2000 年 49 巻 9 号 p. 1017-1022
A sintered SiC fiber-bonded ceramic was synthesized by hot-pressing the plied sheets of an amorphous Si-Al-C-O fiber. Here we describe the microscopic structure and mechanical properties of the two-directional sintered SiC fiber-bonded ceramic synthesized from three kinds of starting fiber with different concentration of excess carbon and oxygen and different fiber diameter. The desirable sintered SiC fiber-bonded ceramic has been found to show a perfectly close-packed structure of the hexagonal columnar fibers with a very thin interfacial carbon layer. Furthermore, the interior of the fiber element was composed of sintered β-SiC crystal without an obvious second phase at the grain boundary and its triple points. Its mechanical properties at high temperatures are closely relate to the microscopic structure. The strength and the fracture behavior are strongly dominated by the uniformity of the interfacial carbon layer and a densified structure of the fiber element. A reduction in the excess carbon and oxygen included in the starting fiber resulted in the improved mechanical strength of the fiber-bonded-ceramic. Furthermore, it was found the highest four-point bending strength (-500MPa) could be obtained by the use of a thinner starting fiber (8μm) with low concentration of carbon and oxygen. It was concluded from these facts that the improvement in mechanical strength was strongly related to the formation of the uniform interfacial carbon layer and the most densified structure of the fiber element.