A comparative study of tensile strength of Cf/SiC composites having single layer and multilayer interphases

Abstract

Tensile behaviour of stitched 2D carbon fiber reinforced silicon carbide (Cf/SiC) composites having variable interphases was studied in detail. Two types of interphases (single layer of pyrocarbon interphase and multilayers of pyrocarbon/silicon carbide) were deposited initially on the carbon fiber preforms followed by silicon carbide matrix infiltration. Multilayer interphase was deposited for two different durations. Cf/SiC composites were prepared by isothermal chemical vapour infiltration (ICVI) technique. The as-cut and silicon carbide seal coated samples were subjected to tensile tests in air at room temperature and at 1200 °C. The effect of seal coating and type of interphase on the tensile properties was studied. It was observed that the composites (in uncoated and seal coated condition) with multilayer interphase showed higher values of tensile strength at both the test temperatures as compared to single layer interphase. Also, the composites fabricated with multilayer interphase deposition for longer duration showed highest values of tensile strength at both the test temperatures. The fractured regions of tensile tested samples were analyzed in detail by SEM in order to understand microstructure-property relationships.