Measurements of the Material Properties of a Laminated Piezoelectric Stack at Cryogenic Temperatures

Future NASA missions require cooling of large structures in space. One class of thermal management solutions for providing controlled, distributed cooling would utilize actively controlled micro-scale valves that are integrated with heat exchangers and sensors in order to provide independent, local temperature control. The most attractive actuation method for these micro-valves is a multilayer piezoelectric (PZT) stack because this technology is capable of providing large force using reasonable voltages (e.g., < 100 V) with minimal power draw. In order to design a micro-valve configuration that takes advantage of this actuation technique, it is necessary to obtain information regarding the behavior of piezoelectric materials at cryogenic temperatures. This paper describes a test facility that was designed to achieve precise measurements of the coefficient of thermal expansion (CTE) and PZT stack actuator constant ( 33 d ) from 40 K to room temperature. The operation of the facility is validated by measuring the CTE of a copper alloy with wellknown behavior. Experimental measurements are subsequently presented for a commercially available PZT stack.