硫代硫酸根離子對鎳基690合金於1wt%氯化鈉水溶液中之孔蝕性質影響研究

Effect of Thiosulfate Ion on Pitting Corrosion of Alloy 690 in 1wt% NaCl Solution

李永發(Yung-Fa Lee) ； 李汝桐(Ju-Tung Lee) ； 蔡文達(Wen-Ta Tsai)

《防蝕工程》 12卷2期 (1998/06) Pp. 19-25

https://doi.org/10.6376/JCCE.199806.0019

摘要

本研究主要是以電化學量測方法，探討硫代硫酸根離子(0.001M~0.2M)對鎳基690合金於1wt％氯化鈉水溶液中之孔蝕性質的影響。
由實驗結果顯示；鎳基690合金在硫代硫酸鈉水溶液中，並無孔蝕現象發生。但在1wt% NaCl水溶液中，隨著硫代硫酸根離子的添加，則會降低其孔蝕起始電位值(Enp)，但當添加的硫代硫酸鈉濃度超過某一臨界値時，其Enp值有再上升的趨勢；且當硫代硫酸鈉濃度超過0.1M時，就會有抑制孔蝕的效果發生。
此外，經SEM觀察及EDS分析蝕孔得知，硫代硫酸根離子的添加會使得蝕孔平均深度增加，同時在蝕孔內部並發現有硫元素的存在。這顯示硫代硫酸根離子對於孔蝕的成長扮演重要角色。

關鍵字

鎳基690合金 ； 硫代硫酸根離子 ； 孔蝕

並列摘要

Effect of S2O(superscript 2-)3on pitting corrosion of Alloy 690 in 1wt% NaCl solution was investigated using cyclic potentiodynamic polarization technique. The results showed that no pit was observed on Alloy 690 in the plain S2O(superscript 2-)3(0.001～0.1M) solution. The presence of S2O(superscript 2-)3(≤0.01M) in 1wt% NaCl solution leaded to a decrease in the pit nucleation potential(Enp)of Alloy690 as compared with that without S2O(superscript 2-)3 addition. However, there existed a minimum concentration of S2O(superscript 2-)3,beyond which Enp increased with increasing the concentration of S2O(superscript 2-)3 in NaCl solution. Furthermore, pitting corrosion was inhibited as the S2O(superscript 2-)3 concentration reaching 0.1M. SEM micrographs showed that the pit depth increased with increasing S2O(superscript 2-)3concentration in 1wt% NaCl solution. EDS analysis also revealed the presence of sulfur within the pits. These results demonstrated that S2O(superscript 2-)3 played an important role in pitting corrosion growth process of Alloy 690 in 1wt% NaCl solution.

並列關鍵字

Alloy 690 ； thiosulfate ion ； pitting corrosion