Preparation And Properties Of NiTi SMA/PZT Composite Based On The PZT

Lead zirconate titanate (PZT) piezoelectric ceramic has very stable piezoelectric effect, high electromechanical coupling coefficient and good mechanical quality factor when it is used as sensor or driver. But its poor mechanical property restricts the application. For exerting the predominance of the PZT and improving its mechanical property sufficiently, we try to prepare a new composite material with NiTi SMA film and PZT. It may be one of new continuation for the PZT application.In this paper, the NiTi SMA film was directly deposited on the PZT substrate by magnetron sputtering. After crystallization treating, the NiTi SMA/PZT composite material was obtained. The effects of substrate pre-heating temperature, Ar gas pressure, sputtering power and the surface state of the substrate on the surface morphology of the NiTi SMA film, the combination of the composite material between the NiTi film and PZT substrate and the deposition rate were studied with the SEM. The diffusion of the elements was analyzed by the EDS. The effects of different heating mode, heating temperature and holding time on the phase of the NiTi SMA film were studied with the XRD. Then the suitable preparation technology was determined. The compression performance was test by the miro-hardness instrument to investigate the combination of the NiTi film between PZT substrate. The bend strength was tested with three-point bending to study the effect of NiTi SMA film on the PZT substrate. The piezoelectric constant d33, the electromechanical couple coefficient Kp and dielectric loss tgδwere tested by ZJ-3A type static apparatus, Automatic LCR Meter4225 for checking the effect of the NiTi SMA film on the piezoelectricity of the PZT substrate.The results showed that the suitable parameter as follow: The substrate must be strict cleaned. The pre-heating temperature of substrate was 150℃. The Ar gas pressure was 0.7Pa. The sputtering power was 150W. In this condition, the cavities and gaps on the NiTi SMA film surface were few. The combination of the NiTi SMA/PZT composite material between the NiTi SMA film and PZT substrate was well. The deposition rate was suitable. The element diffusion range between the substrate and the NiTi SMA film crystallized by two steps method was small. With the suitable crystallization technology of 600℃of heating temperature and 30min of holding time, the surface morphology of the NiTi SMA/PZT composite material was dense, uniform and with little defection and the combination mode between the NiTi SMA film and PZT base was tight combination.The testing results of the mechanical property showed that: The bigger pressure was 100gf. The binding force between the NiTi SMA film and PZT substrate was about 0.49N. The bend strength of the NiTi SMA/PZT composite material was improved about 22.9% than the PZT. The values of d33 and Kp are higher and the value of tgδis lower compared with the PZT. Well combination and restraint stress between the NiTi SMA film and the PZT substrate are good for the movement of the electric dipole and ensured the PZT displaying the piezoelectricity sufficiently.