 2.2 해수 중 부식과 방식의 원리 및 종류 10 2.2.1 부식의 정의 및 원리 10 2.2.2 부식의 종류 17 2.2.3 방식의 원리 및 종류 20 2.2.4 해수 중 강구조물의 부식과 방식 22 2.2.5 해수 중 선박의 부식과 방식 27 2.2.6 해수 중 음극방식의 원리 및 특징 34 2.3 해수 중 형성된 전착물의 관련자료 분석 39 2.3.1 전착물의 형태와 용해 39 2.3.2 해수 조건에 따른 전착물의 형성 영향 43 2.4 해수 중 전착 코팅막의 형성 시도 및 방향 49 2.4.1 일반용액 중 석출 코팅막의 형성관련 기본이해 49 2.4.2 해수 중 전착코팅막 형성을 위한 진행 방향 52 제 3 장 인공 및 천연 해수를 이용하여 제작한 전착 코팅막의 형성 메카니즘 해석 53 3.1 서 론 53 3.2 실험방법 54 3.2.1 시험용 재료 및 전착조건 54 3.2.2 실험 및 분석 방법 55 3.3 실험결과 및 고찰 58 3.3.1 각종 용액 중 일정 전위조건에 따라 형성한 화합물과 전류밀도의 관계 58 3.3.2 천연해수 중 전위변화에 따라 형성한 화합물의 조성원소 분석 61 3.3.3 각종 용액 및 전위조건에서 형성한 화합물의 몰포로지 관찰 64 3.3.4 각종 용액 및 전위조건에서 형성한 화합물의 결정구조 분석 71 3.3.5 각종 용액 중 일정 전류밀도에 따라 형성한 화합물의 부식전위변화 77 3.3.6 각종 용액 중 일정 전위조건에 따라 형성한 화합물의 분극거동 80 3.4 결과요약 82 제 4 장 천연해수 중 전류밀도 및 전착시간 변화에 따른 전착 코팅막의 특성 분석 83 4.1 서 론 83 4.2 실험방법 84 4.2.1 시험용 재료 및 전착조건 84 4.2.2 실험 및 분석 방법 86 4.3 실험결과 및 고찰 89 4.3.1 전착 코팅막의 석출량 분석 89 4.3.2 전착 코팅막의 조성 원소 분석 93 4.3.3 전착 코팅막의 몰포로지 관찰 99 4.3.4 전착 코팅막의 결정구조 분석 108 4.4 결과요약 121 제 5 장 천연해수 중 온도, 전류밀도 및 전착시간 변화에 따른 전착 코팅막의 특성 비교 및 그 응용 122 5.1 서 론 122 5.2 실험방법 122 5.2.1 시험용 재료 및 전착조건 122 5.2.2 실험 및 분석 방법 125 5.3 실험결과 및 고찰 127 5.3.1 전착 코팅막의 석출량 분석 127 5.3.2 전착 코팅막의 조성 원소 분석 131 5.3.3 전착 코팅막의 몰포로지 관찰 143 5.3.4 전착 코팅막의 결정구조 분석 158 5.3.5 천연해수 중 응용 제작한 전착 코팅막 173 5.4 결과요약 177 제 6 장 결 론 179 참 고 문 헌 183 -
dc.language kor -
dc.publisher 한국해양대학교 대학원 -
dc.title 천연해수 중 환경친화적인 전착 코팅막의 형성 메카니즘과 특성 분석 -
dc.title.alternative Properties Analysis and Formation Mechanism of Environmental Friendly Electrodeposit Films in Natural Seawater -
dc.type Thesis -
dc.date.awarded 2005-02 -
dc.contributor.alternativeName Chan-Sik -
dc.contributor.alternativeName Lee -
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