RESISTANCE OF Si_3N_4/C_f CERAMIC-MATRIX COMPOSITES TO HIGH-TEMPERATURE OXIDATION

摘要

In fiber-reinforced ceramic-matrix composites (CMC), short-term, rapid oxidation at 1500 deg C is shown to promote the formation of silicon dioxide. This results in the buildup of a compact film with a high degree of crystallinity; the ensuing effects are closure of pores, self-healing of microcracks, and loss of mass reduced to a minimum. The carbon fibers retain structural integrity in all CMC. This technique can be employed to protect CMC-based components and thus to extend their service life.