Research On Preparation And Properties Of Piezoelectric Composites For Health Monitoring

With the development of traffic construction in China,more and more attention had been paid to the health conditions of the roads,which puts forward some requirements for sensor health monitoring.Whereas,the existing sensors have the defects of large volume,high modulus and poor compatibility,which has become bottleneck problems of health monitoring.Piezoelectric materials have the advantages of sensitive reaction and large output signal,the sensors,made by this materials as pressure sensitive elements,have the fast response speed,low cost,simple structure and the ability of adapting the environment,are widely used as health monitoring systems.Based on the above,this paper mainly study the properties of 0-3piezoelectric composites with carbon black,and the main content was shown as follows:Pressing and forming method was used to make the 0-3 asphalt-based piezoelectric composites and 0-3 emulsified asphalt/cement-based piezoelectric composites with piezoelectric ceramics as piezoelectric phase,asphalt and emulsified asphalt/cement as matrix phase,carbon black as conductive phase.Experiments were proceeded to study the effect of molding process on the properties of 0-3 piezoelectric composites,and the best molding process was determined.The molding pressure and time of asphalt-based piezoelectric composites was 80MPa and 3min,the same condition of emulsified asphalt/cement-based piezoelectric composites was 100MPa and 20min.Orthogonal test was conduct to determine the mixture ratio of emulsified asphalt/cement piezoelectric composites.The materials ratio was determined as 75%of piezoelectric ceramics volume fraction,0.32 of water cement ratio,0.31 of emulsified asphalt/cement quality ratio.Experiments were conducted to analyze the effect of curing time on the properties of0-3 emulsified asphalt/cement-based piezoelectric composites,and the curing time was determined as 7d.the best poling conditions were determined according to the experiments conducted to analyze the effect of poling conditions on the piezoelectric materials,The polarization electric field intensity,polarization temperature and polarization time of asphalt-based composites was 2kV/mm,40?,5min.the same condition of emulsified asphalt/cement-based composites was 3kV/mm,80?,20min.The aging time of three different polarization conditions had effect on the properties ofcomposites.The d₃₃ values of asphalt-based materials decreased with increasing aging time,the last test result increased.The d₃₃ values of emulsified asphalt/cement composites had a more complex trend,the peak value of d₃₃ increased and appearing the repeat change.With extending aging time,the maximum and minimum of d₃₃ values decreased.The performance parameter of asphalt-based composites with different content of PZT and carbon black was conducted.The results shown the optimal volume fraction of PZT as80%.When carbon black had a volume fraction of 0.3%,piezoelectric strain factor,dielectric constant,planar electromechanical coupling coefficient had the maximums of 75.74pC/N,154.89,37.73%,and dielectric loss had the minimum of 0.38.The performance parameter of emulsified asphalt/cement-based composites with different content of PZT and carbon black was conducted.The results showed the optical volume fraction of PZT as 72.5%.When carbon black had a volume fraction of 0.2%,piezoelectric strain factor,dielectric constant,planar electromechanical coupling coefficient had the maximums of 45.7pC/N,135.712,19.41%,The dielectric loss is 0.0019.