Study On NdFeB/Thermosetting Resin Matrix Magnetic Composites

NdFeB magnetic powders and modified polyimide were used in the preparation of bonded NdFeB magnets. The effects of technology on the properties of bonded magnets were studied. The masterbatchs of NdFeB/phenolic resin (PF) were prepared by in-situ polymerization and in situ graft polymerization respectively. Furthermore the bonded magnets were prepared. The masterbatch structure and graft characteristic were investigated by using infrared (IR) and thermogravimetric analysis (TGA). The composite resins of polyimide-epoxide resin (PI/EP) and phenolic-epoxide resin (PF/EP) were used as the binders to prepare bonded NdFeB magnets. The magnetic and mechanical properties of bonded magnets were studied. These methods haven't been reported.The results indicated as follows: 1) The proportion of NdFeB magnetic powders in coarse powders was 33% and 67% in fine powders. The quantities of coupling agent and binder were respectively 0.9% and 3.2% in magnetic powder mass. The proper pressure was 600 MPa. And by using modified polyimide the bonded NdFeB magnet with good properties was obtained. 2) In the process of in-situ polymerization phenolic resin inclined to polymerize on the surface of NdFeB magnetic powders to form NdFeB coated by phenolic resin. And the sea-island structure was formed. By comparison of overall properties of bonded magnets prepared by three techniques, it was found that using NdFeB/PF masterbatch powder as the binder could produce bonded magnets with better properties. 3) In the process of in-situ graft polymerization NdFeB magnetic powders entered...