鎳基超合金Inconel 625及René125在600~800℃之H2/H2S/Ar混和氣氛下的硫化研究

The Sulfidation of Nickel-base Superalloys Inconel 625 and René 125 in the H2/H2S/Ar Gas Mixture

本研究探討兩種鎳基超合金，Inconel 625（In-625）及René125（Rn-125）在600 ~ 800oC之H2/H2S/Ar混合氣氛下的高溫硫化行為。結果顯示，In-625及Rn-125之硫化動力學皆遵守拋物線型定律，且硫化反應速率隨著溫度上升而加快。
In-625合金硫化後生成內、外層兩層硫化物，其中，外層外部主要生成硫化鎳（Ni3S2/Ni7S6），但外層內部包含硫化鉻（Cr2S3/Cr3S4）及硫化鎳（Ni3S2/Ni7S6），而內層為硫化鉻（Cr2S3/Cr3S4）、硫化鉬（Mo3S4）與硫化鐵鉬（FeMo2S4）。Rn-125合金硫化後，亦生成內、外層硫化物，包括外層外部為硫化鎳（Ni3S2）及硫化鈷（Co9S8），則外層內部更有硫化鎳鉻（NiCr2S4）生成，內層主要為硫化鎳鉻（NiCr2S4）、硫化鋁（Al2S3）、微量硫化鉻（Cr2S3/Cr3S4）及硫化鎳（Ni3S2）；由白金指標實驗得知，所有白金皆位於內、外硫化層之間，這表示外層硫化物生成主要是由陽離子向外擴散所致，而內層硫化物的形成主要是由陰離子向內擴散所致。

The sulfidation of two nickel-base superalloys, Inconel 625(In-625) and René 125(Rn-125), was studied over the temperature range 600 ~ 800oC in the H2/H2S/Ar gas mixture. The results showed that the sulfidation kinetics of the two alloys follows the parabolic rate law, and the corrosion rate constants increased with increasing temperature.
The scales formed on In-625 were duplex and heterophasic, consisting of an outermost outer layer of Ni3S2, an innermost outer layer of Ni3S2 and Cr2S3/Cr3S4, and an inner layer of Cr2S3/Cr3S4 and NiCr2S4. In addition, the scales formed on Rn-125 were also duplex, consisting of a heterophasic outer layer of Ni3S2 and Co3S4, and an inner layer of CoNi2S4, Co2S4/Co9S8, Cr2S3, CoCr2S4, and minor amounts of Al2S3. Platinum markers are always located at the interface between the inner and outer layers, suggesting that the outer layer grew by outward transport of cations and the inner layer grew by the inward diffusion of sulfur.