Preparation of a SiC/Cristobalite-AlPO_4 Multi-layer Protective Coating on Carbon/Carbon Composites and Resultant Oxidation Kinetics and Mechanism  

作　　者：Jianfeng Huang Wendong Yang Liyun Cao 

机构地区：[1]Key Laboratory of Auxiliary Chemistry & Technology for Chemical Industry, Ministry of Education, Shaanxi University of Science & Technology, Xi'an 710021, China [2]Laboratory of Opto-Functional Materials and Photochemistry, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China

出　　处：《Journal of Materials Science & Technology》2010年第11期1021-1026,共6页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No. 50772063);the Foundation of New Century Excellent Talent in University of China (Grant No. NCET-06-0893);the Doctorate Research Foundation of Ministry of Education of China(Grant No. 20070708001);the Graduate Innovation Fund of SUST

摘　　要：In order to improve the oxidation resistance of carbon/carbon （C/C） composites,a SiC/C-AlPO4 multi-layer coating was fabricated on the C/C composites by a simple and low-cost method.The internal SiC bonding layer was prepared by a two-step pack cementation process and the external C-AlPO4 coating was deposited by hydrothermal electrophoretic deposition process.Phase compositions and microstructures of the as-prepared multi-layer coating were characterized by X-ray diffraction （XRD）,scaning electron microspocy （SEM） and energy dispersive spectrometer （EDS）.Anti-oxidation properties,oxidation behavior and the failure behavior of the coated composites were investigated.The results indicate that the multi-layer coating exhibits obviously two-layer structure.The inner layer is composed of β-SiC,α-SiC phase with a scale of silicon phase.The outer layer is composed of cristobalite aluminum phosphate （C-AlPO4） crystallites.The SEM observation shows the good bonding between the inner and outer layers.The multi-layer coating displays an excellent oxidation resistance in air in the temperature range from 1573 to 1773 K,and the corresponding oxidation activation energy of the coated C/C composites is calculated to be 117.2 kJ/mol.The oxidation process is predominantly controlled by the diffusion of O2 through the C-AlPO 4 coating.The failure of the multi-layer coating results from the generation of the microholes that may be left by the escape of the oxidation gases.In order to improve the oxidation resistance of carbon/carbon （C/C） composites,a SiC/C-AlPO4 multi-layer coating was fabricated on the C/C composites by a simple and low-cost method.The internal SiC bonding layer was prepared by a two-step pack cementation process and the external C-AlPO4 coating was deposited by hydrothermal electrophoretic deposition process.Phase compositions and microstructures of the as-prepared multi-layer coating were characterized by X-ray diffraction （XRD）,scaning electron microspocy （SEM） and energy dispersive spectrometer （EDS）.Anti-oxidation properties,oxidation behavior and the failure behavior of the coated composites were investigated.The results indicate that the multi-layer coating exhibits obviously two-layer structure.The inner layer is composed of β-SiC,α-SiC phase with a scale of silicon phase.The outer layer is composed of cristobalite aluminum phosphate （C-AlPO4） crystallites.The SEM observation shows the good bonding between the inner and outer layers.The multi-layer coating displays an excellent oxidation resistance in air in the temperature range from 1573 to 1773 K,and the corresponding oxidation activation energy of the coated C/C composites is calculated to be 117.2 kJ/mol.The oxidation process is predominantly controlled by the diffusion of O2 through the C-AlPO 4 coating.The failure of the multi-layer coating results from the generation of the microholes that may be left by the escape of the oxidation gases.

关 键 词：Carbon/carbon composites Aluminum phosphate Hydrothermal electrophoretic deposition COATINGS OXIDATION 

分 类 号：TQ352.1[化学工程] TB332[一般工业技术—材料科学与工程]