A Si-Al-lr oxidation resistant coating was prepared for SiC coated carbon/carbon composites by slurry dipping. The phase composition, microstructure and oxidation resistance of the as-prepared Si-Al-lr coating were st...A Si-Al-lr oxidation resistant coating was prepared for SiC coated carbon/carbon composites by slurry dipping. The phase composition, microstructure and oxidation resistance of the as-prepared Si-Al-lr coating were studied by XRD （X-ray diffraction）, SEM （scanning electron microscopy）, and isothermal oxidation test at 1773 K in air, respectively. The surface of the as-prepared Si-Al-lr coating was dense and the thickness was approximately 100 um. Its anti-oxidation property was superior to that of the inner SiC coating. The weight loss of SiC/Si- Al-lr coated carbon/carbon composites was less than 5 wt. pct after oxidation at 1773 K in air for 79 h. The local oxidation defects in the coating may result in the failure of the SiC/Si-Al-Ir coating.展开更多
Due to ineffectiveness of routine IR-absorption method for determinahon of intershtial oxygen in heavily doped silicon, a 'peak-height' method has been dcveloped. The phosphorus-doped CZ-Si with n=(7.l～l2)...Due to ineffectiveness of routine IR-absorption method for determinahon of intershtial oxygen in heavily doped silicon, a 'peak-height' method has been dcveloped. The phosphorus-doped CZ-Si with n=(7.l～l2)× 10~17cm^(-3) was taken as sample for characterization. The calculation results at 300 K and 10 K were ptesented in detail. The'peak-height' method is much simpler than 'short-baseline' and 'curved-baseline' methods.展开更多
Silicon and Silicon carbide particles have been investigated by the mean of infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to establish their surface states. The results of this research are bas...Silicon and Silicon carbide particles have been investigated by the mean of infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to establish their surface states. The results of this research are based on the estimation of the area under the high resolution peaks by isosceles triangles. This approach leads to the repartition of the particles surfaces in term of atomic percentage and of type of bonds. The surface of silicon particles is divided up into 54.85% of Si-O bonds and 36.85% of Si-Si bonds. The remaining surface is constituted of zeolite, the raw material used to produce the silicon particles. The surface of silicon carbide particles consists of 50.44% of Si-C bonds, 24.01% of Si-O bonds and 25.55% of graphite. 10.01% of the graphite is derived from the oxidation of Si-C bonds while 11.48% is due to contamination. The zeta potential evolution versus pH confirms the distribution of chemical groups found.展开更多
基金supported by the National "973"Project under grant No. 2006CB600908
文摘A Si-Al-lr oxidation resistant coating was prepared for SiC coated carbon/carbon composites by slurry dipping. The phase composition, microstructure and oxidation resistance of the as-prepared Si-Al-lr coating were studied by XRD （X-ray diffraction）, SEM （scanning electron microscopy）, and isothermal oxidation test at 1773 K in air, respectively. The surface of the as-prepared Si-Al-lr coating was dense and the thickness was approximately 100 um. Its anti-oxidation property was superior to that of the inner SiC coating. The weight loss of SiC/Si- Al-lr coated carbon/carbon composites was less than 5 wt. pct after oxidation at 1773 K in air for 79 h. The local oxidation defects in the coating may result in the failure of the SiC/Si-Al-Ir coating.
文摘Due to ineffectiveness of routine IR-absorption method for determinahon of intershtial oxygen in heavily doped silicon, a 'peak-height' method has been dcveloped. The phosphorus-doped CZ-Si with n=(7.l～l2)× 10~17cm^(-3) was taken as sample for characterization. The calculation results at 300 K and 10 K were ptesented in detail. The'peak-height' method is much simpler than 'short-baseline' and 'curved-baseline' methods.
文摘Silicon and Silicon carbide particles have been investigated by the mean of infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to establish their surface states. The results of this research are based on the estimation of the area under the high resolution peaks by isosceles triangles. This approach leads to the repartition of the particles surfaces in term of atomic percentage and of type of bonds. The surface of silicon particles is divided up into 54.85% of Si-O bonds and 36.85% of Si-Si bonds. The remaining surface is constituted of zeolite, the raw material used to produce the silicon particles. The surface of silicon carbide particles consists of 50.44% of Si-C bonds, 24.01% of Si-O bonds and 25.55% of graphite. 10.01% of the graphite is derived from the oxidation of Si-C bonds while 11.48% is due to contamination. The zeta potential evolution versus pH confirms the distribution of chemical groups found.
