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FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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- 307 -<br />

NDE OF STRUCTURAL CERAMICS BY HIGH FREQUENCY ULTRAS<strong>ON</strong>ICS<br />

A. fakn.<br />

National Re.izan.ck. Council o I Canada<br />

ABSTRACT<br />

A high frequency ultrasonic system with computer controlled data acquisition and<br />

analysis has been described. The system has been used to detect surface flaws in<br />

the size range of 20-300 um in hot pressed silicon nitride. The detection<br />

technique is based on Rayleigh waves which are generated as a result of the mode<br />

conversion of compressional waves incident from water onto the surface of the<br />

test material at near the Rayleigh angle. The scattering of the Rayleigh waves<br />

by surface cracks has been detected, analysed in the time and frequency domains,<br />

and correlated with the size of the cracks.<br />

This work was supported by the Defence Research Establishment, Pacific,<br />

Victoria, B.C. and was carried out at the Ontario Research Foundation,<br />

Mississauga, Ontario.

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