Analysis of physical and magnetic properties of composite NdFeB bind with polyvinyl alcohol

Abstract

The composite magnet NdFeB has been made using magnetic powder MQP-B and polyvinyl alcohol (PVA) as the binder. The mixing compositions of raw materials used are: 95 wt% NdFeB - 5 wt% PVA, 92.5 wt% NdFeB - 7.5 wt% PVA, 90 wt.% NdFeB - 10 wt% PVA, and 87.5 wt% NdFeB - 12.5 wt% PVA. Both raw materials are weighed according to the composition, and then mixed until homogeneous. Furthermore, pellet forming was made using dry pressing at 50 kgf/cm2 pressures and continued with drying at 100 °C and 10 mmbar for 4 hours. The characterization includes bulk density, hardness, compressive strength measurements, and magnetic properties testing. The characterization results show that the optimal composition of binder PVA is achieved at 5-7.5 wt% NdFeB composite magnet with following properties: bulk density = 5.21-5.25 g/cm3, hardness = 302.17 - 304.32 Hv, compressive strength = 25.17-3.17 kgf/cm2, magnetic flux = 1150-1170 Gauss, remanence = 70.90-74.97 emu/g or 4.7-5.0 kGauss, coercivity = 8.68-8.76 kOe, and energy product = 2.89-3.04 MgOe.