The tensile strength of SiC-coated carbon fibers and an application of the fibers to FRM.

Abstract

Two types of high-modulus carbon fibers were coated with various thicknesses of silicon carbide by the chemical vapor deposition method, and the tensile-test of the mono-filament was carried out. Two failure modes of fibers, i.e., a fracture followed by a cracking of a coated layer (bonding-mode), and a fracture including a debonding of a coated layer (debonding-mode), were observed by SEM, depending on the type of fiber. The tensile strength of fiber in the debonding -mode decreased with increasing thickness of a coated layer, whereas the fiber in the bonding-mode did not reduce its strength up to a certain thickness of a coated layer. And, the strength in the bonding-mode was higher than that in the debonding-mode. Aluminum matrix composites using the SiC-coated carbon fibers were produced by the squeeze casting method. The tensile strength of the composites increased with increasing thickness of the coated layer. In this case, also, the composites using the fiber in the debonding-mode were not so strong compared with that of the fiber in bonding-mode.