The effect of deposition temperature of BN interphase on the tensile properties of SiC fibers

Abstract

The chemical vapor infiltration (CVI) process was utilized to deposit controllable BN interphase on SiC fibers by using BCl3–NH3–H2 as precursors at low pressure from 900 °C to 1200 °C. Various characterization methods, such as SEM, Raman, XRD, XPS and TEM, are used to detect the microstructure and elemental composition of the interphases. The effects of deposition temperature on the morphology, deposition kinetics, elemental composition, and tensile properties of BN interphase coated fibers were investigated. The results indicated that the BN interphases deposited at the temperature from 900 °C to 1200 °C were compact and uniform. The growth rate increases first and then decreases with the increase of deposition temperature. The reaction rate reaches the maximum value at 1100 °C. High temperature deposition can improve the crystallinity of the BN interphase. Regardless of the deposition temperature, the tensile strength of the fiber decreases due to the increasing diameter after depositing the BN interphase. The deposition temperature had a significant impact on the tensile strength of fibers, especially at 1200 °C.