Two-Stage De-binding for Cu Electrode Application to PZT-PZNN Multilayer Actuator

To fabricate a multilayer actuator by applying Cu paste by the tape casting method, the correlation between the amount of residual carbon from the de-binding process and the sinterability was reviewed and the effect of the former on the piezoelectric properties was observed. The Cu electrode must be fired in a reducing atmosphere to prevent oxidation, but a preliminary de-binding process was performed in an oxidizing atmosphere for effective binder burn-out. After performing a preliminary de-binding process for 24 h in an oxidizing atmosphere, the residual carbon amount was measured with a variation of the main de-binding temperatures in a reducing atmosphere to find the optimal binder burn-out process conditions. As a result of co-firing the specimens (obtained from the two-stage de-binding) in a reducing atmosphere at 900 °C, the maximum sintered density was 7.65 g/cm³. When the final residual carbon amount increased from 0.02 to 0.09 wt%, the capacitance value showed a tendency to decrease from 23.16 to 12.26 nF, and the electrical resistance value increased from 0.2 to 0.8 Ω.