Oxidation Protective C/SiC/Si-SiC Multilayer Coating for Carbon/Carbon Composites Applying at 1873 K

Yulei Zhang,Hejun Li,Xinfa Qiang and Kezhi Li C/C Composites Research Center,State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi an 710072,China

Õª Òª£ºA C/SiC/Si-SiC multilayer coating for protecting carbon/carbon£¨C/C£© composites against oxidation was prepared by slurry and pack cementation.X-ray diffraction£¨XRD£© and energy dispersive spectroscopy£¨EDS£© analysis showed that the inner coating obtained from the slurry and pack cementation was a C/SiC gradient layer acting as bonding layer,and the exterior coating formed in the second pack cementation was a Si-SiC double phase coating.Oxidation tests at 1873 K in air showed that the coating exhibited excellent oxidation protective ability and thermal shock resistance.The coating could effectively protect C/C composites from oxidation at 1873 K in air for 170 h and undergo the thermal cycling between 1873 K and room temperature for 8 cycles.The weight loss of the coated C/C composites is due to the formation of cracks and holes in the coating and the volatilization of SiO2 glass at high temperature.

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