Microstructure and rheology of magnetic hybrid materials

该项目的目标是了解磁流变行为，即磁性杂化材料（MHM）在磁场中在多尺度水平上的粘性、粘弹性和弹性行为的变化。这就需要研究材料微观结构的变化与其材料性质的变化之间的关系。因此，该项目旨在填补微观结构和流变特性之间的空白，为优先计划中的理论工作组提供有关微观结构以及相应的磁场依赖材料特性的数据。关于微观结构变化与外部刺激对材料性能的调节之间的联系的实验和理论结果的结合，将为特定应用的定制磁杂化材料的合成提供新的方法。为此，该项目将结合磁流变学研究，即测量MHM在磁场中的粘弹性和弹性特性，并使用x射线显微断层扫描进行微观结构研究。MHM内部结构的层析检查主要关注外部磁场和机械载荷引起的结构变化。由于这些变化可以在单个粒子水平上检测到微米大小的粒子，即对于每个粒子的几何位置变化可以单独评估，因此各自的数据可以作为理论研究的基准。在实际项目阶段，我们打算重点研究磁场和机械载荷对样品的联合作用。这将为研究磁流变效应及其微观原因提供真正的多尺度实验方法。结合SPP内的理论研究，这将成为对此类效应更深层次的多尺度理解的基础。通过结合颗粒位置变化的层析数据和WG Auernhammer提供的颗粒附近矩阵变形数据，将有可能对模型进行更深入的验证。此外，流变学数据可为SPP中面向应用的群体提供原型设计所需的经验材料规律。

The goal of the project is the understanding of the magnetorheological behaviour, i.e. the change of the viscous, viscoelastic and elastic behaviour of magnetic hybrid materials (MHM) in a magnetic field on a multi scale level. This requires an investigation of the correlation between changes of the microscopic structure of the material and changes of its material properties. Therefore the project is intended to fill the gap between microstructural and rheological properties, providing the theoretically working groups within the priority programme with data concerning the microstructure as well as with the corresponding magnetic field dependent material properties. The combination of experimental and theoretical results concerning the connection between microstructural changes and an adjustment of material properties by external stimuli will enable new methods for synthesis for tailored magnetic hybrid materials for certain applications. For this purpose the project will combine magnetorheological investigations, i.e. measurements of viscoelastic and elastic properties of the MHM in a magnetic field, with microstructural investigations using X-ray micro tomography. The tomographic examination of the inner structure of the MHM focuses on changes of the structure induced by external magnetic fields and mechanical loads. Since these changes can be detected for micron sized particles on a single particle level, i.e. for each particle changes of geometrical position can be evaluated individually, respective data can be used as benchmark for theoretical investigations. In the actual project phase we intend to focus on combined action of magnetic fields and mechanical loads on the samples. This way it will become possible to gain real multi scale experimental approach for the investigation of magnetorheological effects and their microscopic reasons. In combination with theoretical investigations within the SPP this will become the basis for a deeper multi scale understanding of such effects. By combination of tomographic data for changes in particle position with data for deformation of the matrix in the vicinity of the particles by WG Auernhammer an even deeper validation of the models will become possible. Moreover the rheological data can be used to provide empirical material laws needed by the application oriented groups in the SPP for the design of prototypes.