Ce对铁硅合金高温氧化行为的影响

Influence of Cerium on Oxidation Behavior of Fe-Si Alloys

通过光学显微镜、热重分析、X射线衍射和扫描电镜等研究了Ce对Fe-Si合金在900℃、0.1 MPa纯氧气中高温氧化行为的影响。结果表明,随着Ce含量的增加,Fe-Si合金及其氧化膜的晶粒尺寸明显降低,晶界浓度增加,这促进了合金元素和氧的"短路扩散"。在此过程中,"短路扩散"对合金氧化抗力产生的正影响大于负影响,添加Ce明显提高了Fe-Si合金的氧化抗力。过量的Ce优先参与氧化反应导致了Fe-3Si-5.0Ce较Fe-3Si-0.5Ce合金具有更大的氧化增重。添加Ce改变了合金的氧化机制,氧穿透氧化膜并与富Ce相优先发生氧化反应,产生"钉扎效应",可改善氧化膜的粘附性。

The effect of rare- earth Ce on high- temperature oxidation behavior of Fe- Si alloys at 900 ℃ in 0. 1 MPa flowing pure O2 has been investigated by means of optical microscope（ OM）,thermogravimetric analysis（ TGA）,X- ray diffraction（ XRD） and scan electron microscope（ SEM）. Results show that as the content of Ce increases,the grain size of Fe-Si alloy and its oxides decreases obviously,which makes the content of grain boundaries increase and promotes the short- path diffusion of the alloying elements and oxygen. In this process,the positive effect of the short- path diffusion on the oxidation behavior of the alloy is more obvious than negative effect,so the Ce addition improves the oxidation resistance of the Fe- 3Si alloys. Compared to Fe- 3Si- 0. 5Ce alloy,the excessive addition of Ce results in the more mass gain of Fe- 3Si- 5. 0Ce alloy for its preferential oxidation. The rare- earth Ce changes the oxidation mechanism of Fe- Si alloy. Oxygen penetrates the oxide scales and preferentially reacts with Ce- rich phases,which brings about the pinning effect and improves the adhesion of the oxide scales.