ZnO surface modified PZT for enhanced ceramic composite thick film sensors

Acoustic emission (AE) sensors are capable of detecting elastic waves emitted when cracks advance in engineering structures. To provide real time continuous monitoring, such sensors would have to remain permanently in place, but this is uneconomic and impractical to realise in many situations. The availability of low cost and small AE sensors is hampered by the poor piezoelectric properties of materials that can easily be processed and the processing challenges associated with materials that exhibit high piezoelectric properties. Here, a ZnO surface treatment for lead zirconate titanate (PZT) ceramic particles is presented that enhances the interfacial bonding between PZT and polymer to allow mechanically robust composite films to be created that exhibit d₃₃ piezoelectric coefficient of 15 pC/N after corona poling at 100°C. Films of modified PZT–polymer material have been used to detect simulated acoustic emission events. A comparison between such devices and commercially available PZT ceramic based devices is drawn.