3种不同Cr含量Co-20Re-Cr合金在1000和1100℃的高温氧化行为
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摘要
研究了Co-20Re-20Cr, Co-20Re-25Cr, Co-20Re-30Cr 3种三元合金在1000和1100℃下3.04×10~(-5)Pa氧气中氧化24 h的恒温氧化行为。由于表面形成的氧化膜不能阻止合金中Re以ReO_3形式向外挥发,3种合金都出现了明显的氧化失重现象,Co-20Re-20Cr和Co-20Re-25Cr合金在1100℃时失重更为明显。在两种温度条件下,Co-20Re-20Cr和Co-20Re-25Cr合金的氧化动力学曲线符合抛物线规律,而Co-20Re-30Cr合金的则不符合抛物线规律。3种不同Cr含量合金形成的氧化膜分层明显,最外层是较厚的CoO层,次外层是很厚且疏松多孔的CoCr_2O_4层,内层为极薄的不完全连续但具有一定保护作用的Cr_2O_3层。随着Cr含量的增加,形成的Cr_2O_3层变得更为连续和完整,因此合金的抗氧化性能随之提高,即Co-20Re-30Cr合金的抗高温氧化性能最好。
The iso-thermal oxidation behavior of Co-20 Re-20 Cr, Co-20 Re-25 Cr, and Co-20 Re-30 Cr alloys in 3.04×10~(-5) Pa oxygen at 1000 and 1100 ℃ for 24 h was investigated. The three alloys show continuous mass loss due to the evaporation of Re element in the form of ReO_3. The mass loss is more obvious at 1100 ℃ for Co-20 Re-20 Cr and Co-20 Re-25 Cr alloys. The oxidation kinetics at 1000 and 1100 ℃of Co-20 Re-20 Cr and Co-20 Re-25 Cr obeys parabolic law, while that of Co-20 Re-25 Cr is irregular. Correspondingly, the scales formed on the three alloys with different Cr content have a stratified structure. The outermost layer is composed of CoO, while the inner layer, which is very thick and porous, is composed of CoCr_2O_4. However, the very thin innermost layer composed of Cr_2O_3 is not very continuous and complete, accounting for its limited role for protection. With the increase of Cr content, the oxidation resistance of Co-20 Re-x Cr alloys is enhanced to a certain extent due to the formation of a Cr_2O_3 layer with better continuity and integrity. Furthermore, when the Cr content reaches up to 30%, the oxidation resistance of the alloy was improved greatly.
The iso-thermal oxidation behavior of Co-20 Re-20 Cr, Co-20 Re-25 Cr, and Co-20 Re-30 Cr alloys in 3.04×10~(-5) Pa oxygen at 1000 and 1100 ℃ for 24 h was investigated. The three alloys show continuous mass loss due to the evaporation of Re element in the form of ReO_3. The mass loss is more obvious at 1100 ℃ for Co-20 Re-20 Cr and Co-20 Re-25 Cr alloys. The oxidation kinetics at 1000 and 1100 ℃of Co-20 Re-20 Cr and Co-20 Re-25 Cr obeys parabolic law, while that of Co-20 Re-25 Cr is irregular. Correspondingly, the scales formed on the three alloys with different Cr content have a stratified structure. The outermost layer is composed of CoO, while the inner layer, which is very thick and porous, is composed of CoCr_2O_4. However, the very thin innermost layer composed of Cr_2O_3 is not very continuous and complete, accounting for its limited role for protection. With the increase of Cr content, the oxidation resistance of Co-20 Re-x Cr alloys is enhanced to a certain extent due to the formation of a Cr_2O_3 layer with better continuity and integrity. Furthermore, when the Cr content reaches up to 30%, the oxidation resistance of the alloy was improved greatly.
引文
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[3]Xiao B,Xiang J H,Zhang H H.Cyclic and static oxidation behavior of Fe-Cu-Ni-Al alloy at 900℃[J].J.Chin.Soc.Corros.Prot.,2017,37:69(肖斌,向军淮,张洪华.四元Fe-Cu-Ni-Al合金900℃下的恒温及循环氧化行为[J].中国腐蚀与防护学报,2017,37:69)
[4]Ding Q Q,Yu Q,Li J X,et al.Research progresses of rhenium effect in nickel based superalloys[J].Mater.Rev.,2018,32:110(丁青青,余倩,李吉学等.铼在镍基高温合金中作用机理的研究现状[J].材料导报,2018,32:110)
[5]Perepezko J H.The hotter the engine,the better[J].Science,2009,326:1068
[6]Sato J,Omori T,Oikawa K,et al.Cobalt-base high-temperature alloys[J].Science,2006,312:90
[7]R?sler J,Mukherji D,Baranski T.Co-Re-based alloys:A new class of high temperature materials?[J].Adv.Eng.Mater.,2010,9:876
[8]Gorr B,Christ H J,Mukherji D,et al.Thermodynamic calculations in the development of high-temperature Co-Re-based alloys[J].J.Alloy.Compd.,2014,582:50
[9]Gorr B,Wang L,Burk S,et al.High-temperature oxidation behavior of Mo-Si-B-based and Co-Re-Cr-based alloys[J].Intermetallics,2014,48:34
[10]Niu Y,Cao Z Q,Gesmundo F,et al.Grain size effects on the oxidation of two ternary Cu-Ni-20wt.%Cr alloys at 700-800℃in 1 atm O2[J].Corros.Sci.,2003,45:1125
[11]Xiang J H,Niu Y,Gesmundo F.The oxidation of two ternary FeCu-10 at.%Al alloys in 1 atm of pure O2at 800-900℃[J].Corros.Sci.,2005,47:1493
[12]Wang L,Gorr B,Christ H J,et al.Microstructure and oxidation mechanism evolution of Co-17Re-25Cr-2Si in the temperature range 800-1,100℃[J].Oxid.Met.,2015,83:465
[13]Li T F.High Temperature Oxidation and Hot Corrosion of Metals[M].Beijing:Chemical Industry Press,2003(李铁藩.金属高温氧化和热腐蚀[M].北京:化学工业出版社,2003)
[14]Gorr B,Trindade V,Burk S,et al.Oxidation behaviour of model cobalt-rhenium alloys during short-term exposure to laboratory air at elevated temperature[J].Oxid.Met.,2009,71:157
[15]Gorr B,Burk S,Trindade V B,et al.The effect of pre-oxidation treatment on the high-temperature oxidation of Co-Re-Cr model alloys at laboratory air[J].Oxid.Met.,2010,74:239