论文部分内容阅读
Cyclic oxidation behavior of two-phaseγ+γ’-Ni-22Al-5 and -10 Pt alloys in air with and without 30 vol.%H_2O at 1000℃was investigated.The oxidation of 5 and 10 Pt alloys in air was initially rapid and followed by a slow steady-state stage.The oxidation during this steady-state stage was followed the parabolic rate law,and the parabolic rate constants for the two different Pt content alloys were similar.However the mass change of 5 Pt alloy during the initial rapid oxidation stage was much higher than that of 10 Pt,and it resulted in higher oxidation mass gain on 5 Pt alloy after 500 cycles.Similar oxidation behavior,initial rapid followed by slow steady-state,was observed when the alloys were oxidized in air+30%H_2O,however the initial oxidation mass change in the wet atmosphere was much higher for both alloys than in air.Interestingly,the oxidation rate constants for both alloys during the steady-state stage significantly decreased in the atmosphere with water vapor.Particularly,oxidation mass gain on the 5 Pt alloy was not observed after about 100 cycles of oxidation.
Cyclic oxidation behavior of two-phase γ + γ’-Ni-22Al-5 and -10 Pt alloys in air with and without 30 vol.% H_2O at 1000 ℃ was investigated. The oxidation of 5 and 10 Pt alloys in air was initially rapid and followed by a slow steady-state stage. The oxidation during this steady-state stage was followed the parabolic rate law, and the parabolic rate constants for the two different Pt content alloys were similar.However the mass change of 5 Pt alloy during the initial rapid oxidation stage was much higher than that of 10 Pt, and it resulted in higher oxidation mass gain on 5 Pt alloy after 500 cycles. sudden oxidation behavior, initial rapid followed by slow steady-state, was observed when the alloys were oxidized in air + 30% H_2O, however the initial oxidation mass change in the wet atmosphere was much higher for both alloys than in air.Interestingly, the oxidation rate constants for both alloys during the steady-state stage significantly decreased in the atmosphere with water vapor. Particularly, ox idation mass gain on the 5 Pt alloy was not observed after about 100 cycles of oxidation.