Abstract: The method of fractional precipitation on seeds is used to manufacture calcined additive powders.The properties of the powders are compared with those prepared by three other methods.It was observed that when the sediments were dried by the“half.dry”method via calcination in the range of 600 to 650℃. The calcined powders of the additives obtained have either no agglomeration or little agglomeration of the particles.The influence of the additive powders on spray dried granules and their forming are also studied.Eventually ZnO varistors with a voltage gradient of 2.6kV/cm and an energy handling ca· pability of 270J/cms are achieved.

Key words: ZnO varistors, fractional precipitation, voltage gradient, energy absorption