Control of non-equilibrium microstructure and function of oxide scales formed in high temperature oxidation of metalic materials for high efficiency energy comversion

（1）高温氧化生长膜中空洞形成的定量预测本文提出了计算氧化生长膜中化学势分布、离子通量及其发散度的方程。结果表明，发散度是评价空洞形成的较好指标。铁高温氧化形成的磁铁矿氧化膜实验证实了该方法的有效性。（2）固体氧化物燃料电池（SOFC）连接件用铁素体Fe-Cr合金的高温氧化及氧化膜的导电性模拟SOFC的工作条件，在1073 K下对Fe-16 Cr合金进行了高温氧化实验，实验中试样分别暴露于空气和H_2O（97%）和H_2（3%）的混合气体中。两侧形成连续的Cr2 O3保护膜。生长速率非常相似，表明在两种情况下主要缺陷是Cr的间隙离子。 ...更多信息 氧势分布阐明了在尺度上几乎整个区域的氧势都是低的。这一事实预示了Cr_2O_3氧化皮电导率高的原因。施加的外部电流延缓了阴极上的Cr2 O3的生长速率，并且增强了阳极上的Cr2 O3的生长速率。提出了外电流作用下水垢生长速率的估算公式，并对长期暴露下的水垢生长速率进行了预测。（3）微观结构发展的控制和尺度功能的设计本课题的主要内容如下：（1）利用氧势与组元离子扩散系数的函数关系，可以定量预测微观结构的发展。（2）为了控制微结构，需要设计扩散系数。适当的掺杂是微结构设计的可能性。（3）化学势分布和离子通量发散度的计算对微结构控制和尺度功能设计具有重要意义。少

(1)Quantitative prediction of void formation in a growing scales in high temperature oxidationEquations have been proposed for evaluation of chemical potential distribution, ionic fluxes and its divergence in a growing oxide scales. The divergence was proved to be the good measure for evaluating the void formation. The validity was experimentally confirmed in magnetite scales formed in high temperature oxidation of iron.(2)High temperature oxidation of ferritiv Fe-Cr alloys for interconnects in solid oxide fuel cell (SOFC) and electrical conductivity of the oxide scale.Simulating the operation condition of SOFC, high temperature oxidation of Fe-16Cr alloys was conducted in the dual atmosphere, in which specimens were exposed air for the cathode and the mixture of H2O (97%) and H2 (3%) at 1073 K. The continuous protective Cr2O3 scales were formed on both sides. The growth rates were quite similar, indicating the major defect was interstitial ion of Cr in two cases.The estimation of the … More oxygen potential distribution clarified that the oxygen potential is low almost the whole region in scales. This fact predicted the reason why the electrical conductivity of the Cr2O3 scales were high. Applied external currents retarded the growth rate of Cr203 on the cathode and enhanced it on the anode. The equations were proposed for evaluating the scale growth rate under the external current and the equations predicted the growth rate in the long term exposures.(3)Control of microstructure development and design of the function of the scales.The summary of this project is the following(1)The quantitative prediction of microstructure development is possible with diffusion coefficients of constituent ions as a function of oxygen potential.(2)For controlling microstructure, it is dispensable to design the diffusivity. The appropriate doping is an possibility for the design of the microstructure.(3)The evaluation of chemical potential distribution and divergences of ionic fluxes is very powerful for controlling microstructures and designing the function of scales. Less