Fe50Mo在硫蒸气中的高温硫化

HIGH TEMPERATURE SULFIDATION OF Fe50Mo IN S 2 VAPOUR

应用ＴＧＡ、ＸＲＤ、ＳＥＭ／ＷＤＳ技术研究了Ｆｅ５０Ｍｏ合金在１ｋＰａ，７００～９００℃的硫蒸气中的高温硫化行为．发现在７００℃时硫化遵从抛物线规律，８００和９００℃时则变为线性规律．Ｆｅ５０Ｍｏ的硫化速度常数比纯Ｆｅ的低３～４个数量级，比Ｆｅ２０Ｍｏ和Ｆｅ４０Ｍｏ的抗硫化性能有了显著提高．热处理对合金硫化行为无显著影响．最初只出现ＦｅＳ单一硫化产物层，合金中发生μ相晶界处α－Ｆｅ相的选择硫化．长时间硫化后，ＦｅＳ层下出现ＭｏＳ２内层，其晶体片层垂直于样品表面，有助于扩散传质．但ＭｏＳ２层致密、微观缺陷少，因而有较好的保护性．

The sulfidation kinetics and scale structure of Fe50Mo alloy in 1 kPa S 2 vapor at 700～900℃ were investigated with TGA, XRD, and SEM/WDS respectively. Its kinetics followed parabolic law at 700℃, but linear ones both at 800 and 900℃. The sulfidation rate of Fe50Mo was 3～4 orders of magnitude slower than that of pure Fe, also that of Fe20Mo and Fe40Mo. Heat treatment histroy did not show significant influence on sulfidation behavior of the alloy. The structure of the sulfide scale was dependent on reaction time. In short period, only FeS layer occurred. While, preferential attack of α Fe phase relative to μ phase happened in alloy substrate. After a long duration, MoS 2 layer formed beneath the previous FeS layer,and the orientation of the laminar MoS 2 crystal was perpendicular to the surface of specimen, which could assist particle diffusion along the scale. Nevertheless, higher density of the formed MoS 2 crystal together with lower defect concentration in MoS 2 molecular provided the layer with better protective properties.