可伐合金在模拟现场N_2/H_2O二元气氛下的氧化行为

Oxidation behavior of kovar alloy in N_2/H_2O atmosphere under simulated field condition

采用称重法、X射线衍射(XRD)和扫描电子显微镜(SEM)研究了可伐合金(Fe-29Ni-17Co)在模拟现场N2/H2O二元气氛下的氧化行为.可伐合金在1000℃不同露点的N2中氧化的增重曲线表明其氧化动力学遵循抛物线规律.XRD和SEM分析显示了在上述条件下表面氧化物的组成和形貌.通过热力学计算说明可伐合金在现场的N2/H2O二元气氛下氧化时,外界空气会渗入炉内增加氧分压,导致表面氧化物中不可避免存在α-Fe2O3.在露点温度较高和氧化时间较长时,生成α-Fe2O3的数量会超过Fe3O4.

The oxidation behavior of kovar alloy （Fe-29Ni-17Co） was studied in N2/H2O atmosphere under simulated field condition by weighing method. The weight gain curves of kovar alloy oxidized at 1000℃ in N2 with different dew points were tested, and the results show that these oxidation kinetics obey parabolic rule. The composition and pattern of the oxides were analyzed by XRD and SEM. Thermodynamical calculations reveal that if kovar alloy is oxidized in N2/H2O atmosphere under simulated field condition, external air will infiltrate into the furnace, which increases the partial pressure of oxygen, and the presence of α-Fe2O3 in oxides surface is unavoidable. In the condition of a higher dew point and a longer oxidation time, the quantity of α-Fe2O3 formed will exceed that of Fe3O4.