310耐熱鋼之氯化鈉循環熱腐蝕

Thermal Cycling Hot Corrosion Behavior of 310 Stainless Steel Caused by NaCl Deposit

利用噴覆沉積之方式，探討310耐熱鋼於750℃、800℃及850℃氯化鈉沉積後之循環熱腐蝕行為，比較並瞭解腐蝕氣氛源氯化鈉之補充以及加熱冷卻循環對腐蝕形態之影響。實驗結果顯示，310耐熱鋼於氯化鈉之循環熱腐蝕，由於不斷的補充氯化鈉，使得氯氧化、氯化及再氧化等過程重覆進行，且所形成之外層皮膜於冷卻時剝落，造成其侵蝕總深度隨著循環次數增加呈線性增加。本研究並經由熱力學的分析、形態觀察以及X光之相鑑定，提出310耐熱鋼於氯化鈉沉積熱腐蝕之反應機制。

The NaCl-induced hot corrosion of 310 stainless steel was thermal-cycling investigated at 750-850℃in this study. Effects of the supplying NaCl and the cyclic treatment on the formation of the scale morphology were also explored. The results show that the total depth of attack of the steel increased linearly with increasing cyclic times. The outer scale formed on the steel always spalled after cooling, due presumably to repeating processes of supplying NaCl, oxychloridation, chloridation and reoxidation, which leaded to the trend of the total depth of attack increasing with increasing cyclic times. Through the thermodynamic analysis, morphological studies and phases identification, the reaction mechanisms of alloys were discussed in this study.