Si–Mo–Cr coating for C/SiC coated carbon/carbon composites against oxidation

Abstract

Si–Mo–Cr oxidation protective coating has been prepared on the surface of C/SiC coated carbon/carbon (C/C) composites by pack cementation technique. The phase composition and microstructure of the as prepared coatings were characterised by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersion spectrum (EDS) analyses. The oxidation behaviour of the coated C/C specimens was also investigated at 1500°C in air. The results show that the as prepared coating is mainly composed of SiC, MoSi₂, CrSi₂ and Si. The coating characterised by excellent oxidation resistance and thermal shock resistance can effectively protect C/C composites from oxidation for 186 h at 1500°C in air and endure the thermal cycle between 1500°C and room temperature for nine times, while the corresponding weight loss is only 0·33%. The excellent oxidation protection ability of the coating is primarily attributed to the formation of a compound glass layer, including SiO₂ and Cr₂O₃.

Keywords:

• Composites
• Oxidation
• Coating

This work was supported by the National Natural Science Foundation of China under grant nos. 50902111 and 50972120, and NPU Foundation for Fundamental Research and the Research Fund of the State Key Laboratory of Solidification Processing (NWPU), China (grant no. 73-QP-2010), and supported by Shenzhen Key Laboratory of Special Functional Materials in Shenzhen University under grant no. T201010.