石墨含量对镍基高温合金在900 oC氧化行为的影响

Effect of Graphite Addition on Oxidation Behavior of Ni-Cr-Based Superalloy at 900 oC

摘要:

采用粉末冶金方法制备不同石墨含量(0 %、3 %、6 %)的镍基高温合金，研究合金材料在900 ℃和100 h下的恒温氧化行为，用扫描电镜和X射线衍射对其氧化表面形貌和成分进行观察和分析。结果表明: 石墨含量较低(0%，3%)时，镍基合金氧化动力学符合抛物线规律，表面氧化膜无剥落；石墨含量为0%的合金氧化膜由Cr2O3 和NiCr2O4 组成，石墨含量为3%的合金氧化膜由Cr2O3组成，当石墨含量增加到6%时，大量石墨的氧化分解导致合金初始氧化严重，石墨分解后的孔洞加速氧化反应过程。根据氧化膜的组成分析了

Abstract:

Nickel-based alloys with different contents of graphite were prepared by powder metallurgy method. High temperature oxidation resistance of these alloys was studied by high temperature test at 900 ℃ for 100 h in static air. Morphology of oxides was studied by SEM and their composition was analyzed by XRD. The result shows that the kinetic curves of oxidation for nickel-based alloys with lower content of graphite obey the parabolic law. The oxide films consist of Cr2O3 and NiCr2O4 when the alloy contains no graphite. The oxide film consists of Cr2O3 when the alloy contains 3% graphite. If graphite content increases to 6%, the oxidative decomposition of graphite leads to severe initial oxidation, and mass gain takes place significantly; the cavity after decomposition of graphite accelerates the process of oxidation reaction. The oxidation mechanism of the alloy has also been suggested by the phase composition analyses of oxide film