Interfacial Bonding and Friction in Silicon Carbide [Filament]‐Reinforced Ceramic‐ and Glass‐Matrix Composites

Interfacial shear strength and interfacial sliding friction stress were assessed in unidirectional SiC‐filament‐reinforced reaction‐bonded silicon nitride (RBSN) and borosilicate glass composites and 0/90 cross‐ply reinforced borosilicate glass composite using a fiber pushout test technique. The interface debonding load and the maximum sliding friction load were measured for varying lengths of the embedded fibers by continuously monitoring the load during debonding and pushout of single fibers in finite‐thickness specimens. The dependences of the debonding load and the maximum sliding friction load on the initial embedded lengths of the fibers were in agreement with nonlinear shear‐lag models. An iterative regression procedure was used to evaluate the interfacial properties, shear debond strength (T d ), and sliding friction stress (T f ), from the embedded fiber length dependences of the debonding load and the maximum frictional sliding load, respectively. The shear‐lag model and the analysis of sliding friction permit explicity evaluation of a coefficient of sliding friction (μ) and a residual compressive stress on the interface (σ 0 ). The cross‐ply composite showed a significantly higher coefficient of interfacial friction as compared to the unidirectional composites.