Variation of mechanical properties by carbon fiber volume percent of carbon fiber reinforced reaction bonded SiC

Abstract

The composite added with surface-coated chopped carbon fiber showed the microstructure of a 3 dimensional discretional arrangements. The fiber reinforced reaction bonded silicon carbide composite, containing the 50 vol% carbon fiber, showed the porosity of < 1 vol%, 3-point bending strength value of 250MPa and fracture toughness of 4.5MPa m 1/2. As the content of carbon fiber was increased from 0 vol% to 50 vol% in the composite, fracture strength was decreased due to the increase of carbon fiber, which has a less strength than SiC and molten Si. On the other hand, the fracture toughness was increased with increasing the amount of carbon fiber. According to the polished microstructure, carbon fiber was shown to have a random 3 dimensional arrangement. Moreover, the fiber pull-out phenomenon was observed with the fractured surface, which can explain the increased fracture toughness of the composite containing high content of carbon fiber.