410不銹鋼在硫酸中之除銹行為研究

The Descaling Behavior of 410 SS in Sulfuric Acid

本研究主要探討經過退火處理之410 SS在硫酸溶液中除銹過程的電化學行為，以及硫酸濃度與溫度的改變對整個除銹行為之影響。利用SEM及XRD觀察經過退火處理之410 SS銹皮表面型態及結構；在酸洗除銹過程中，則利用恆電位儀量測410 SS在硫酸中之開路電位（OCP）變化。實驗結果指出，410 SS經退火處理後之銹皮結構主要為(Cr, Fe)2O3氧化物，經鹽浴處理後試片表面僅發現Fe3O4存在。由電化學試驗結果指出，利用開路電位衰退法可預測酸洗終點；當開路電位衰退至不銹鋼的腐蝕電位時，即表示銹皮已被清除。另外，清除銹皮所需之活化時間（τ）與硫酸之濃度及溫度相關，隨著硫酸濃度及溫度的增加，活化時間會減少。

The electrochemical behavior of annealed 410 SS during descaling in sulfuric acid solution was investigated. The effects of sulfuric acid concentration and temperature on the effectiveness of descaling were also studied. The morphology, composition and structure of the annealed scale formed on 410 SS were examined by using SEM and XRD. During pickling, the open circuit potential (OCP) of each specimen was measured by using a potentiostat. The results showed that the scale formed on 410 SS during annealing was mainly composed of (Cr, Fe)2O3. After molten salt treatment, only Fe3O4 was observed on the surface of the annealed 410 SS. The experimental results demonstrated that potential decay measurement was a reliable method to predict the end point of pickling. As the potential of the annealed stainless steel in sulfuric acid was decayed to the corrosion potential of the bare metal, satisfactory pickling was achieved. Furthermore, the activation time (τ) required for complete descaling decreased with increasing concentration and/or temperature of sulfuric acid used.