The influence of processing parameters and material composition on the piezoelectric, dielec- tric and mechanical properties of dome-shaped pie-zoelectric actuators.

Thick film (Pb ZrxTi1-x O3(0≤x≤1))-Epoxy) structures and three-phase (lead zirconate titanate ii displacements. To study the influence of the curing conditions, after the fabrication of the dome-shaped devices using datum fabrication methods, four different curing conditions were employed: curing on the hotplate at 75°C with air, curing in the vacuum chamber at room temperature, curing with the air at room temperature and curing in the furnace at 75°C with air. The influences of the mechanical stirring were also studied associated with all four aforementioned curing conditions. The timing of the poling step and the duration were also studied, in this study the poling process has happened simultaneously with the curing process during the first 0.5h, 1h and 2h. After the initial curing, the samples would have finished the whole curing time with the optimized curing conditions from previous study. The study of the material composition such adding the MWCNTs has also been carried out in this work. The three-phase (PZT-Epoxy-MWCNTs) 0-3-0 dome shaped composite devices were initially fabricated with the datum fabrication procedure to nar- row down the optimized volume fractions of the MWCNTs in the composite. And the updated method was employed to further study the optimized volume fractions of the MWCNTs. The volume fraction of PZT was fixed at 0.6, and the highest values for the longi- tudinal piezoelectric coefficient (@110Hz), effective dielectric constant (@2kHz), and dielectric loss (@2kHz), were 12.507 pC/N, 90.72 and 0.00185 respectively for the MWCNTS volume fraction equal to 0.13. The piezoelectric strain coefficient d33 for this dome structure was improved 13.7% compared to that previously reported value for a composite PZT-epoxy dome structure of similar structure and composition but have fab- ricated through the datum procedures. The sample morphology was examined with the aid of scanning electron microscopy (SEM) images and the material distribution was iii iii studied by energy dispersive x-ray spectroscopy (EDS). All samples were Corona poled allowed for higher poling voltages (45 kV/mm). It has been observed that adding the magnetic stirring step, cure initially with external electric field for 1h, and finished the whole curing in the furnace offered most optimized properties, parametricallywise. Piezoelectric strain coefficients and capacitance were measured @110Hz by Piezometer, and displacement of certain volume fractions of PZT were studied by Keyence interferometer. To better examine the polarization-electric field relation, P-E hysteresis loop were measured. Other dielectric properties such as conductance, resistance, and impedance spec- transverse increasing frequency were obtained by Hp impedance analyzer within the frequency range from 2kHz to 20Mhz. Investigation of composite structures such as these may lead to development of actuators with enhanced displacement and sensors with bet- ter sensitivity.Ph.D.Includes bibliographical referencesby Wanlin D