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Title: Nondestructive evaluation of structural ceramics by photoacoustic microscopy. Final report

Abstract

A photoacoustic microscopy (PAM) digital imaging system was developed and utilized to characterize silicon nitride material at the various stages of the ceramic fabrication process. Correlation studies revealed that photoacoustic microscopy detected failure initiating defects in substantially more specimens than microradiography and ultrasonic techniques. Photoacoustic microscopy detected 10 to 100 micron size surface and subsurface pores and inclusions, respectively, up to 80 microns below the interrogating surface in machined sintered silicon nitride. Microradiography detected 50 micron diameter fracture controlling pores and inclusions. Subsurface holes were detected up to a depth of 570 microns and 1.00 mm in sintered silicon nitride and silicon carbide, respectively. Seeded voids of 20 to 30 micron diameters at the surface and 50 microns below the interrogating surface were detected by photoacoustic microscopy and microradiography with 1 percent x-ray thickness sensitivity. Tight surface cracks of 96 micron length x 48 micron depth were detected by photoacoustic microscopy. PAM volatilized and removed material in the green state which resulted in linear shallow microcracks after sintering. This significantly limits the use of PAM as an in-process NDE technique.

Authors:
Publication Date:
Research Org.:
General Motors Corp., Indianapolis, IN (USA)
OSTI Identifier:
5251107
Report Number(s):
N-88-16868; NASA-CR-180858; NAS-1.26:180858; EDR-12815
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERAMICS; DEFECTS; PHOTOACOUSTIC SPECTROSCOPY; SILICON CARBIDES; SILICON NITRIDES; DIGITAL SYSTEMS; FRACTOGRAPHY; INCLUSIONS; PROGRESS REPORT; SENSITIVITY; VOIDS; CARBIDES; CARBON COMPOUNDS; DOCUMENT TYPES; NITRIDES; NITROGEN COMPOUNDS; PNICTIDES; SILICON COMPOUNDS; SPECTROSCOPY; 360202* - Ceramics, Cermets, & Refractories- Structure & Phase Studies

Citation Formats

Khandelwal, P K. Nondestructive evaluation of structural ceramics by photoacoustic microscopy. Final report. United States: N. p., 1987. Web.
Khandelwal, P K. Nondestructive evaluation of structural ceramics by photoacoustic microscopy. Final report. United States.
Khandelwal, P K. 1987. "Nondestructive evaluation of structural ceramics by photoacoustic microscopy. Final report". United States.
@article{osti_5251107,
title = {Nondestructive evaluation of structural ceramics by photoacoustic microscopy. Final report},
author = {Khandelwal, P K},
abstractNote = {A photoacoustic microscopy (PAM) digital imaging system was developed and utilized to characterize silicon nitride material at the various stages of the ceramic fabrication process. Correlation studies revealed that photoacoustic microscopy detected failure initiating defects in substantially more specimens than microradiography and ultrasonic techniques. Photoacoustic microscopy detected 10 to 100 micron size surface and subsurface pores and inclusions, respectively, up to 80 microns below the interrogating surface in machined sintered silicon nitride. Microradiography detected 50 micron diameter fracture controlling pores and inclusions. Subsurface holes were detected up to a depth of 570 microns and 1.00 mm in sintered silicon nitride and silicon carbide, respectively. Seeded voids of 20 to 30 micron diameters at the surface and 50 microns below the interrogating surface were detected by photoacoustic microscopy and microradiography with 1 percent x-ray thickness sensitivity. Tight surface cracks of 96 micron length x 48 micron depth were detected by photoacoustic microscopy. PAM volatilized and removed material in the green state which resulted in linear shallow microcracks after sintering. This significantly limits the use of PAM as an in-process NDE technique.},
doi = {},
url = {https://www.osti.gov/biblio/5251107}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jun 01 00:00:00 EDT 1987},
month = {Mon Jun 01 00:00:00 EDT 1987}
}

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