Simulation Of Melting Process Of Al 2 O ₃ 2 2 O ₄ Eutectic Ceramics

The alumina-based eutectic ceramic is considered as the most promising candidate materials of aviation engines due to its excellent mechanical property and high temperature oxidation resistance. Compared with other eutectic ceramic preparation methods, the induction zone melting method can reach a higher temperature gradient, and can also prepare samples with regular shape. In order to optimize the parameters in the induction zone melting process for preparing eutectic ceramic and to shorten the test cycle, the zone melting process for preparing AhO₃/MgAl₂O₄ eutectic ceramics was simulated with finite element method. The main conclusions are as follows:Effect of the applied parameters on the zone melting process of the eutectic ceramic was analyzed. The results show that:With the increase of the coil turn’s number, the magnetic field intensity of the crystal growth system is increased and the distribution range is increased, the induced current density intensity increases correspondingly; With the increase of the current intensity, the magnetic field intensity of the crystal growth system is increased and the distribution range changes very little, the induced current density intensity increases obviously; With the increase of the current frequency, the magnetic field intensity and distribution range of the crystal growth system change very little, the induced current density intensity increases obviously and concentrates on the crucible surface. The increase of coil turn’s number, the current intensity and current frequency lead to an obvious increase of the maximum temperature and the heating power.Effect of the crucible speed on the zone melting process of the eutectic ceramic is analyzed. The results showed that:in the selected eutectic growth stages, the system desires the maximum heating power when the growth stage reaches 70%; with the increase of the crucible speed, the melt convection intensity increases and the fluid morphology has a significant change. The increase of the flow field intensity will promote the heat and mass transfer process in some extent and reduce growth interface depression degree obviously.Effect of the forced heat transfer on the zone melting process of the eutectic ceramic is analyzed. The results showed that:With the increase of the convective heat transfer coefficient, the required heating power increases in the zone melting process, a higher heating power is required in the low growth stage especially; with the increase of the convective heat transfer coefficient, the melt convection intensity increases and the fluid morphology has a change in some extent. The depression degree of the growth interface doesn’t decrease but increase instead. The depression degree increases significantly at the initial growth stage.