Gelcasting Of PZT Piezoelectric Ceramics And Preparation Of Composites

Acrylamide-N,N’-methylenebisacrylamide(AM-MBAM)system can be more easily controlled during gelcasting due to its excellent gelation properties.In the article,this system was used to prepare with PZT ceramics.Firstly,the pure gels were prepared.The influences of AM concentration and the ratio of AM and MBAM on gel structure and breakage elongation were investigated.During the process of free radical polymerization,the influences of monomer concentration,the monomer/cross-linker ratio,initiate content,catalyst content and temperature on the warpage rage,shrinkage rate and gelation time were analyzed.Through the experiments,optimal conditions of preparation of gel with uniform structure and little deformation rate after drying were acquired.As far as to gelcasting of PZT ceramics,the effect of chemical composition of aqueous gelcasting system on the deformation of thin large lead zirconate titanate(PZT)ceramic plates under controlled temperature and humidity were investigated.The effection of the monomer concentration,the ratio of monomer and cross-linker,initiator content on the warpage rage and gelation time were analyzed.Large area of PZT plates were manufactured with little warpage rate,and were sintered successfully.Meanwhile,the microstructure was investigated by SEM;the phase structure was determined by XRD.Piezoelectric coefficient of the samples was determined by ZJ-3A piezometer.Dielectric properties and resonant properties were determined by HP4194A impedance analyzer.The gelcasted samples and the dry pressed one with similar grain size both showed typical perovskite structures,indicated the coexistence of both rhombohedral and tetragonal phases.Gelcast samples illustrated better electrical properties than dry pressed one,which can be emerged as soft doping characteristicsDice and fill way was always brought to prepare the 1-3 piezocomposites due to its simple process.But the ceramics cracked easily because of the high hardness and fragility of the PZT ceramics.The green body with high flexural strength can be machined.Firstly the green body was diced into columns and then sintered.Secondly epoxy resin was poured into the ceramic skeleton so that the 1-3 PZT/epoxy resin composites were prepared.Thirdly the composites were polished,coated with silver and polarized.Lastly properties such as piezoelectric coefficient,dielectric properties and resonant properties of 1-3 PZT/epoxy resin composites were tested.Compared with pure PZT ceramic material,the 1-3 PZT/epoxy composites revealed lower acoustic impedance and mechanical quality factor,higher electromechanical coupling coefficient.