Shell thickness measurements in composite conductors using ultrasonics

Ultrasonics may be well suited for defect detection and shell thickness measurements in certain composite electrical conductor wires. The composite which is amenable to nondestructive evaluation (NDE) by ultrasonics and investigated here, is a monofilamentary thin wall composite rod used as the precursor for cryogenic wire (cryoconductor) applications. The composite is comprised of a 99.999 percent pure aluminum core which is protected by an Al-4Fe-2Ce alloy shell. The shell adds needed strength to the cryoconductor since aluminum of very high purity exhibits high ductility and low yield strength (DeFrese and Hartwig, 1991). During manufacture, the cryoconductor is heavily deformed as it is drawn or extruded to long lengths. This processing provides for a sound metallurgical bond between the core and shell (Premkumar, et al, 1990). Ultrasonic techniques are shown to be quite effective in determining the shell thickness despite the good core-shell bond and the similar acoustic characteristics of the core and shell materials.

Shell thickness measurements in composite conductors using ultrasonics Conference Paper