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Thesis Advisor肖骅昭
Degree Grantor中国科学院研究生院
Abstract本文在总结前人工作的基础上,较为系统地研究了在600-1100 ℃之间铁的氧化物还原后的结构与形态。实验主要对象是化学纯试剂铁的氧化物,其中包括粉体压块和磁铁矿单晶体,并辅之以实际铁精矿球团。通过用扫描电镜和岩矿相显微镜对还原后试样的观察,发现了金属铁两种结构的形成条件,添加阳离子对于铁晶须生长的影响,铁的各个氧化态:Fe_20_3,Fe_30_4,Fe_(1-x)_0序列还原后的形态特征,最后应用晶体或核理论,界面稳定性理论对于金属铁晶须的形成予以解释。
Other AbstractOn the basis of the research works of predecessors, the present paper describes the structures and morphological chang of iron oxides at various reducing stage by CO in the temperature range of 600 ℃ to 1100 ℃. The experimental samples were principally chemical pure compacts of iron oxide powder, in addition to single crystals of Fe_30_4. For the practical purpose, some iron concentrate pellets were used. From the observation of samples under SEM and optical microscope, it follows that: 1. The structure and morphology of reduced samples are related to crystalline state of original samples. The better the crystalline state, the smaller the possibility of growth of iron whiskers is. 2. The growth of iron whiskers occurs only in temperature range of 600 ℃ to 900 ℃. 3. If compounds of other cations which have same lattice structure as wustite dissolved in wustite, some new phase will be produced. The new phases formed with relation to GaO will promote the growth of iron whisker, and those new phases with relation to MgO will suppress the growth of iron whisker. BeO, SrO, TiO_2, V_2O_5, Gr_2O_3, MnO_2, GoO, NiO, GuO, Zno, Al_2O_3, SiO_2, SnO_2 and PbO_2 have not any obvious effects on the growth of iron whisker. The cation radius of additives is not a influence fator upon the growth of iron whisker. 4. In the course of reduction, no obvious morphological changes between iron oxides: Fe_2O_3, Fe_3O_4 and Fe_1-x_0 were observed. When Fe_2O_3 is reduced to Fe_3O_4, the latter occures in the form of spot crystals, whereas the transformation from Fe_3O_4 to Fe_1-x_0 is a process of parallel front development. 5. Iron phase is produced mostly in topochemical manner. The growth of iron whisker is a special situation. But in some cases these two manner may occur simultaneously. 6. The formation of iron whisker is an intrinsic phenomenon which may occur whether or not the sample is subject to preoxidation treatment. From the theoretical consideration, the theory of nucleation and stability of interface by W. W. Mullins and R. F. Sekerka is applied to explain the growth of iron whisker. Following results were obtained: 1. The growth of iron whisker is resulted in disturbance deformation of iron spheric nuclei which is caused by uneven diffusion of iron atoms. The rate of increase of the disturbance deformation for time is direct proportional to surface tension of iron spheric nuclei and inverse proportional to temperature of reduction. 2. Only when the radius of iron spheric nuclei is small enough, may the growth of iron whisker possibly occur.
Document Type学位论文
Recommended Citation
GB/T 7714
余奥涵. 铁的氧化物在还原过程中的结构与形态[D]. 中国科学院研究生院,1988.
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