Effects of interlayers on interfacial shear strength and flexural properties of Tyranno-SA fiber-reinforced CVI-SiC/SiC composites

摘要

Several SiC/SiC composites reinforced with a highly crystalline β-SiC fiber, Tyranno-SA, were fabricated using the chemical vapor infiltration (CVI) process. The flexural properties and fracture behaviors were investigated using three-point bending tests. Various pyrolytic carbon (PyC) or multi-interlayers were deposited in the composites using an isothermal CVI process to modify the interfacial bonding and fiber sliding resistance. The bending test results revealed a close PyC layer dependence of the flexural strength. The ultimate strength showed quick increase with the increasing of the PyC layer thickness up to ～100nm, beyond which slight increase of the ultimate strength via the PyC layer thickness till ～200nm was noticed. The interfacial shear strengths (ISS) of these composites were extracted with single fiber pushout tests, which revealed very large 155 from ～195MPa to over 633MPa depending on the thickness of the PyC layer.