Cure monitoring apparatus having high temperature ultrasonic transducers

摘要

An apparatus for monitoring the curing of a fiber reinforced composite plastic which is cured at temperatures of the order of 350 DEG C. and an ultrasonic transducer assembly useful in the apparatus. The transducer assembly comprises a lithium niobate piezoelectric element having anisotropic coefficients of thermal expansion which is mounted on a metal base of the transducer assembly by means of a layer of structured copper. The structured copper is thermo-compression diffusion bonded to the lithium niobate element and to the metal base, and is compliant in a transverse direction to compensate for differential thermal expansions while affording good electrical and thermal conductivity and good acoustic coupling between the lithium niobate element and metal base.