A PORTABLE MICROWAVE SCANNING TECHNIQUE FOR NONDESTRUCTIVE TESTING OF MULTILAYERED DIELECTRIC MATERIALS

Determining when to replace current composite ceramic materials to preserve functionality is an important cost factor in their use. The question posed is, "How to estimate performance ability of the individual composite ceramic s in situ?" Identification of damaged material is important usefulness and replacing only damaged material is an important cost factor. Recently, a portable one-sided microwave scanning technique, that can be used in situ. has been demonstrated to detect damage on actual test specimens. Work has been conducted using as-produced and intentionally impact damaged specimens. Data from the microwave scanning test method have been compared directly to through transmission x-ray examination data for the sample specimens. Each "crack" detected by through-transmission x-ray is also detected by the microwave scanning method. While the visual presentation of the microwave image is not identical to the x-ray image, it is equally unambiguous with respect to detection of features in the specimen. Based upon development work done to date. it should lie possible to achieve microwave scanning rates which would permit inspection of an area of about 4 square feet (2 feet by 2 feet) in 5 minutes or less. It appears that the method is suitable for in-situ monitoring of materials.