2205雙相不銹鋼之高溫硫化行為研究

High-Temperature Sulfidation Behavior of 2205 Duplex Stainless Steel

本研究在探討2205雙相不銹鋼（簡稱2205DSS）於溫度500～900℃之H2／H2S與H2／H2S／H2O混合氣氛下的高溫硫化行為。結果顯示，2205DSS之腐蝕動力學遵守拋物線型定律，且腐蝕反應速率隨溫度的上升與水汽的加入而變快。2205DSS硫化後之腐蝕生成物大致分為複雜的內、外兩層硫化物，其中，在H2／H2S混合氣氛下之最外層主要含有硫化鐵（Fe1-XS / FeS）與硫化鐵鎳（(Fe,Ni) 9S8）之硫化物，內層主要為Fe1-XS、FeCr2S4、CrMo2S4、Cr2S3及微量Mo2S3之硫化物。在H2／H2S／H2O混合氣氛下，經腐蝕後並無氧化物生成且腐蝕型態與H2／H2S混合氣氛下相似。由白金指標實驗得知，白金皆位於內層與外層腐蝕層之間，這表示外層硫化物之生成主要是由陽（鐵、鎳及鉻等）離子向外擴散所致，而內層硫化物的生成主要是由硫離子向內擴散所致。

High-temperature sulfidation behavior of 2205 duplex stainless steel (2205DSS) over the temperature range 500~900℃ in H2 / H2S and H2 / H2S / H2O gas mixtures was studied. In general, the corrosion kinetics followed the parabolic rate law in both gas mixtures, and the corrosion rate constants increased with increasing temperature and the presence of water vapor. The scales formed in H2 / H2S mixed gases were complex and heterophasic, consisting of the outer layer of mostly iron sulfide (Fe1-XS or FeS) and iron-nickel sulfide ((Fe,Ni) 9S8), while the inner layer was a heterophasic mixture of Fe1-XS、FeCr2S4、CrMo2S4、Cr2S3 , and minor Mo2S3 . The scales formed in the H2 / H2S / H2O gas mixture were similar to those of in the H2 / H2S gas mixture, and no evidence of any oxides was found. Platinum marker were always located at the interface between the inner and outer scales, suggesting that the outer scale grew by outward transport of cations (Fe, Ni, and Cr) and the inner scale grew by the inward diffusion of sulfur.