Microstructures of a SiC-ZrC Ceramic Fiber Derived from a Polymeric Precursor

Continuous ceramic fiber comprising silicon carbide-zirconium carbide (SiC-ZrC) binary phases was obtained through melt spinning, electron-beam curing and pyrolysis of a pre-ceramic precursor of polyzirconocenecarbosilanes (PZCS). After pyrolysis and heat treatment, ZrC particles with mean diameters of 15-20 nm were formed and homogeneously dispersed in a matrix of fine crystalline beta-SiC with an average grain size of 6-10 nm. Concentration of Zr in the fiber varies from 14.88% to 17.45% by mass. Fibers consisting of near-stoichiometric ZrC and SiC with little free carbon can be obtained through pyrolysis decarbonization of the as-cured fiber in hydrogen from room temperature to 1000 degrees C, and subsequently heat treatment in argon up to 1600 degrees C for 1 h. High-temperature treatment of these amorphous inorganic fibers leads to crystallization of the binary phases of beta-SiC and ZrC. The removal of free carbon under hydrogen results in more rapid growth of beta-SiC and ZrC crystals, in which obvious aggregation of the dispersed ZrC particles among the continuous beta-SiC matrix can be ascribed to a fast migration of Zr cation.