腐蝕抑制劑對Fe-Co-Ni-Cu-Cr高熵合金於3.5wt% NaCl水溶液中之影響

Effects of Corrosion Inhibitors on the Fe-Co-Ni-Cu-Cr High Entropy Alloy in 3.5wt% NaCl Solution

本研究主要在探討不同腐蝕抑制劑（NaNO2、Na2MoO4、Na3PO4）對Fe-Co-Ni-Cu-Cr高熵合金（簡稱HEA）在3.5wt% NaCl水溶液中的電化學行為和腐蝕抑制效果。結果顯示，所有腐蝕抑制劑，都使試片之腐蝕電位（Ec o r r）升高，腐蝕電流密度降低且鈍化電位區間增大，其中以Na3PO4腐蝕抑制效果最佳，鈍化電流值（Ip a s s i v e）最小，鈍化電位區間也最大，代表產生鈍態保護膜的能力最好。比較在3.5wt% NaCl水溶液中的循環極化曲線，發現高熵合金的腐蝕電位值（Ec o r r）比AISI 304不銹鋼低，腐蝕流密度值（ic o r r）較大，顯示高熵合金較為活潑，因此高熵合金抗蝕性較AISI 304不銹鋼差。由極化曲線顯示此高熵合金在3.5wt% NaCl水溶液中不能自然有效產生鈍態膜，因而出現嚴重的腐蝕行為。

The effects of three corrosion inhibitors (containing NaNO2, Na2MoO4, and Na3PO4) on the corrosion behavior of the Fe-Co-Ni-Cu-Cr high-entropy alloy (HEA) in 3.5% NaCl solution were studied. The results generally showed that the passive potential and corrosion potential increased but the corrosion current density decreased by adding various inhibitors. The addition of Na3PO4 exhibited the best inhibiting-ability among all the inhibitors studied. It showed the lowest passive current (Ip a s s i v e ) and largest passive region (Ep i t-Ec o r r. ). Based on the cyclic polarization curves, the HEA showed a lower Ec o r r , but a higher current density (ic o r r. ), as compared to the results of AISI 304 stainless steel, thus resulting in a poor corrosion-resistance. It was also found that the HEA is unable to form such a complete protective flim to prevent from pitting corrosion.