Effects of processing parameters on density and electric properties of electric ceramic compacted by low-voltage electromagnetic compaction

In this research, low-voltage electromagnetic compaction (EMC) was applied to compact TiO2 and PZT powders in the indirect way. After selecting the appropriate processing parameters, TiO2 and PZT ceramics of higher density and better electrical properties were produced compared with traditional static compaction. The microstructures of two ceramics produced by two above-mentioned methods respectively show that, the average grain size of TiO2 and PZT compacted by low-voltage EMC are about 8 μm and 4 μm which are smaller than that by static compaction respectively (15 μm and 7 μm) under the same sintered condition. Discharge voltage and charge capacitance are important factors to the green density and sintered part's density of each ceramics. Meanwhile, TiO2 and PZT have their own discharge voltage range (700–1100 V for TiO2 and 600–1000 V for PZT), during which each ceramic powder could be pressed effectively. With the same condition of charge capacitance, as the discharge voltage increases toward a peak value, the green density and sintered part's density increase, then tend to decrease after that peak value. The green density and sintered part's density of each ceramic increase and the above peak discharge voltage decrease slightly, as charge capacitance enlarges in the range investigated. In addition, effects of pancake coil turns and field shaper structure on the ceramic density were investigated. In most of cases investigated, the higher the ceramic part's density, the better the dielectric constants of TiO2 parts and the piezoelectric constants of PZT parts.