Aqueous tape casting of ZnO varistor ceramics with PVA as binder and their properties

ZnO varistor ceramic tapes were prepared by aqueous tape casting with polyvinyl alcohol as the binder.The effects of components on the properties of the slurry for aqueous tape casting were investigated with particle size analyzer,viscometer and dynamic mechanical analyzer.The microstructure and phase composition of the prepared tapes were studied with environmental scanning electron microscope and X-ray diffractometer.The results show that when the mass ratio of ceramic power to deionized water to dispersant to binder to plasticizer to surfactant is 100 : 84.6 : 1 : 6 : 5.4 : 3,the tape shows a homogeneous microstructure with no defect.Moreover,after sintering at 900 ℃,the tape exhibits excellent electrical properties: voltage gradient E1mA = 112.4 V/mm,nonlinear coefficient ? = 34.6,leakage current density JL = 0.5×10–6 A/cm2.