稀土改性铸造Fe-24Cr-32Ni型耐热钢高温氧化行为的研究

Study on High Temperature Oxidation Behavior of Cast Fe-24Cr-32Ni Steel Modified by Rare Earth

通过增重法研究了稀土元素Y和Ce对Fe-24Cr-32Ni耐热钢高温氧化速率的影响。同时采用扫描电子显微镜(SEM),能谱仪(EDS)和X射线衍射仪(XRD)对耐热钢高温氧化层的结构和组成进行了分析。实验结果表明,在1 000℃温度下氧化100 h后,未添加稀土元素的试样单位面积氧化增重37.1 g/m^(2),添加0.18%Ce的试样增重量为34.5 g/m^(2),而添加0.20%Y的试样单位面积增重最小,仅为14.9 g/m^(2),说明稀土元素的加入有效提高耐热钢在1 000℃下的抗氧化性。通过对氧化膜的内部组成及结构分析可知,稀土元素可以促进氧化膜表面形成一层完整致密的尖晶石氧化物,促进氧化膜与基体界面处Si的内氧化物形成,增大氧化膜与基体的接触面积,提高氧化膜与基体的结合强度。

The effect of rare earth elements Y and Ce on the high-temperature oxidation rate of Fe-24Cr-32Ni heatresistant steel was studied by analysis of gain weight.At the same time,scanning electron microscope(SEM),energy spectrometer (EDS) and X-ray diffractometer (XRD) were used to analyze the structure and composition of the high temperature oxide layer of heat-resistant steel.The results show that the biggest mass gain of the sample without addition RE after 100 h oxidation at 1 000℃ was up to 37.1 g/m^(2).The sample with 0.18%Ce added is the second,about 34.5 g/m^(2).The sample with 0.20%Y addition is the smallest,only14.9 g/m^(2).This indicates that the addition of RE can effectively improve the oxidation resistance of heatresistant steel at 1 000℃.By analyzing the structure of the oxide scale,it could be inferred that RE could promote the formation of a complete and dense layer of spinel oxide on the surface of the oxide film.Further,an internal oxide with Si was formed at the interface between the oxide film and the substrate.The pinning effect increased the contact area between the oxide film and the substrate,increasing the contact area and the bonding strength.