本研究採用不同鉻含量之鉻鉬鋼(0、2.25、5、9、12 wt.% Cr)，於550 °C空氣/氮氣氣氛下之LiNO3-NaNO3-KNO3共晶融鹽進行250、500與1000小時之浸滯腐蝕實驗。目的為探討不同氣氛下，鉻鉬鋼在融鹽中之腐蝕是否會產生差異，及鋼料鉻含量對其於融鹽中的高溫腐蝕行為影響。研究結果顯示，各鋼料的重量增重皆與腐蝕時間成正比，在空氣氣氛下之重量增重大於氮氣氣氛；並且隨著鋼料鉻含量的增加，其重量增重逐步降低，鉻含量達到9 wt.%時，重量增重會大幅降低。鋼料腐蝕後的顯微結構分析顯示，不同氣氛下，鋼料會生成不同的腐蝕產物。在空氣下，各鋼料的腐蝕皮膜是由外側LiFe5O8與內側(Fe,Cr)3O4組成；氮氣氣氛下，則是由外側LiFeO2與內側(Fe,Cr)3O4組成，且鋼料在氮氣氣氛下被融鹽腐蝕的程度較輕微。而腐蝕後之皮膜厚度隨鋼料的鉻含量增加而減薄，並且在鉻含量達到9 wt.%時，抵抗融鹽腐蝕的能力可以得到大幅改善。

This study investigated the effect of the chromium on the high-temperature corrosion behavior of Cr-Mo steel in molten salt under air/nitrogen atmosphere. The corrosion test was performed by immersing Cr-Mo steels with different chromium content (0, 2.25, 5, 9, 12 wt.% Cr) in static molten LiNO3-NaNO3-KNO3 eutectic salt at 550 °C for 250, 500 and 1000 hours with air and nitrogen cover gas. The result shows the weight gains of the steels are directly proportional to the corrosion time but are inversely proportional to the chromium content. And the weight gains under air atmosphere is greater than under nitrogen atmosphere. The microstructure analysis of the corroded steels shows the corrosion scales on the steels are composed of an outer LiFe5O8、LiFeO2 and an inner (Fe,Cr)3O4 layers under air atmosphere ; an outer LiFeO2 and an inner (Fe,Cr)3O4 layers when the molten salt cover with nitrogen gas. Also, the thickness of the corrosion scales decreased with the chromium content increased. According to the result of this study, it has been confirmed that the corrosion resistance of steel in the molten slat can be dramatically improved when the chromium content reached 9 wt.%.

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