Development of Polymer Bonded Magnets with Enhanced Magnetic Properties for High Temperature and Aggressive Environments

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9712688 Otaigbe This GOALI research program investigates the role of magnetic particle morphology, concentration and distribution on the processing, and magnetization behavior of bonded magnets. The heat resistance of bonded magnets can be improved by selecting heat resistant binders and high temperature polymers. However, the use of high temperature engineering polymers is limited by the oxidizing behavior of the magnetic alloy powders at the polymer processing temperatures. Thermal stability of the rare earth magnetic powders at the desired temperature ranges can be improved by suitable surface treatments. The energy product can be improved by optimizing the fraction of magnetic powders and careful control of the particle morphology and particle size distribution. A fundamental understanding of the interaction between the polymer matrix and magnetic powders is essential in developing suitable powder coatings to improve the thermal stability of the powders. Surface coatings which are chemically compatible with the polymer binder are investigated. The study focuses on evaluating various types of polymer binders, such as polyphenylene sulphide (PPS) and liquid crystal polymers (LCP). In addition the rheological behavior of the polymer binder/powder mixtures is studied for improving processability. Based on the experimental data obtained, theoretical models are developed to predict the optimal concentrations and distributions of magnetic powders. The project involves a collaboration between Iowa State University and Arnold Engineering Company, a leading manufacturer of magnetic materials in the United States. The graduate student will spend three summer months at Arnold Engineering assisting in elevated temperature testing of the samples. This project is jointly funded by the MPS Office of Multidisciplinary Activities and the Division of Materials Research. %%% Polymer bonded magnets are widely being used in many automotive and nonautomotive appli cations. A need exists to develop bonded magnets with higher energy products that can withstand operating temperatures of at least 180 C and higher. A key issue is the identification of suitable magnetic powders and polymer matrices which can perform satisfactorily at the desired higher temperatures. ***