알루미늄 표면에 형성된 부동태 박막의 손상에 관한 연구

Abstract

알류미늄 표면에 부착되어 있는 부동태 박막이 Cu, Zn, Sn, 및 Hg 이온을 힘유한 30g/l NaCl 수용액에서 부식 손상되는 현상을 전자현미경과 광학현미경 및 Potentiodynamic method 를 이용하여 연구하였다.

전해 연마한 고순도 알루미늄 표면으로부터 벗겨낸 박막은 세포상 조직으로써 세포밀도 5×10cm-2이었고 결합밀도는 10cm-2이었다. 알루미늄을 30g/l NaCl수요액에서 Potentiodynamic polarization 하였을 때 대단히 큰 이력현상을 보였고 pit의 전파전위(Ep)와 방지전위(Epp)는 전위 상승률에 따라 변하였다. 알루미늄의 Pitting potential(Ec)은 -0.74V(SCE)이었고 전위범위 -0.74V--1.3V에서 부동태 현상을 보였다. 30g/l NaCl 수용액에 Cu 이온을 첨가하였을 때 부식전위 (Eo)가 -0.44V로 상승하였고 Zn, Hg, 이온을 첨가하였을 때 부식전위가 각각 -1.07V alc -1.4V로 감소하였다.

30g/L NaCl 수용액에 Hg 또는 Sn 이온을 첨가하였을 때 전위/전류 곡선의 이력현상과 공식손상(pittig damage)이 관찰되지 않았다.

The corrosion damage of passive film attached on aluminium in 30g/l NaCl solution containing cations such as Cu, Zn, Sn, and Hg has been investigated by the potentiodynamic method together with the use of electron and optical microscopes. The film stripped feom the electropolished superpure aluminium was observed to be of cellular appearance, with a high density of cells(5×10cm-2) and flaws(10cm-2).

Potentiodynamic polarization of aluminium in 30g/l NaCl solution showed a severe hysteresis effect on potential/current curve. Pit propagation potential(E) and pit protection potential(Epp) were dependent on the scan of potential. The Pitting potential of aluminium was about -0.74V(SCE) and the passive behaviour of aluminium was observed in the potential range of -0.74V to -1.3V(SCE). The introduction of Cu ion into the 30g/l NaCl solution increased the corrosion potential(E) to -0.44V and the introduction of Zn or Hg ions decreased corrosion potential to -1.07V and -1.4V respectively. The hysteresis effects of potential/current curve and the pitting damage on the surface of aluminium were not observed by the introduction of Hg or Sn ions into the 30g/l NaCl solutions.

The corrosion damage of passive film attached on aluminium in 30g/l NaCl solution containing cations such as Cu, Zn, Sn, and Hg has been investigated by the potentiodynamic method together with the use of electron and optical microscopes. The film stripped feom the electropolished superpure aluminium was observed to be of cellular appearance, with a high density of cells(5×10cm-2) and flaws(10cm-2).

Potentiodynamic polarization of aluminium in 30g/l NaCl solution showed a severe hysteresis effect on potential/current curve. Pit propagation potential(E) and pit protection potential(Epp) were dependent on the scan of potential. The Pitting potential of aluminium was about -0.74V(SCE) and the passive behaviour of aluminium was observed in the potential range of -0.74V to -1.3V(SCE). The introduction of Cu ion into the 30g/l NaCl solution increased the corrosion potential(E) to -0.44V and the introduction of Zn or Hg ions decreased corrosion potential to -1.07V and -1.4V respectively. The hysteresis effects of potential/current curve and the pitting damage on the surface of aluminium were not observed by the introduction of Hg or Sn ions into the 30g/l NaCl solutions.