Experimental study of magnetic field driven properties of magnetic hybrid materials with complex internal interactions

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Classical magnetic hybrid materials contain either magnetically soft or magnetically hard particles. Thus, they show either an active magnetorheological effect or exhibit passive magnetorheological properties after magnetization of the magnetically hard particles. Within this research association of German and Russian project groups we combine magnetically hard and soft particles in an elastomeric matrix to provide a combination of active and passive magnetorheological properties. In this context, it is the central goal of the research association to synthesize tailored magnetic hybrid materials for sensor applications based on a detailed microscopic understanding of the material properties. Within the subproject described here, we will continue a study of the magnetic field driven properties of magnetic hybrid materials. In focus of the working program will be elastic magnetic hybrid materials based on magnetically hard and soft particles, as well as mixtures of them. After completion of the methodical studies regarding diverse experimental techniques in the first funding period, our work on these materials in the second phase will be focused on specific aspects of their behavior. In particular, a detailed study of the influence of the particles’ morphology on the magneto-mechanical properties of the composites will be carried out. Results obtained in the first phase emphasize two different physical processes, which are responsible for a distinctive magnetorheological effect: rotation/orientation of particles and structuring of particles inside an elastic matrix. Therefore, in order to distinguish between these processes inside the matrix, samples of hybrid materials based on particles of spherical and irregular morphology of both magnetically hard and soft types will be considered. Another goal of the subproject will be a study of the composite’s response under certainly defined preloading conditions. To date, this is a rather neglected aspect of magnetic hybrid materials. However, this topic is of particular importance for technical applications, when a specimen is integrated in a device structure under preloading condition. Moreover, we will perform a study regarding the anisotropy of the viscoelastic response and an evaluation of the magnetodeformational effect for hybrid magnetic materials with a magnetically hard and complex filler. Complementary to preloading conditions, these issues are as well highly relevant for technical applications. A close cooperation with other working groups of the research association will allow us to find appropriate interpretations of the experimental results. In total, we expect that the project will provide detailed information about the relation between microstructural changes and macroscopic properties of the magnetic hybrid materials. This information will provide the basis for a prediction of certain material properties, which can be achieved by respective changes in composition of the material.