Oxygen Permeability Measurements in Ni Using H2/H2O, CO/CO2 and Ni/NiO Rhines Pack Atmospheres
Oxygen Permeability Measurements in Ni Using H2/H2O, CO/CO2 and Ni/NiO Rhines Pack Atmospheres
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DOI：
10.1007/s11085-014-9511-6
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发表时间：
2015-04
影响因子：
2.2
通讯作者：
P. Guo;Jianqiang Zhang;D. Young;C. Konrad
中科院分区：
文献类型：
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作者：
P. Guo;Jianqiang Zhang;D. Young;C. Konrad
众所周知，水蒸气和二氧化碳会加速含铬铁和镍合金的分离氧化。一种说法是，氢或碳的存在促进了铬的内部氧化，导致铬的枯竭和断裂氧化。通过直接测量在氢和碳存在下的氧渗透率来验证这一假设，并与在相同氧分压下只在氧中进行比较来验证这一假说。四种合金，Ni-Cr(1，2，3.5和5wt%)在H2/H2O，CO/CO2和Ni/Nio Rhines包中，在1000℃和1100℃下被氧化。混合气体中的氧分压等于Ni/NiO平衡。根据抛物线动力学，所有情况下都发生了内氧化，表明这是一个扩散控制的过程。由瓦格纳扩散模型推导出的氧渗透系数表明，H2/H2O和CO/CO2反应之间的任何变化都在测量误差范围内(≤10%)。然而，在莱茵河包装环境中，氧气渗透率略高，这归因于形成了更多的针状/板状内部沉淀。结果表明，氢和/或碳的存在不会增加镍的透氧性。
Water vapour and carbon dioxide are known to accelerate breakaway oxidation of chromium-containing iron and nickel alloys. One proposal is that the presence of hydrogen or carbon promotes internal oxidation of chromium, leading to chromium depletion and breakaway oxidation. This hypothesis was tested by direct measurement of oxygen permeability in the presence of hydrogen and carbon, compared with that in only oxygen, under the same partial pressure of oxygen. Four alloys, Ni–Cr (1, 2, 3.5 and 5 wt%), were oxidised in H2/H2O, CO/CO2, and Ni/NiO Rhines packs at 1,000 and 1,100 °C. The oxygen partial pressures in the mixed gases were equal to that of the Ni/NiO equilibrium. Internal oxidation occurred in all cases, according to parabolic kinetics, indicating a diffusion controlled process. Oxygen permeabilities deduced from Wagner’s diffusion model showed that any variation between the H2/H2O and CO/CO2reactions is within the range of measurement error (≤10 %). However, oxygen permeability was slightly higher in the Rhines pack environment, a result attributed to the formation of more needle/plate-like internal precipitates. It is concluded that oxygen permeability in nickel is not increased by the presence of hydrogen and/or carbon.