Determination of Interfacial Properties Using a Single‐Fiber Microcomposite Test

A single‐filament microcomposite consisting of 143‐μm‐diameter CVD SiC, a thin “interfacial” coating, and a thick (130–160 μm) CVD SiC matrix sheath was tested in tension to determine the interfacial shear properties of carbon and BN interfacial coatings. Load/displacement and acoustic emission were used to determine the mechanical behavior of the microcomposites and matrix cracking. Optical and electron microscopy were performed to confirm the extent and nature of matrix cracking and to analyze the micro‐composite microstructure. The interfacial properties were determined from matrix cracking and load/displacement hysteresis techniques. Direct measurement of the interfacial sliding stress from push‐out and pull‐out experiments were in good agreement with two of the three microcomposite systems studied.