• Jian Wang

      Articles written in Bulletin of Materials Science

    • Effect of annealing process of iron powder on magnetic properties and losses of motor cores

      Fuzheng Yin Haibo Yang Jianjun Tian De-An Pan Jian Wang Shengen Zhang

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      Iron powder magnetic cores are used as soft magnetic rotors, in micro special motors such as BS brake motors, refrigerator compressor motors and brushless servo motors. Heat treatment of iron powder played an important role in the magnetic properties and loss of the motor cores. After the annealing process, the cracks and the pores on the surface of the powder decreased which in turn decreased the micro-hardness. The Vickers-hardness of the powder decreased from 50–42, while the resistance of the cores increased by 87% after annealing at 400°C for 30 min. The amplitude permeability and magnetic loss of the cores reached the maximum and minimum values, respectively. The magnetic loss of the cores was separated into hysteresis loss and eddy current loss by Stoppels Method which were decreased by the annealing process.

    • Rapid heating effects on grain-size, texture and magnetic properties of 3% Si non-oriented electrical steel

      Jian Wang Jun Li Xinfeng Wang Xiaochuan Mi Shengen Zhang

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      The rapid heating effects on the microstructure, texture and magnetic properties of 3% Si nonoriented electrical steel has been investigated through optical microscopy, X-ray diffraction and Epstein frame. The results show that recrystallized grains were refined with increased heating rate, caused by the nucleation rate increase, which is faster than the growth rate due to rapid hearting. With the heating rate increase, the characteristic {111} recrystallization fibre of cold-rolled steel was depressed, but the beneficial $\langle$001$\rangle$//RD and $\langle$001$\rangle$//ND fibres were significantly strengthened. Although the grain-size decreases with heating rate increasing, the optimal magnetic properties can also be obtained through the recrystallized grain-size and texture optimization by rapid heating. In this research, we find the magnetic properties optimization can be obtained when annealed with 100°C/s heating rate: the core loss ($P_{1.5/50}$) decrease 13% and the magnetic induction ($B_{50}$) increase 3%.

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