Effect of binder materials on mechanical response of FeCoPSi-based bonded magnets

This study aims to investigate the mechanical properties of elastomer-bonded magnets in which nitrile-butadiene rubber (NBR) and chlorinated polyethylene (CPE) are employed as binders for ferromagnetic powders. The work is part of a broader research effort focused on developing rare-earth-free magnets with intermediate performance between ferrites and NdFeB, capable of replacing NdFeB magnets in automotive applications. Within this framework, an innovative FeCoPSi powder is presented and compared with conventional ferrite. The mechanical behaviour of these bonded magnets is analysed through tensile tests, enabling a comparison between the two elastomers (NBR and CPE) and, subsequently, between the two magnetic powders. The influence of powder particle size on mechanical performance is also evaluated, as some FeCoPSi batches present a coarser granulometry while others a finer one. The results show that, for the same powder, CPE-based samples display greater stiffness and achieve higher values for most mechanical properties compared to the corresponding NBR-based samples. Furthermore, particle size plays a crucial role, as batches with finer granulometry achieve superior mechanical performance owing to improved cohesion between the matrix and the filler.