表面状态对NiTi记忆合金在H2-H2O气氛下氧化行为的影响

Influence of Surface Condition on Oxidation Behavior of NiTi Memory Alloy in H2-H2O Atmosphere

研究了不同表面状态（分别通过电解抛光、机械抛光、砂纸打磨和喷砂得到）的Ni Ti记忆合金试样在500℃、H2-H2O气氛下氧化10 h的氧化行为。通过热重天平、X射线衍射、扫描电镜、能谱研究了合金的氧化动力学、氧化膜的相组成、形貌和成分。结果表明：不同表面状态的NiTi记忆合金在H2-H2O气氛下氧化都遵循立方规律。表面状态对氧化膜形貌和成分的影响显著。电解抛光和喷砂试样氧化膜有剥落和开裂;机械抛光试样以及砂纸打磨的试样形成了致密完整的氧化膜。

The oxidation behaviors of Ni Ti memory alloy with different surface conditions（obtained by electrolytic polished, mechanical polished, grinded and sandblasted, respectively） after oxidation at 500 ℃ in H2-H2O atmosphere for 10 h were studied. The oxidation kinetics, scale phase composition, morphology and composition of the alloy were studied by thermal balance, XRD, SEM and EDS. The results show that the oxidation kinetics of Ni Ti alloy with different surface conditions follows the cubic law. The surface condition has significant influence on the morphology and composition of the oxide film. Spallation and cracking appear on the electrolytic polished and sandblasted samples. The mechanical polished sample and grinded sample form dense and complete oxide films.