低合金鋼在含硫氣氛中之高溫腐蝕行為研究

High Temperature Corrosion Behavior of Low Alloy Steel in Sulfur-containing Atmosphere

本研究探討TSTM A213-T11低合金鋼管材在980℃含硫之氣氛中的腐蝕行為，藉由分析腐蝕產物的化學組成及微觀組織以瞭解腐蝕機制。試片於980℃之管型爐中，不同濃度硫／氧混和氣氛下持溫不同時間後取出進行分析。系統之含硫氣氛以加熱含硫鋼罐產生硫蒸氣並以氮氣為載體將硫蒸氣通入高溫管型爐中。結果顯示，試片於高溫空氣和不同硫分壓氣氛中試驗，其腐蝕動力學皆遵循拋物線定律，且隨環境中硫分壓的提高，試片單位時間增重也隨之上升。SEM/EDS分析結果顯示，試片在含硫環境氧化20分鐘後，銹層內層出現硫、氧化物混合層。銹層從表面經過微量逐步研磨後，其XRD分析結果也顯示銹層內層呈現層狀交錯之分佈的狀態，而FeS存在於銹層內部。

High temperature corrosion behavior of ASTM A213-T11 low alloy steel in sulfur-containing atmosphere with different partial pressure at 980 ℃ was studied. Corrosion test was conducted in a tube furnace purged with sulfur vapor-containing gas. The sulfur vapor was generated through heating up a steel container and simultaneously purged with nitrogen gas into the tube furnace. By altering the temperature of sulfur-containing can, sulfur partial pressure of system could be controlled. Both in air and in low sulfur partial pressure mixed gases, the corrosion rate is governed by parabolic law and increased with increasing sulfur partial pressure. Cross section SEM/EDS examination showed that the scale exhibited layered-structure while the inner layer was in porous form. XRD analyses with successive surface corrosion product grinding revealed that FeS was formed in the inner scale in laminar structure.