초록 ▼

Silicon carbide (SiC) fibers, or SiC bodies such as coatings, thin films, substrates or bulk objects, which have been sintered with boron containing additives to promote densification and pore removal, are further treated to remove a substantial amount of the residual boron from the SiC fibers. The

Silicon carbide (SiC) fibers, or SiC bodies such as coatings, thin films, substrates or bulk objects, which have been sintered with boron containing additives to promote densification and pore removal, are further treated to remove a substantial amount of the residual boron from the SiC fibers. The SiC fibers, subsequent to the sintering steps and either before or after cooling, are exposed to a carbon monoxide (CO) containing atmosphere at elevated temperatures from approximately 1600-2200.degree. C., but more preferably from approximately 1700-2000.degree. C., with treatment times ranging from seconds to hours to days depending on the chosen treatment temperature. The resulting SiC fibers show a significant reduction of residual boron content, a reduction of greater than 90% in some cases, while retaining high tensile strength. Fibers with less than 0.1 wt % residual boron have been obtained.

대표청구항 ▼

[ I claim:] [1.] A post-densification process for reducing the boron content of densified silicon carbide fibers, said fibers having been produced by a process chosen from the group of processes consisting of sintering, vapor-phase deposition and heat treatment of organosilicon polymers, comprising

[ I claim:] [1.] A post-densification process for reducing the boron content of densified silicon carbide fibers, said fibers having been produced by a process chosen from the group of processes consisting of sintering, vapor-phase deposition and heat treatment of organosilicon polymers, comprising the steps of providing densified silicon carbide fibers containing residual boron, said boron having been originally incorporated in the fibers as a densification aid, and subsequently, at a temperature within the range of approximately 1600 to 2200.degree. C. to promote diffusion of the boron to the surface of the fibers, exposing the densified fibers to an atmosphere consisting essentially of inert gas and up to 100 percent carbon monoxide gas in an amount sufficient to react with and remove the boron which has diffused to the surface of the densified fibers, for a period of time sufficient to reduce the amount of boron in the densified fibers.