René 77超合金在H2/H2S與H2/H2S/H2O氣氛下之腐蝕性質研究

The High-Temperature Corrosion of Ren 77 Superalloy in H2 / H2S and H2 / H2S / H2O Mixed Gases

本文探討Ren 77鎳基超合金在溫度550～850℃，於混合氣氛H2/H2S（不通水）與H2/H2S/H2O（通水）下之腐蝕行為。研究結果顯示，Ren 77的腐蝕動力學遵守拋物線型定律，且其腐蝕反應常數皆隨著溫度的上升而加快，而Ren 77在相同溫度不同氣氛下其腐蝕速率也有所差異。Ren 77超合金在H2/H2S混和氣氛下腐蝕主要生成內、外兩層腐蝕層，且因溫度高低而異。其中，在T † 600℃之H2/H2S混合氣氛下外層主要是塊狀的硫化鎳（Ni9S8/Ni3S2）與硫化鈷（Co9S8/Co6S5）與微量的硫化鈷鉬（CoMo2S4），內層以硫化鎳（Ni3S2）與硫化鈷鉻（CoCr2S4）為主，並含微量的硫鉻（Cr2S3）及硫化鋁（Al2S3）；當T ‡ 700℃時，外層主要生硫化鎳（Ni3S2）與硫化鈷（Co9S8/Co6S5），並含微量的流化鎳鈷（(NiCo2S4）及硫化鈷鉬（CoMo2S4），內層與T † 600℃相似。但在H2/H2S/H2O氣氛下則生成三層硫化物，外層主要為硫化鎳（Ni7S6/Ni3S2）及少量的硫化鈷（T † 600℃以Co6S5為主，T ‡ 700℃則為Co9S8/Co3S4），中間層主要為硫化鎳（Ni3S2）與硫化鈷（Co9S8/Co6S5），並含有少量之硫化鈷鉬（CoMo2S4）、硫化鈷鉻（CoCr2S4）及硫化鉻（CrS4），內層主要為硫化鉻（Cr3S4/Cr2S3）、硫化鈷鉻（CoCr2S4）、硫化鋁（Al2S3）及微量的氧化鋁（Al2O3）。

The corrosion behavior of Ni-base Ren 77 superalloy was studied in H2/H2S and H2/H2S/H2O mixed gases over the temperature range 550-850 . In general, the corrosion kinetics followed the parabolic rate law in both gas mixtures, and the corrosion rate constants increased with increasing temperature. The scales in H2/H2S mixed gases were duplex and temperature-dependent. The outer-layer scale formed at T † 600℃ consisted of mostly nickel sulfide (Ni9S8/Ni3S2), cobalt sulfide (Co9S8/Co6S5), and minor CoMo2S4, while the inner-layer scale consisted of mostly Ni3S2, CoCr2S4, and minor amounts of Cr2S3 and Al2S3. At T ‡ 700 , minor amount of NiCo2S4 was also detected in the outer-layer scale, and the inner-layer scale was composed of the same sulfides at 600 . On the other hand, the scales formed in H2/H2S/H2O mixed gases were triplex and temperature-independent, consisting of the outer-layer of nickel sulfide (Ni7S6/Ni3S2), cobalt sulfide (Co9S8/Co3S4), of the middle-layer of Ni9S8/Ni3S2, Co9S8/Co6S5, and minor amounts of CoMo2S4, CoCr2S4, and Cr3S4, and of the inner-layer of Cr3S4, CoCr2S4, Al2S3, and minor Al2O