DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | Pyun, Su-Il | - |
dc.contributor.advisor | 변수일 | - |
dc.contributor.author | Na, Kyung-Hwan | - |
dc.contributor.author | 나경환 | - |
dc.date.accessioned | 2011-12-15T01:32:53Z | - |
dc.date.available | 2011-12-15T01:32:53Z | - |
dc.date.issued | 2000 | - |
dc.identifier.uri | http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=158602&flag=dissertation | - |
dc.identifier.uri | http://hdl.handle.net/10203/50775 | - |
dc.description | 학위논문(석사) - 한국과학기술원 : 재료공학과, 2000.2, [ vii, 62 p. ] | - |
dc.description.abstract | The effects of sulphate $(SO_{4}^{2-})$ and nitrate $(NO_{3}^{-})$ ion additives on pit growth of pure aluminium (Al) have been investigated in 0.1 M NaCl solution as a function of anion concentration using potentiodynamic polarization experiment, potentiostatic current transient technique and optical microscopy. The increase in $SO_{4}^{2-}$ and $NO_{3}^{-}$ ion concentrations in NaCl solution raised the pitting potential E_{pit} of pure Al in value and at the same time the steady-state current density at potentials much higher than the $E_{pit}$ on the potentiodynamic polarization curves. This means that $SO_{4}^{2-}$ and $NO_{3}^{-}$ ion additives impede the pit initiation on pure Al surface, but enhance the growth of pre-existing pits. In order to experimentally establish the condition for pure pit growth process, we artificially made a pit on pure Al surface. Potentiostatic current transients obtained from the moment just after adding $SO_{4}^{2-}$ and $NO_{3}^{-}$ ions to NaCl solution revealed that the artificial pit grows more rapidly in the presence of $SO_{4}^{2-}$ and $NO_{3}^{-}$ ions than the absence over time. From observation of the cross-sectional views of the artificial pit, it appeared that the pit grows preferentially in the lateral direction and in the downward direction by adding $SO_{4}^{2-}$ and $NO_{3}^{-}$ ions to NaCl solution, respectively. Based upon the experimental results, two different pit growth promotion mechanisms by anion additives can be proposed: promotion by preferential attack of $SO_{4}^{2-}$ ions more mobile than $Cl^{-}$ ions in $SO_{4}^{2-}$ ion-containing solution; promotion by the production of nitrate salt from $NO_{3}^{-}$ ions more oxidizing than chloride salt from $Cl^{-}$ ions in $NO_{3}^{-}$ ion-containing solution. Both cases may enhance the dissolution of bare Al metal, thus accelerating the pit growth of pure Al in NaCl solution.`` | eng |
dc.language | eng | - |
dc.publisher | 한국과학기술원 | - |
dc.subject | Aluminium | - |
dc.subject | Pitting corrosion | - |
dc.subject | Ion additive | - |
dc.subject | Chloride ion | - |
dc.subject | 염화이온 | - |
dc.subject | 알루미늄 | - |
dc.subject | 공식 | - |
dc.subject | 이온 첨가제 | - |
dc.title | (A) study on the effects of sulphate and nitrate ion additives on pit growth of pure aluminium in 0.1 M NaCl solution | - |
dc.title.alternative | 0.1 M NaCl 수용액에서 순수한 알루미늄의 핏트 성장에 미치는 황산/질산 이온 첨가제의 영향에 대한 연구 | - |
dc.type | Thesis(Master) | - |
dc.identifier.CNRN | 158602/325007 | - |
dc.description.department | 한국과학기술원 : 재료공학과, | - |
dc.identifier.uid | 000983178 | - |
dc.contributor.localauthor | Pyun, Su-Il | - |
dc.contributor.localauthor | 변수일 | - |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.