Nondestructive Evaluation of the Thermal Cycling Effects on Graphite/Aluminum Precursor Wire

The objective of the work was to nondestructively examine the effects of thermal cycling on properties (e.g., torsional velocity and electrical resistance) of graphite/aluminum (Gr/A1) precursor wire. Precursor wires were periodically heated at selected temperatures for various periods of time; the exact heating period being dependent on the test temperature. Wires were tested in the as-received condition and after each thermal excursion. Changes occurred in both the torsional velocity and the resistance; although at different rates and to different extents. Subsequent longitudinal velocity tests run on the heat treated sections of the wires showed little if any changes in the longitudinal velocities.