**4. Conclusions**

We investigated the deposition mechanism of CVD SiC coatings on NextelTM440 fibers, and thickness control of the coatings was actualized by varying the deposition time. The main conclusions can be summarized as follows:


Coatings composed of β-SiC and free carbon could be used for interface engineering of oxide fiber-reinforced composites. After preparation of the composites under inert atmosphere, free carbon could be oxidized to obtain porous SiC interphases, which could improve the fiber/matrix interface characteristics. Further work will focus on interface engineering of NextelTM440-reinforced mullite composite by porous SiC interphases. The damage mode and strength of the composites will be systematically investigated.

**Author Contributions:** Conceptualization, Y.W. and H.C.; Data curation, J.S. and B.S.; Investigation, Y.W., J.S. and H.C.; Methodology, Y.W. and B.S.; Writing—original draft, Y.W.; Writing—review and editing, H.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (NSFC) under Grant No. 51602347.

**Conflicts of Interest:** The authors declare no conflicts of interest.
