Location

La Jolla, CA

Start Date

1980 12:00 AM

Description

The size and material content of Fe and Si inclusions in Si3N4 have been measured by means of pulse-echo scattering of elastic waves in the frequency range 5 to 100 MHz. The inclusions were of 100 μm and 400 μm nominal diameters and were located 3 mm deep in the Si3N4. The electronic noise was reduced by signal averaging and, in some cases, the noise due to grain scattering was reduced by averaging over transducer position. The scattering amplitude A(ω) and the impulse function R(t) were obtained by a desensitized deconvolution of the reference waveform obtained by reflecting the transmitted pulse from the back surface of the sample in a defect-free region. Comparison of theory and experiment are given for A(ω) and estimates of flaw size and material content are presented.

Book Title

Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE

Chapter

15. Failure Modes, Defect Characterization, and Accept/Reject Criteria

Pages

656-662

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Long Wave Ultrasonic Characterization of Inclusions in Silicon Nitride

La Jolla, CA

The size and material content of Fe and Si inclusions in Si3N4 have been measured by means of pulse-echo scattering of elastic waves in the frequency range 5 to 100 MHz. The inclusions were of 100 μm and 400 μm nominal diameters and were located 3 mm deep in the Si3N4. The electronic noise was reduced by signal averaging and, in some cases, the noise due to grain scattering was reduced by averaging over transducer position. The scattering amplitude A(ω) and the impulse function R(t) were obtained by a desensitized deconvolution of the reference waveform obtained by reflecting the transmitted pulse from the back surface of the sample in a defect-free region. Comparison of theory and experiment are given for A(ω) and estimates of flaw size and material content are presented.