Fabrication of Simple and Ring-Type Piezo Actuators and Their Characterization

A piezo multilayered stack of height 10？mm is fabricated using 80？μm thick PZT tapes prepared by tape-casting technique. About 120 layers of thin tapes are dried, screen-printed with Pt-electrode paste, stacked, laminated, and then isopressed to obtain a green multilayered stack. Cofiring of the stack is carried out at C for 1？h with very slow heating rate ( per 1？h). The sintered stack is poled at 2？kV per mm in hot ( C) silicone oil bath for 45 minutes, and free displacement and block force were characterized. The actuator generates free displacement of 10？μm (0.1% strain) and block force of 1427？N at 175？V. In a similar way, a ring-shaped multilayered PZT stack was fabricated; the displacement was measured to be 8？μm. The ring-type actuator is mainly used for fluid flow control in space vehicles. 1. Introduction Piezo actuators/sensors are mainly used for smart applications because of their (i) fast response time, (ii) high frequency response, (iii) precession control, (iv) capablity of generating high block force, and so forth [1]. The sensors and actuators with appropriate control unit together form a smart system. Piezo sensors and actuators are used for various applications such as vibration control of aerospace structures, development of smart aeroplane wings, propellant flow control in space vehicles, and fuel flow control in automobile engines. Lead zirconate titanate (PZT) is a well-known piezo material that produces electric charges on application of mechanical stress (as sensor) or undergoes dimensional change when subjected to an electric field (as actuator) [2–6]. For these properties PZT is frequently used for fabrication of multilayered actuators. Ring-type actuator is a special type of actuators exclusively used for flow control purpose. Weight/size reduction of a space instrument or subsystem of a space craft is necessary to save enormous launching cost as well as to increase the mission duration. The reduction in thrust levels for miniaturized spacecraft requires very fine propellant flow rates. Solenoid valves used for flow control are very heavy. Piezo-material-based microactuators could be best suitable for these applications due to their precision flow control [7] effected by the gradual application of voltage and also due to their low weight. Therefore, in this study, an effort has been made to fabricate PZT multilayered stack and a ring-type actuator by tape casting technique and block force and displacement were characterized. 2. Experimental Procedure 2.1. Fabrication of Simple Multilayered (ML) Stack PZT stacks were