Ultrasonic detection of voids in ceramic composites

Conference · Thu Dec 31 23:00:00 EST 1987

OSTI ID:6775411

Walter, J B; Lott, L A

The particular material under study consists of a Nicalon fiber weave reinforcing fabric in a silicon carbide matrix formed by a chemical infiltration process. The process can result in high porosity and voids because of incomplete infiltration by the SiC-containing vapor. The basic objective of this NDE study is detection and characterization of the porosity and voids. Previous work established correlations between ultrasonic attenuation and velocity and material porosity. The material was found to be highly attenuating, particularly at high frequencies, which limits useful measurements to those made by through-transmission techniques at frequencies of /approximately/5 MHz or less, depending on sample thickness and porosity. Thermoelastic generation of ultrasound by a pulsed laser beam was found to have advantages over insonification by conventional piezoelectric transducers because of more direct coupling of ultrasound into the material and because of the higher energy available with the laser. The ability of ultrasonics to image variations in the distribution of porosity in samples was also demonstrated. 3 refs., 4 figs.

• Research Organization: EG and G Idaho, Inc., Idaho Falls (USA)
• DOE Contract Number: AC07-76ID01570
• OSTI ID: 6775411
• Report Number(s): EGG-M-88135; CONF-880760-4; ON: DE88016952
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
42 ENGINEERING
420500 -- Engineering-- Materials Testing
ACOUSTIC TESTING
CARBIDES
CARBON COMPOUNDS
CERAMICS
LASERS
MATERIALS TESTING
NONDESTRUCTIVE TESTING
POROSITY
PULSE TECHNIQUES
SILICON CARBIDES
SILICON COMPOUNDS
SOUND WAVES
TESTING
ULTRASONIC TESTING
ULTRASONIC WAVES
USES
VOIDS