添加釔於Fe-18Al-5Nb在900℃ H2/H2S/H2O混合氣氛下之熱循環腐蝕

The Effect of Y Addition on Thermal Cycling Corrosion of Fe-18Al-5Nb in a H2/H2S/H2O Gas Mixture at 900℃

本研究探討Fe-18Al-5Nb及Fe-18Al-5Nb-0.05Y（文中均為at.%）合金於H2/H2S/H2O混合氣氛下，溫度900℃之熱循環腐蝕行為。研究結果顯示，兩合金在各階段皆遵循抛物線型定律，且隨著熱循環腐蝕的進行，合金的抗蝕性隨循環次數之增加而降低，但Fe-18Al-5Nb-0.05Y的抗蝕性較佳。經由XRD分析結果顯示Fe-18Al-5Nb在第一次熱循環後的腐蝕產物為Nb3S4、FexNbS2、FeS、及Al2O3，第三次熱循環後的腐蝕產物主要是大量FexNbS2，另外還有較少量的Nb3S4及FeS。Fe-18Al-5Nb-0.05Y在第一次熟循環後的腐蝕產物為Nb3S4、Al2O3、FexNbS2及FeS，第三次熱循環後的腐蝕產物主要是Nb3S4及FexNbS2，另外還有少量的Al2O3及FeS。在第一次熱循環後，Fe-18Al-5Nb-0.05Y的腐蝕速率常數值比Fe-18Al-5Nb低了0.10個數量級，第二次熱循環後則低0.23個數量級，第三次熱循環後則低0.45個數量級，證明Y的添加能有效改善腐蝕層的附著性質，進而增進合金的抗蝕性。

The thermal-cycling corrosion behavior of Fe-18Al-5Nb and Fe-18Al-5Nb-0.05Y was studied at 900℃ in a H2/H2S/H2O gas mixture. The corrosion kinetics of Fe-18Al-5Nb and Fe-18Al-5Nb-0.05Y followed the parabolic rate law at all stages. The corrosion resistance decreased with increasing thermal-cycling time, and it was found that Fe-18Al-5Nb-0.05Y has better corrosion resistance than Fe-18Al-5Nb. The parabolic rate constant of Fe-18Al-5Nb-0.05Y is slower than that of Fe-18Al-5Nb by 0.10 order of magnitude after the first thermal cycling, 0.23 order of magnitude after the second thermal cycling, and 0.45 order of magnitude after the third thermal cycling. It appeared that Y addition improved adherence of the scales, resulting in improving corrosion resistance.