Papers by Author: Z.G. Su

Abstract: Degradation aging of BaTiO3 microwave ceramic capacitors for EMI applications at highvoltage, AC 10kV, was focused in this paper. Electric performances of the ceramic capacitors were systematically evaluated with thermal shock (5 cycles of –30 °C for 1 h and then 125°C for 1 h), damp heat (100% RH at 40°C for 500 h), and, endurance at high temperature (DC 10 kV at 100°C for 500 h). High reliability for the ceramic capacitor was obtained with optimal ceramic composition, sintering temperature, epoxy resin, curing agent and additives, which was satisfied with practical microwave technologies.

Abstract: Gelcasting is a novel ceramic forming process for fabricating products of complex-shaped ceramics. In this contribution, the gelcasting process is applied to manufacture green body of microwave ceramic components for resonators, oscillators and antennas. Calcined powders, dispersant and organic monomers are mixed together by ball-milling to acquire high solid loading slurry with low viscosity. After addition of initiator and catalyst, the slurry is cast into a non-pours mold and then polymerized. The slurry is thus solidified in situ and the green bodies with the desired shapes are obtained. The dried body is rather strong and can be machined so as to get more precise or complex-shaped components. Then the green bodies are sintered at high temperature. The microwave properties (εr, Q, τf) and microstructures of the ceramics prepared by gelcasting are compared with those of die-pressed ones.