Materials evaluation using long clad buffer rods

Materials characterizations using long clad buffer rods with high spatial resolution and at high temperature are presented. The buffer rods consist of a fine grain steel core and thermal sprayed stainless steel cladding, and the lengths are up to 1 m. The signal to noise ratio (SNR) of the reflected signal at the end of buffer rods is better than 40 dB at 5 MHz. The thickness measurement for molten aluminum is demonstrated under industrial environment. In order to perform materials evaluation with a high spatial resolution, a spherical acoustic lens has been fabricated at the end of the rod and its focusing ability is investigated.