Microstructure and oxidation resistant property of C/C composites modified by SiC–MoSi₂–CrSi₂ coating

Abstract

To prevent carbon/carbon (C/C) composites from oxidation, a dense and multiphase inlaid SiC–MoSi₂–CrSi₂ coating was prepared by pack cementation. The coatings were characterised by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The effect of pack composition on the oxidation properties was studied on low density C/C composite, and then optimum composition was finalised. The optimum composition was the one containing 5 wt-%Cr and oxidation behaviour of high and low density C/C composites coatings with this composition was studied. Oxidation test shows that, when the Cr content was 5 wt-%, the SiC–MoSi₂–CrSi₂ coating possessed excellent oxidation resistant ability. After application of the SiC–MoSi₂–CrSi₂ multiphase coating, the low density C/C composite showed a mass loss of only 1·36% after oxidation at 1873 K for 43 h, while the mass loss of the coated high density sample was up to 7·45% after oxidation at 1873 K for 8 h.

Keywords:

• Carbon
• Composites
• Oxidation
• Coating

This work has been supported by the National Natural Science Foundation of China under grant nos. 50802075 and 50832004, and by the NPU Foundation for Fundamental Research and the Research Fund of State Key Laboratory of Solidification Processing, Xi’an, China (grant no. KP200913) and Graduate Starting Seed Fund of Northwestern Polytechnical University.