T91鍋爐用鋼在650～850℃乾空氣下循環氧化之研究

Cyclic-oxidation of the T91 Boiler Steel at 650 ~ 850 ℃ in Dry Air

本研究主要探討9Cr-1Mo鍋爐用鋼（T91）在650 ~ 850℃熱循環條件下的高溫氧化行為。研究結果顯示，T91的氧化速率隨著溫度增加而增加。T91在循環氧化下形成的氧化物因溫度高低而有所不同，在650℃時，表面生成具有保護性的(Fe,Cr)2O3與(Fe,Cr)3O4，而在750℃氧化時，氧化物主要為外層的Fe2O3與Fe3O4以及內層的(Fe,Cr)3O4，當850℃氧化時，氧化層有垂直的裂縫產生，主要為Fe2O3，以致使氧化速率加速。

High temperature cyclic-oxidation of the 9Cr-1Mo steel (T91) was studied over the temperature range of 650 ~ 850 ℃ in dry air. The results showed that the oxidation-rate constants (kp values) increased steadily with temperature. The compositions of the scales formed on the T91 steel were closely related to test temperature. These scales consisted of (Fe,Cr)2O3 and (Fe,Cr)3O4 650 ℃, of an outer layer of Fe2O3 and Fe3O4 and an inner layer of (Fe,Cr)3O4 at 750 ℃, and of exclusive Fe2O3 at 850 ℃.