摘要
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。
Investigation has been made of effect of superficially applied ceria on oxidation behavior of Fe25Cr alloy at 1100℃. The oxidation kinetics measurements has been carried out in thermobalance. Acoustic emission technique has been used to monitor the cracking and spalling hehavior of the oxide scale during cooling after oxidation for 20 hours. The morphology, structure and composition of the oxide scale were examined by SEM / EDS, optical metallography and EPMA. It has been shown that the oxidation rate of the alloy was decreased markedly and the coherence and adherence of the oxide scale was improved greatly by the superficially applied ceria. The cross section EPMA examination demonstrated that the formation of iron rich oxide at the outer surface of the scale was inhibited after oxidation for 20 hours by the applied ceria. SEM / EDS and EPMA analysis revealed that the applied ceria has been dissolved into the scale after 20 hours oxidation. It is believed that the ceria plas a role by segregating at grain boundary of the scale. This segregation not only affects the diffusion of Cr but more importantly decreases the outward diffusion of Fe and thus inhibits the iron rich oxide formation. A further study of the oxide scale on atomic scale by HREM is proposed to illustrate the role of ceria playing.
出处
《腐蚀科学与防护技术》
CAS
CSCD
1992年第4期289-294,共6页
Corrosion Science and Protection Technology
基金
国家自然科学基金
国家高技术新材料领域专家委员会
关键词
高温氧化
涂覆
CEO2
Fe25Cr合金
Oxidation
oxide scale
composition
superficially applied ceria
Fe25Cr alloy
