Si对Hastelloy N合金氧化行为的影响

Effects of Silicon on the Oxidation Behavior of Hastelloy N Superalloy at 850 °C

利用不连续增重法,研究了不同Si含量的Hastelloy N合金850℃恒温氧化行为。结果表明,随Si含量的增加,氧化动力学曲线保持抛物线规律。氧化100 h后,氧化膜出现分层现象,最外层均为NiO、NiFe_2O_4等复合氧化物,中间层为Cr_2O_3、MoO_2等氧化物。由于在氧化层与基体界面处形成连续致密的SiO_2层,有效阻止Cr离子向外扩散进入氧化层,促进Hastelloy N合金中间层形成较为致密的Cr_2O_3氧化层,提高了合金的抗氧化性能。

The isothermal oxidation behavior of Hastelloy N superalloy with different silicon contents at 850°C in air was investigated by a discontinuous increasing weight method.The results show that oxidation mass gain kinetics of the samples follows the parabolic law with increasing Si contest.It is observed that the surfaces of the alloys exhibit a multi-layer structure after 100 h oxidation.The outer oxide film of Hastelloy N superalloy mainly consists of NiO,NiFe2O4 and other oxide composites.The middle layer is confirmed to be Cr2O3 and MoO2.A continuous and dense SiO2 sublayer is formed at the metal-oxide interface,it is effective to prevent Cr diffusion.The addition of Si promotes the formation of a relatively continuous and compact Cr2O3 and it can strongly improve the oxidation resistance.