Abstract
In relation to the synthesis of the reinforced ceramic matrix composites, the pyrolysis mechanism of Si-C-O fiber (Nicalon NL202) in alumina powder has been studied. The pyrolytic rate has been measured with a thermobalance in an argon atmosphere at temperatures from 1773 to 1973K. The heat-treated fibers were examined with X-ray diffraction, SEM observation and tensile test. In alumina powder, the pyrolysis of the fiber was suppressed. The pyrolytic rate decreased with decreasing size of alumina powder particles, and with increasing compactness and thickness of the alumina layer. It is considered that the pyrolysis of the fiber is controlled by the growth of β-SiC crystallites and the gaseous diffusion through the interparticle pores within the powder. The high temperature strength of the fiber in alumina was appreciably retained. The equation similar to Hall-Petch's law held between the tensile strength of the fiber and the size of β-SiC crystallites.
