Tensile fracture behavior and strength distribution of SiCf/SiC composites with different SiBN interface thicknesses

Abstract

The borosilicate nitride (SiBN) interface was firstly fabricated in SiC fibers reinforced SiC matrix (SiCf/SiC) composites by low-pressure chemical vapor infiltration (LPCVI). Tensile fracture behavior and strength distribution of SiCf/SiC composites with different SiBN thicknesses were investigated. The results showed that the tensile strength first increased and then declined with increasing interface thickness. The maximum value of tensile strength was 550.8MPa with a 1000nm SiBN interface. Non-brittle tensile fracture behavior of SiCf/SiC composites with a SiBN interface was demonstrated. The pull-out length and amount of fibers had a similar variation trend with increasing interface thickness. Strength distributions of SiCf/SiC composites with different interface thicknesses followed Weibull distribution with two parameters. Weibull modules of tensile strength increased first, and then decreased with increasing interface thickness. The maximum value of the Weibull module was 11.0224 when the interface thickness was 1000nm, which indicated the highest reliability of SiCf/SiC composites. The mean value of tensile strength for SiCf/SiC composite with 1000nm interface was 576.82MPa obtained by the theory calculation, which was consistent with the result of experiment (550.8MPa) very well.