| Piezoelectric ceramic is a kind of functional ceramic used for the transform between mechanical energy and electric energy. As one of the initial piezoelectric ceramics known and used by people, PZT piezoelectric ceramic has excellent comprehensive piezoelectric properties. Its structure of perovskite lays a foundation of modifying by doping other elements, as well as to prepare PZT-based polynary system piezoelectric ceramics. PMS-PZT is a kind of ternary system piezoelectric ceramics with a performance included a high electromechanical coupling factor(the max can be 5300), a low dieletric loss and a good temperature stability, which is fit for using under high-frequency and high-power conditions. As the other ceramic materials, the bodies of PMS-PZT ceramic have the characteristics of high hardness and low fabrication toughness etc. These bring a problem in subsequent machining. Therefore, how to guarantee a high yield, a low cost and a good performance at the same time becomes a focus in people’s research when preparing PMS-PZT ceramics with an irregular shape.Gel-casting is a near net forming process which can solidify the ceramic suspension with a high solid loading and a low viscosity in situ. When preparing ceramic parts of complex shape, it has advantages, such as easy operation, low cost and making degreasing and sintering in the same procedure because of the low content of organics. PMS-PZT ceramics were prepared by this method in this research, we mainly studied the preparation techniques in preparing PMS-PZT piezoelectric ceramics with a AM-MBAM gel system, as well as the properties.The pH value of the suspension fit for casting was 10, which was investigated through the viscosity test and sedimentation test. When pH=10, the content of TH-908 and TAC respectively reached 0.34wt% and 1wt% as the viscosity of a 50vol.% solid loading decreasing to the minimum 145mPa·s and 570mPa·s; APS was used as initiator while TEMED was used as catalyst and influence of their content on idle time before the gelation was investigated by testing the temperature change of the suspension. When the content of initiator and catalyst were 0.2vol.%-0.4vol.% and 0.2vol%-0.3vol.%, the range of the idle time was 8min-15min; The uniformity of gel bodies was investigated by testing the bending strength of a green body. Cross-linking agent has a strong effect on the uniformity of the green bodies. When the concentration of monomer in premixed liquid was 16wt%, the content rate of monomer and cross-linking from 16:1 to 32:1 made the bodies have a good uniformity; The heating temperature curve of degreasing were determined by studying oxygenolysis of the organics caused by temperature change through the DSC-TG testing. In the test, the organics in a green body intensively decomposed at 384.28℃ and 490.51℃ and finished decomposing at about 520℃; Through the SEM, XRD and Archimedes method, we know gel-casting method could make the sintered bodies have a uniform microstructure. The structure of sintered bodies was tetragonal perocskite structure after sintering at 1150 ℃,1200℃ and 1250℃; The sintered body at 1200 ℃ had better compactness and piezoelectric properties than the samples sintered at 1150℃ and 1250℃. Besides the sintered body with a solid loading of 56vol.% at 1200℃ got the density of 7.6120g/cm3, reaching 95% of the theoretical density.In the experiment, PMS-PZT piezoelectric ceramic meeting requirements was obtained by gel-casting method. We believe gel-casting method will fulfill its commercial process on a large scale in the near future because of its advantages in preparing ceramics with irregular shapes and the low cost. |
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