| Microwave sintering is widely used as a new special ceramic sintering technology in recent years. Owing to the many advantages of microwave sintering such as overall heating, fast heating up, it has been a hot technology in ceramic sintering area. One of the main factors in microwave sintering is heating uniformity of material sintering. So it is beneficial to the electromagnetic field distribution of sintering cavity.When unloaded or Alumina cylinder samples loaded, three-dimensional electromagnetic simulation software HFSS is used to simulate the electromagnetic field distribution in the cavity so that the best position for sintering samples can be found. Firstly, the height of the samples is set so that the most suitable radius, 30 mm, can be found out. Secondly, the height of the sample ranges from 10 mm to 100 mm for getting the best height for sintering. The height is confirmed as 77 mm. The radius and height of the sample is respectively 30 mm and 77 mm.Using the results of the electromagnetic field, ANSYS software is used to simulate the temperature field. The temperature rises 30? when electromagnetic field changes in one cycle time.Then, the result of the temperature field is put into LABVIEW software to find out the regulation of Alumina ?r and tan?. The conclusion is: At the steady-state thermal analysis, when the temperature rises from 20? to 800?, ?r rises at first, then decreases. tan d increases slowly under the critical temperature range but rises fast above the critical temperature. So the critical temperature range is between 830 ?and 860?. At the transient thermal analysis, the values of ?r and tan? is simulated in 300 seconds from 800?. Both ?r and tan? generates a mutated value at 833?. So the critical temperature is confirmed as 833?.Finally, the experiments are done to compare with the results of the simulation. the experiments' data can verify the simulation results. |
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