不同操作条件下氧化铝烧结对致密化的影响

Nearly pure -alumina samples produced by uniaxial pressing were flash sintered under electrical fieldsranging from 500 V/cm to 1500 V/cm in experiments at constant heating rate. Sintering temperature sig-nificantly decreased with the applied E-field even down to ≈900?C at 1500 V/cm. The onset temperaturefor flash sintering can be successfully modelled as a function of the applied voltage. The sintering temper-ature is also shown to be strongly affected by the electrode materials used during the treatment: usingsilver or carbon electrodes the sintering temperature is about 300?C lower than when using platinumelectrodes. In addition, the bulk density and porosity of the sintered alumina ceramic correlate stronglywith the imposed current limit. Power dissipation was analysed before and during flash sintering; theactivation energy for conduction was calculated in both cases, indicating that the process is based onionic diffusion phenomena. Finally, we showed that during flash sintering the activation energy for con-duction decreases, suggesting the occurrence of physical or structural modifications induced by currentlocalization at the grain boundaries.