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研究了表面涂覆CeO_2对Fe25Cr合金1100℃氧化行为影响。用热天平测定其氧化动力学,用声发射方法监测合金在氧化后冷却过程中氧化层的开裂剥落行为,并用SEM/EDS、EPMA等方法观察分析了氧化层的形貌、结构与成分。结果表明,表面涂覆CeO_2显著降低了Fe25Cr合金的氧化速率,并提高了氧化层在热应力作用下的抗剥落能力。研究发现了,表面涂覆CeO_2对富铁氧化物在外氧化层的形成起到抑制作用。此外还发现,经长时间氧化后,涂覆的CeO_2已进入Cr_2O_3层中。讨论了CeO_2的作用机制,认为CeO_2在Cr_2O_3层晶界偏聚,不仅阻碍了铬的扩散,更重要的是阻碍了铁向外扩散,从而抑制了铁氧化物的形成,增加了氧化层的保护作用。进一步对氧化层进行原子尺度的研究是必要的。
The effect of surface coating CeO_2 on the oxidation behavior of Fe25Cr alloy at 1100 ℃ was investigated. The oxidation kinetics of the alloy was measured by thermobalance and the spalling behavior of the oxide during cooling after oxidation was monitored by the acoustic emission method. The morphology, structure and composition of the oxide layer were observed and analyzed by SEM / EDS and EPMA. The results show that the surface coating CeO 2 significantly reduces the oxidation rate of Fe25Cr alloy and increases the anti-spalling ability of the oxide layer under thermal stress. The study found that surface-coated CeO 2 inhibited the formation of an extra oxide layer of iron-rich oxides. In addition, it was also found that after a long period of oxidation, the coated CeO 2 has entered the Cr 2 O 3 layer. The mechanism of CeO 2 is discussed. It is believed that the segregation of CeO 2 at the grain boundaries of Cr 2 O 3 layer not only hinders the diffusion of chromium, but more importantly hinders the outward diffusion of iron and thus inhibits the formation of iron oxide and increases the protection of oxide layer effect. Further study of the oxide layer atomic scale is necessary.