Uniformization of Boron Nitride Coating Thickness by Continuous Chemical Vapor Deposition Process for Interphase of SiC/SiC Composites

Michiyuki SUZUKI, Yoshizumi TANAKA, Yoshiyuki INOUE, Norifumi MIYAMOTO, Mitsuhiko SATO, Koichi GODA
2003 Journal of the Ceramic Society of Japan  
SiC/SiC ¡Þ¿mEÊwm^mA± CVD @j BN¯ôÂï«úTmÏê» éعVEcgÏEäãÇKE{{TjE²¡õFEcöêÞ F»Y()F¤C7558633 Rû §Fså¬ø 19785 Þ RûåwHw@BHwÈC7558611 Rû §FsíÕä 2161 Boron Nitride (BN) coating on sintered SiC bers (Tyranno SA) by a continuous chemical vapor deposition (CVD) process was developed with the ultimate goal of controlling the interface in SiC/SiC composites. BN coating by a continuous CVD process was conducted at 1580 C under a pressure of approximately 1.3~10 2 Pa. Reactant gases were NH 3 and BCl 3 , both
more » ... and BCl 3 , both diluted by Ar; the yarn speed was 4.5 mm/s. Conventional ex periments revealed that the BN coating thickness across the tow varied signicantly. Hence, the CVD process was modied not only by adjusting the amounts of reactant gases, but also by reducing the yarn ten sion and setting a new furnace for removing the sizing agent of the ber tow. The BN coating thickness ob tained by the modied process was signicantly more uniform than that achieved by a conventional process. The BN coating had a layered structure; it was nearly stoichiometric and pure, with little O or C. The BN coated SA ber retained 90÷ of the strength of the asreceived SA ber. Moreover, a minicomposite rein forced with a BNcoated SA ber of 1600 laments (ber volume fraction: 10.8÷) was fabricated by a poly mer inltration and pyrolysis (PIP) method. This minicomposite exhibited a higher fracture strength (199 MPa) at room temperature and a higher retention ratio (82÷) of the fracture strength at 1400 C in air as compared to a minicomposite obtained by a conventional process (173 MPa and 73÷).
doi:10.2109/jcersj.111.865 fatcat:v3ovwhhwyfgabc35nzpsele7sq