沃斯田體系不銹鋼於氯化鈉誘發之腐蝕形態研究

The Study of NaCl-induced Corrosion Morphologies of Austenitic Stainless Steels

三種沃斯田體系Fe-Cr-Ni合金（253MA、310SS和353MA）披覆2mg/cm2 NaCl，於850℃之流動空氣中進行高溫腐蝕實驗。實驗結果顯示，初期披覆NaCl會加速合金之氧化，其加速氧化的方式是以氯氧化反應為起始反應，接著以氯化／氧化循環反應的方式持續加速氧化反應的進行，結果導致三式合金形成一厚的皮膜，並且於基材表面產生許多相連通之孔洞網，這些隧道狀的孔洞填充許多腐蝕產物，並且部分腐蝕產物形成於孔洞表面。於本研究，310表現最佳之抗蝕性，353MA次之，253MA較差。

Three austenitic Fe-Cr-Ni alloys (253MA, 310SS and 353MA) coated with 2mg/cm2 NaCl have been oxidized at 850℃ in a slow airflow. The results indicated that the initial NaCl coating accelerated oxidation of alloys by oxychlorination and chlorination/ oxygen-substitution cyclic reactions, resulting in the formation of thick scale and an interconnecting viod network in the substrate. Voids were tunnels in shape. Some were filled with corrosion products and some corrosion products were formed on the walls of the voids. The thickness of metal loss was related to the consumption of both chromium and iron in the alloy substrate. In this study, 310 revealed better corrosion resistance after 36 hr exposure, followed by 353MA, and the worst was 253MA.