Abstract
It is well-known that dense SiC matrix composites reinforced by SiC fibers with BN coating can be fabricated by subsequent reaction sintering with molten Si. In this experiments, it was confirmed that the mechanical properties of continuous Si-C fibers (Hi-Nicalon) were not affected by the thickness of the BN coating using CVD process and the bending strength of reaction-sintered SiC increased from 500 to 1000MPa with decreasing the size of residual silicon. The effect of SiC matrix strength on the matrix cracking stress in unidirectional fiber-reinforced SiCf/SiC composites was investigated by use of these data. As a result, it made clear that the matrix cracking strength in SiCf/SiC composites increased with increasing the SiC matrix strength. There are the upper limits of the SiC matrix strength deduced from the SiC fiber strength and the fiber volume fraction to achieve the apparent ductile fracture of the SiCf/SiC composites.
