Thermal processing of multilayer PLZT actuators

Cofired multilayer actuators (MLAs) can suffer from reliability problems due to internal cracking, resulting from imperfections formed during binder extraction or sintering. Thermal processing methodology was developed to optimize manufacturing output of defect-free multilayer actuators. Rate-controlled thermogravimetry (RCT), in which furnace power is adjusted to maintain a constant specimen weight loss rates, was used for organic binder burnout in MLAs. The effectiveness of the various thermal schedules in eliminating MLA damage was determined through image analysis of depth profiles, ground perpendicular to the layers. The damage resulting from RCT schedules were compared to those produced using conventional temperature-controlled thermogravimetry (TCT). Specimens heat-treated with mass loss rates of 0.003 to 0.03 wt%/min showed fewer microstructural defects than all evaluated TCT schedules. Under RCT, furnace power was adjusted to mitigate the effects of rapid burnout of the multicomponent binder, which surged at specific temperature ranges. The effect of introducing a modified atmosphere of MLAs was also investigated using thermogravimetry in conjunction with mass spectrometry. (C) 2001 Kluwer Academic Publishers.