Characterization of fiber/matrix interfaces in composites with a boron nitride matrix

The fracture behavior of boron nitride (BN) composites reinforced with several types of carbon and ceramic fibers has been examined. Fiber properties and fiber/matrix interface characteristics were found to control the mechanical strength and toughness of the composites. Transmission electron microscopy demonstrated preferential orientation of the BN matrix parallel to the fiber surfaces. Auger electron spectroscopy was then used to examine the fiber/matrix interface and locate the path of interface debonding. Single-fiber-push-out experiments were used to quantify the mechanical properties of the fiber/matrix interface. The bulk composite fracture properties were consistent with current understanding in that a lower interfacial toughness was found to enhance fiber pull-out and increase the composite toughness. Matrix abrasion during fiber sliding had a significant effect on the sliding behavior of the fibers. (C) 1996 Published by Elsevier Science Limited