Study On Preparation And Properties Of Piezoeleetrie-damping/Epoxy Composites

The piezoelectric ceramic/polymer composite has both a piezoelectric ceramic and a polymer merits. This composite is the new type functional material. Epoxy resin has a great of virtues, such as large rigidity, good corrosion resistance, good flame retardancy and excellent insulating property. With combining piezoelectric ceramic,carbon and epoxy resin, the dielectric and damping properties of epoxy resin will be improved because of high dielectric and piezoelectric properties of piezoelectric ceramic and conductive property of carbon. So epoxy resin will be expanded the application in the field of the intelligent material.The P82/CB/EP composites of epoxy resin (EP), lead zirconate-titanate ceramics(P82) and conductive carbon (CB) are prepared by casting and twice-castingmethods. With changing the material composition, the effects of composition on thestructure, conductive property, dielectric property and damping property are studied indetails. The piezoelectric effect on the damping property is also investgated.The SEM show that,the P82/CB/EP composite with a smaller quantity of P82 and CB has compact and well-proportioned structure and caking capacity at interface instead of the one with larger content of P82 and CB, which agglomerate and shape void in some degree.The results of the conductive property show that the resistivity of P82/CB/EP composite decreases rapidly with increasing the conductive material content. And the resistivity of P82/CB/EP composite also decreases with increasing the frequency.The results of the dielectric property show that the dielectric property of composite is better than epoxy resin, based on the dielectric property of P82. With increasing the P82 content the dielectric constant of P82/CB/EP composites increases. With the PMN content increases from 10% to 50%, the dielectric constant increases from 5.6 to 33.3 and the dielectric loss also increases. And with the P82 content of 20%, the dielectric constant and the dielectric loss of P82/EP composites show a non-linear increase with CB content increasing. From the relation between dielectric constant and frequency, it is obtained that in the frequency range between 10⁶ to 5×10⁶Hz, the dielectric constant of P82/CB/EP composites decreases with the frequency increasing. At the high frequency, P82/CB/EP composites dielectric constants are more stable. The more PMN content is or the conductive material content is near the percolation value, the more rapidly decrease of dielectric constant with the frequency increasing is.The results of the damping property show that, in the same load and frequency, the damping property has the nonlinear change. With the P82 content increasing, the damping property is the best when P82 content is 20%. And with the increasing of the load or the frequency, the tanδ_max and TA increase, the damping property improve.The P82/CB/EP composites, which is processed by twice-casting methods with similar sandwich structure, has advanced damping property. Under the same P82 and CB content, the damping property is much batter than the one processed by casting methods. With the P82 content increasing, the damping property is the best when P82 content is 10%. And simultaneously the tanδ_max is 1.182, theΔT is 44.2℃and the TA is 32.17.