In order to enhance corrosion resistance of stainless steel (SS) 316LN at high temperature environments, surface modification was carried out by Si deposition and subsequent heat treatment at 900 °C for 1 h. This resulted in the formation of Fe₅Ni₃Si₂ phase on the surface region. The surface-modified alloy was exposed to high temperature S-CO₂ (650 °C, 20 MPa) and steam (650 °C, 0.1 MPa) for 500 h and evaluated for its corrosion behavior in comparison to the as-received alloy. In S-CO₂ environment, the as-received SS 316LN showed severe oxide spallation and thick Fe-rich oxide formation, while the surface-modified alloy formed a continuous and adherent Si- and Cr-rich oxide layer. In steam, as-received SS 316LN formed very thick duplex Fe- and Cr-rich oxide layers. On the other hand, surface-modified SS 316LN formed notably thinner oxides, which could be attributed to the formation of Si-rich oxide under outer Fe-rich oxides on the surface-modified alloy. Thus, in view of the weight changes, oxide thickness, and morphologies of the two conditions, it was found that Si diffusion coating was effective in improving the corrosion resistance of SS 316LN in both S-CO₂ and steam environments.

中文翻译：

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高温超临界二氧化碳和蒸汽环境下奥氏体铁基合金上硅扩散涂层的腐蚀行为

为了增强316LN不锈钢（SS）在高温环境下的耐腐蚀性，通过硅沉积和随后在900°C的热处理1 h进行了表面改性。这导致在表面区域上形成Fe ₅ Ni ₃ Si ₂相。将表面改性的合金暴露于高温S-CO ₂（650°C，20 MPa）和蒸汽（650°C，0.1 MPa）中500小时，并与原合金进行比较，评估其腐蚀行为。在S-CO _2中在这种环境下，SS 316LN表现出严重的氧化物剥落和浓厚的富铁氧化物形成，而表面改性合金形成了连续且粘附的富硅和富铬氧化物层。在蒸汽中，收到的SS 316LN形成了非常厚的双相富铁和富铬氧化物层。另一方面，经表面改性的SS 316LN形成的氧化物明显更薄，这可以归因于在表面改性合金上在外富铁氧化物下形成了富硅氧化物。因此，考虑到两个条件的重量变化，氧化物厚度和形态，发现在S-CO ₂和蒸汽环境中，Si扩散涂层均有效地改善了SS 316LN的耐腐蚀性。