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以高纯钼和高纯石墨为发热体材料,研究了电磁感应加热条件下发热体中磁场强度和磁场分布的情况。模拟计算表明,高的电源频率使发热体表面涡流密度大幅增加,加热能量集中且发热体中的感应磁场强度较低,磁场最大值在距离发热体下端3 mm处;随着发热体厚度由3 mm增加到9 mm,磁场屏蔽效果明显增强;高纯钼在较低温度下其电阻率小于高纯石墨,在1400~1600℃附近钼的电阻率急剧增加,该温度下石墨发热体屏蔽掉了74.7%的磁场,而钼发热体仅屏蔽了54.2%的磁场。电磁感应加热石墨发热体在TiAl合金籽晶法定向凝固过程中获得了400 K/cm温度梯度和良好的定向全片层组织。
The high-purity molybdenum and high-purity graphite are used as heating materials, and the magnetic field intensity and magnetic field distribution in heating element under electromagnetic induction heating are studied. The simulation results show that the high power frequency increases the eddy current density on the surface of the heating element, the heating energy is concentrated and the induced magnetic field in the heating element is low, and the maximum magnetic field is 3 mm away from the lower end of the heating element. mm increase to 9 mm, the magnetic field shielding effect was significantly enhanced; high-purity molybdenum at lower temperatures its resistivity is less than high-purity graphite, near 1400 ~ 1600 ℃ molybdenum resistivity increased sharply, the temperature of the graphite heating body shield 74.7% of the magnetic field, while the molybdenum heating element shielded only 54.2% of the magnetic field. Electromagnetic induction heating graphite heating element in the TiAl alloy seed crystal directional solidification process to obtain a 400 K / cm temperature gradient and good orientation entire sheet organization.