添加鈮對Fe-18Al合金在H2/H2S/H2O混合氣氛下的抗高溫腐蝕研究

Effect of Nb Addition on the High Temperature Corrosion Behavior of Fe-18Al in a H2/H2S/H2O Gas Mixture

本研究探討Fe-18Al-xNb合金（其中x=0.2,及10% at.%）於H2/H2S/H2O混合氣氛下，溫度範圍700-900 ℃之間的高溫混合氣腐蝕行為，研究結果顯示，除Fe-18Al-10Nb的腐蝕動力學遵守單一拋物線型行為外，Fe-18Al及Fe-18Al-2Nb均呈現二段式拋物線型行為（含一初始階段的潛伏期和一穩定狀態的反應），且潛伏期的時間隨溫度升高而減少，但隨Nb含量之添加而增長。所有合金的腐蝕速率會隨著溫度的上升而加快，但隨著Nb含量之增加而降低。合金在腐蝕後生成複雜的腐蝕物，經X-光繞射分析得知Fe-18Al之腐蝕物主要為Fes，FeAl2S4及少量的Al2O3；Fe-18Al-2Nb主要生成 FeS，FeNb2S4和少量Al2O3；而Fe-18Al-10Nb主要生成Nb3S4，Al2O3和少量Nb2O5，FeNb2S4。其中，生成Al2O3，Nb2O5及Nb3S4是造成Fe-18Al-10Nb合金腐蝕速率降低的主因。

The corosion behavior of Fe-18Al-xNb alloys(where x = 0, 2, 10 at. %)was study over the temperature range of 700-900℃ in a H2/H2S/H2O gas mixture. The corrosion kinetics of Fe-18Al and Fe-18Al-2Nb followed the two-stage parabolic rate raw, consisting of an initial transient period and a steady-state stage, while the corrosion kinetics of Fe-18Al-10Nb exhibited the single-stage parabolic behavior. The duration of the initial period decreased with increasing temperature, but increased with increasing Nb content. The corrosion rates of all alloys increased with increasing temperature, but decreased with increasing Nb content. The corroded scales formed on Fe-18Al consisted of FeS, FeAl2S4, and minor amount of Al2O3, while the scales formed on Fe-18Al-2Nb consisted of FeS, FeNb2S4, and minor amount of Al2O3. The scales formed on Fe-18Al-10Nb consisted of Nb3S4, Al2O3, and minor amount of Nb2O5, FeNb2S4, and the formation of Al2O3, Nb2O5 and Nb3S4 is responsible for the reduction of the corrosion rate of the Fe-18Al-10Nb alloy.