Diffusion-controlled processes in polycrystalline ceria:Combined effect of electrical field and mechanical loading

多晶二氧化铈中的扩散控制过程：电场和机械载荷的综合效应

• 批准号: 319339707
• 负责人: Professor Roger De Souza, Ph.D.
• 金额: --
• 依托单位: Lehrstuhl für Physikalische Chemie I
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/319339707?language=en
• 关键词: Diffusion; controlled; processes; polycrystalline; ceria

In this follow-up project, the existence and role of field-induced local field and temperature gradients as well as changes in grain boundaries and space-charge layers shall be systematically investigated. Furthermore, we extend the focus to the influence of the frequency of applied AC fields, potential benefit for enhanced creep behaviour of sintered bodies (superplasticity) and during constrained sintering of layers.The following more specific questions shall be addressed:• What is the contribution of direct field effects (for example change of oxygen vacancy concentration modifying diffusivity and conductivity) compared to local induced temperature gradients?• Are the field-induced changes in the structure of CeO2 grain boundaries persistent over the lifetime of a ceramic part or do they disappear rapidly after switching off electrical loading?• Which frequencies of AC fields do maximise the influence of the electric field on sintering and diffusional creep? How is it related to the material properties?• How much is creep behaviour affected by an electrical field/current? Can superplasticity be induced? • Can the observed advantages of field assisted sintering be used during constrained sintering of layered compounds?

在这一后续项目中，将系统地研究场致局域场和温度梯度的存在和作用，以及晶界和空间电荷层的变化。此外，我们将重点扩展到外加交流电场的频率对烧结体蠕变行为(超塑性)的影响，以及在层的约束烧结过程中的潜在益处。需要解决以下更具体的问题：·与局部感应温度梯度相比，直接电场效应(例如改变氧空位浓度改变扩散系数和电导率)的贡献是什么？·电场引起的CeO2晶界结构变化是在陶瓷部件的整个寿命期间持续的，还是在切断电力加载后迅速消失？·哪些频率的交流电场能够最大限度地增加电场对烧结和扩散蠕变的影响？它与材料性能有何关系？·电场/电流对蠕变行为的影响有多大？可以诱导超塑性吗？·在层状化合物的约束烧结过程中，能否利用所观察到的场助烧结优势？