硝酸鈉對碳鋼抗蝕性之影響

The Effect of Sodium Nitrate on the Corrosion Resistance of Carbon Steel

本研究以動電位極化掃描方法探討：(1)硝酸鈉在氯化鈉水溶液中對碳鋼抗蝕性之影響，(2)鉻酸鹽在pH=3之硝酸鈉水溶液中的抑制行為。其結果歸納如下：1. 當pH=3時，腐蝕速率隨硝酸根離子濃度增加而上昇。在pH=5和11時，腐蝕速率隨硝酸根離子濃度增加而下降。在pH=7和9時若硝酸鈉濃度大於0.2M，腐蝕速率異常昇高。2. 鉻酸鹽在pH=3的硝酸鈉溶液中為腐蝕抑制劑。

The study was executed by potentiodynamic polarization method to investigate: (1) the effect of sodium nitrate on the corrosion of carbon steel in sodium chloride aqueous solutions; (2) the inhibition effect of chromate on the corrsion of carbon steel in sodium nitrate aqueous solution at pH=3. The results are summarlzed as follows: 1. At pH=3, the corrosion rate increases with the increasing concentration of NO3-. At pH=5 and 11, the corrosion rate decreases with the increasing concentration of NO3-. At pH=7 and 9, if [NaNO3] ≧0.2M the corrosion rate increases unnaturally. 2. Chromate acts as an inhibitor in sodium nitrate solutions.