The Internal Stress Analysis And Polarization Simulation Of The Piezoelectric Ceramics

The influence of polarization and internal stress on properties of piezoelectric ceramics was researched. And the influence of residual stress on properties of nanocomposites also was studied.First we build up a theoretical model to analyze that the polarization and internal stress affect the properties of piezoelectric ceramics. The orientation distribution of domains and the piezoelectric coefficient of tetragonal ceramic were discussed under conditions of unidirectional polarization and scanning polarization. The results show that the orientation distribution of domains and the piezoelectric coefficient d33 is different with the increase of parameter of A （（d15+d31）/d33）. There are five cases of the orientation distribution of domains with scanning polarization but only one case with unidirectional polarization. The ratio of the d33 （scanning polarization）/d33 （unidirectional polarization） is increasing with the increase of the A. When the parameter of A tends to infinity, the ratio of d33 （scanning polarization）/d33 （unidirectional polarization） is 1.4271. Then the matrix-particle model explains of changes in Curie temperature and piezoelectric coefficient under residual stress influence. Using the above two theoretical model, the piezoelectric coefficient d33 of BT-ZrO2 and PZT-ZrO2 ceramic was investigated as a function of volume percentage of ZrO2.A theoretical model was established to investigate the intragranular particle residual stress in Al₂O₃–SiC nanocomposites. Using this model, we calculated the average compressive stress on the Al₂O₃ grain boundaries （GB） and the average tensile stress within Al₂O₃ grains caused by the SiC nanoparticles. The normal compressive stress strengthens the GBs and the average tensile stress weakens the grains. The model gives a reasonable interpretation for the strength changes in Al₂O₃–SiC nanocomposites with the amount of SiC particles.