Experimental evaluation of clad metallic buffer rods for high temperature ultrasonic measurements

The fabrication, evaluation and several applications of metallic buffer rods consisting of a core and a cladding are presented. The clad rods can have a taper shape and the cladding is fabricated by thermal spray techniques. Clad rods as long as 1 m have been fabricated. Experimental results show that the ultrasonic signals detected at 5 MHz with these buffer rods have very high signal to noise ratio (>35 dB) for both longitudinal and shear waves in a reflection mode. Applications to the measurement of the thickness of hot plates and molten metals up to 960°C and to the on-line monitoring of polymer extrusion are reported.

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