Mechanical behavior and failure mechanisms of boron carbide based three-layered laminates with weak interfaces

The effect of weak interfaces on failure mechanisms of a three-layered composite was studied. Three-layered B4C/B4C–Cnanofibers laminates have been produced using a hot pressing technique. The laminates were designed with thick (∼2.6 mm) outer layers of B4C and a thin (∼90 μm) center layer of B4C–70 wt.% Cnanofibers. Based on the difference in coefficients of thermal expansion and Youngʹs moduli of the pure B4C and B4C–70 wt.% Cnanofibers layers, it was estimated that low tensile thermal residual stress with a magnitude of 11.3 ± 2.5 MPa was developed in the thick B4C outer layers, and compressive residual stress with a magnitude of 455.7 ± 5 MPa was developed in the thin central B4C–70 wt.% Cnanofibers layer. The apparent fracture toughness of laminates was measured and based on the estimated fracture toughness values, a threshold stress was calculated.