Effect of Curing time and Poling Field for Piezoelectric Properties of 0-3 Type Slag Cement and Fly Ash Cement Piezoelectric Composites
| Autor: | Chang-Keng Chiang, 姜長庚 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 In this study, 0-3 cement piezoelectric composites containing slag and fly ash are investigated. Cement piezoelectric composites consist of 50% PZT as inclusion and 50% cement binder as matrix by volume. Cement is replaced by slag or fly ash from 10% to 50% in the binder. Specimen was formed by a compressive stress of 80MPa, cured in the water with 90℃ for 7 days, 28 days and 56 days, respectively, and then polarized in 150℃ silicon oil bath for 30 minutes, in which three poling fields with 0.5kV/mm, 1kV/mm and 1.5kV/mm are applied. We examine microstructure and piezoelectric properties of the composite affected by curing time and poling field. Experimental results show that surface pores of PP composite gradually reduce with increasing slag, but only with fly ash less than 20% have the similar trend. The differences of hydration products for slag and fly ash less than 20% are small. When the replacement is greater than 20%, hydration products of slag are richer than those of fly ash. For cement piezoelectric composites prior to the polarization, the increase of slag and fly ash replacement induces high capacitance, relative dielectric constant and dielectric loss, compared with PP composite. However, increasing curing time will diminish capacitance, relative dielectric constant and dielectric loss except for SL50. Low dielectric loss of specimen shortened trigger time of polarization. Specimen with dielectric loss less than 0.73 is easy to polarize successfully. Piezoelectric properties of specimen will be found after the polarization. The values of piezoelectric properties except for electromechanical coupling factor have high fluctuation at early age, for example less than 30 days, and gradually become steady after 60 days. It seems that curing time has less efficient to piezoelectric properties. To increase piezoelectric properties, poling voltage is more effective. While voltage increases from 0.5 to 1.5 kV/mm, the enhancement for piezoelectric strain constant, piezoelectric voltage constant and electromechanical coupling factor is 23.4%~54.7%, 36.9%~74.7% and 1.3%~3.6%, respectively. On the contrary, capacitance and relative dielectric constant reduce with poling voltage. 20% replacement of slag and fly ash is the optimum contents to increase piezoelectric strain constant of 21.93% and 20.37%, respectively. Similarly, piezoelectric voltage constant for slag and fly ash also has 15.41% and 14.91% increment in turn. Fly ash is a better replacement than slag to increase electromechanical coupling factor. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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