不銹鋼在熔融碳酸鹽之耐腐蝕研究

Corrosion Resistance of Stainless Steels in Molten Carbonate Salts

本研究在650℃熔融碳酸鹽（62mol%Li2CO3+38%mol%K2CO3）及燃料電池陽極氣氛（68%H2+17%CO2+15%H2O）下，討論各類型不銹鋼之合金元素及結晶構造對其腐蝕行為的影響。實驗結果說明，不銹鋼的重量損失隨著基材鎳和鉻含量的增加而降低，沃斯田鐵系不銹鋼腐蝕層內層形成Cr2O3，成為阻止鐵向外擴散的障壁，腐蝕層外層的鋰鐵氧化物中有固溶鎳，對耐蝕性有提升的效果，所以沃斯田鐵系不銹鋼在熔融碳酸鹽中的耐蝕性優於肥粒鐵系不銹鋼及雙相不銹鋼。

The corrosion resistance of stainless steels in a molten carbonate bath was investigated by the immersion and semi-immersion test at 650℃ for different exposure times. The corroded samples were analyzed by using the x-ray diffractometer to identify the phases present. Characterization of the corroded scale was carried out with scanning electron microscopy and electron probe microanalysis. Weight loss was decreased as the contents of chromium and nickel increased in stainless steels. Corrosion resistance of austenitic stainless steels was superior to those of ferritic stainless steels and duplex stainless steels, because nickel formed a solid solution in lithium iron oxide which suppressed the outward diffusion of iron through inner Cr2O3 layer.