Abstract
To improve the thermal and mechanical stability of SiCf/SiC or C/SiC composites with SiBN interphase, SiBN coating was deposited by low pressure chemical vapor deposition (LPCVD) using SiCl4-BCl3-NH3-H2-Ar gas system. The effect of the SiCl4 flow rate on deposition kinetics was investigated. Results show that deposition rate increases at first and then decreases with the increase of the SiCl4 flow rate. The surface of the coating is a uniform cauliflower-like structure at the SiCl4 flow rate of 10 mL/min and 20 mL/min. The surface is covered with small spherical particles when the flow rate is 30 mL/min. The coatings deposited at various SiCl4 flow rates are all X-ray amorphous and contain Si, B, N, and O elements. The main bonding states are B-N, Si-N, and N-O. B element and B-N bonding decrease with the increase of SiCl4 flow rate, while Si element and Si-N bonding increase. The main deposition mechanism refers to two parallel reactions of BCl3+NH3 and SiCl4+NH3. The deposition process is mainly controlled by the reaction of BCl3+NH3.
Highlights
Continuous fiber reinforced silicon carbide ceramic matrix composite (CFCC-SiC) are considered as one of the most promising new generation of thermo-structural materials, which exhibit excellent properties in many aspects, such as high temperature resistance, low density, high specific strength, high specific modulus, antioxidant ablation, and high reliability [1,2]
The oxidation resistance of BN interphase is still poor when SiCf /SiC or Cf /SiC composites are used at relatively higher temperatures and in an oxidizing environment
The results indicate that deposition rate varies greatly with the increase of SiCl4 flow rate
Summary
Continuous fiber reinforced silicon carbide ceramic matrix composite (CFCC-SiC) are considered as one of the most promising new generation of thermo-structural materials, which exhibit excellent properties in many aspects, such as high temperature resistance, low density, high specific strength, high specific modulus, antioxidant ablation, and high reliability [1,2]. The oxidation resistance of BN interphase is still poor when SiCf /SiC or Cf /SiC composites are used at relatively higher temperatures and in an oxidizing environment. It is necessary to improve the oxidation resistance of the BN interphase in SiCf /BN/SiC and Cf /SiC composite. In recent study of SiCf /BN/SiC composite, BN coating will be oxidized and gasified in 1–10% PH2O environment at 700–800 ◦ C, even though the h-BN was deposited at 1800 ◦ C. The BN interphase containing 22 wt % Si element deposited at 1400 ◦ C survived after work for 1000 h in the same environment [7]. Doping BN interphase with Si will be an effective way to improve the antioxidant ability of the BN interphase in SiCf /BN/SiC composites or Cf /BN/SiC composites
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
