Properties of High Density Magnetic Composite (HDMC) by Warm Compaction Using Die Wall Lubrication

摘要

Powder magnetic cores (or dust cores and soft magnetic composites (SMC)) are candidate materials for new type motor cores, because they have good points as follows; isotropic magnetic properties, high electric resistivity and easy recycling. However, the materials are hardly used for motors, because both their magnetic flux density and their strength are smaller than those of laminated steel. The small magnetic flux density and strength were caused by small green density. In order to increase the green density, it needs reduction the admixed lubricant and high-pressure compaction. We developed a new warm compaction using die wall lubrication with lithium stearate. According to the method, very high-density compact could be fabricated without scoring. In this instance a raw material was Somaloy500 without resin, the powder magnetic core compacted at 1176 MPa with heat treatment at 673K had properties as follows; d = 7.77Mg/m~3, mu _m = 1000, B_(2k) = 1.41 T, B_(5k) = 1.61 T, B_(10k) = 1.80T, _bH_c=300 A/m, rho = 4 mu OMEGA m, TRS = 210MPa, sigma _(max) = 150 MPa, and in case of B_m = 1T and f = 400 Hz, Pc = 900k W/m~3, Ph = 350k W/m~3, Pe = 550k W/m~3.