Fabrication And Characterization Of Macro Fiber Composite Actuators

In this work,0.55Pb(Ni_1/3Nb_2/3)O₃-0.45Pb(Ti_0.7Zr_0.3)O₃（0.55PNN-0.45PZT） and0.4Pb(Zn_1/3Nb_2/3)O₃-0.6Pb(Zr_0.49Ti_0.51)O₃（0.4PZN-0.6PZT） piezoelectric ceramics were fabricated bytraditional solid-state reaction method, respectively. They are typical Pb-basic relaxor piezoelectricceramics. Both of their compositions are near the morphotropic phase boundary （MPB）. Themicrostructures and electrical performances of the ceramics influenced by sintering temperature wereinvestigated. Meanwhile,0.4PZN-0.6PZT piezoelectric ceramics were fabricated by tape-castingprocess, and macro fiber composite actuators were prepared by arrangement-casting method andincision-padding method.Firstly,0.55Pb(Ni_1/3Nb_2/3)O₃-0.45Pb(Ti_0.7Zr_0.3)O₃piezoelectric ceramics prepared byconventional solid-state reaction method possessed good piezoelectric and dielectric properties, withthe composition near the morphotropic phase boundary （MPB）. The results showed that the ceramicssintered at1250oC had the best integrated performances, Tc=106℃, ρ=7.77g/cm³, d₃₃=920pC/N, ε_r=7.41×103, k_p=0.62, tanδ=0.024, P_r=27.4μC/cm2, Ec=4.2kV/cm.Secondly,0.4Pb(Zn_1/3Nb_2/3)O₃-0.6Pb(Zr_0.49Ti_0.51)O₃piezoelectric ceramics prepared byconventional solid-state reaction method also possessed good piezoelectric and dielectric properties,with the composition near the morphotropic phase boundary （MPB）. It was found that the degree ofdiffuseness （γ） decreased with the increase in sintering temperature from1175°C to1225°C, therebyindicating that the dielectric relaxor behavior weakened, however, at high sintering temperaturesabove1225°C, γ was subsequently increased. The ceramics sintered at1225°C had the best electricproperties: ε_r=2651, tanδ=0.016, d₃₃=536pC/N, k_p=0.59, P_r=33.8C/cm2, and Ec=9.2kV/cm,which corresponded to the tetragonal phase content Vt=73%.Finally, The structure of piezoceramic fiber composite actuator was designed, includinginterdigitated electrode plates, binder and piezoceramic fiber composite layer. The flexible, planarpiezoceramic fiber composite actuators were prepared by arrangement-casting method andincision-padding method. The electrical and mechanical properties of the0.4PZN-0.6PZT ceramicswere tested. Piezoelectric properties of piezoceramic fiber composite were estimated by iso-strainmixing formulas. The strain properties of the actuator were tested using dynamic response systembased on LabVIEW. The piezoelectric constant d₃₃and elastic compliance coefficient s33of the0.4PZN-0.6PZT ceramics were found to be520pC·N^-1and20.5×10-12m2·N^-1, respectively. Theory of piezoelectric constantsd33andd31of piezoceramic fiber composite were509and-156pC·N^-1,respectively. It was found that four sets of MFC drive device generated the largest strain in a1Hzfrequency. In the case of other conditions were the same, the smaller its tf, the greater the strain of thesample. The four groups of MFC longitudinal strain amplitude were180με,148με,78με and15με inthe800V,1Hz. Their longitudinal extensions were6.48μm,5.33cm,2.81μm and0.54μm, respectively.First group MFC drive had strong electromechanical conversion ability.