To protect carbon materials from oxidation,SiC coatings were prepared on carbon/carbon(C/C)composites and graphite by chemical vapor reaction.SEM and XRD analyses show that the coatings obtained are composed of SiC gr...To protect carbon materials from oxidation,SiC coatings were prepared on carbon/carbon(C/C)composites and graphite by chemical vapor reaction.SEM and XRD analyses show that the coatings obtained are composed of SiC grains and micro-crystals. The influence of different carbon substrates on oxidation behavior of coated samples was investigated,and then their oxidation mechanisms were studied.Oxidation test shows that the SiC coated graphite has a better oxidation resistance than SiC coated C/C composites at high temperatures(1 623 K and 1 823 K).In the oxidation process,the oxidation curves of SiC coated C/C composites are linear,while those of SiC coated graphite follow a quasi-parabolic manner.The oxidation mechanism of the former is controlled by chemical reaction while the latter is controlled by oxygen diffusion based on the experimental results.The variation of oxidation behavior and mechanism of SiC coatings on two kinds of carbon substrates are primarily contributed to their structure differences.展开更多
To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by...To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by chemical vapor reaction (CVR): a simple and cheap technique to prepare the SiC coating via siliconizing the substrate that was exposed to the mixed vapor (Si and SiO2) at high temperatures (1 923?2 273 K). Then the as-prepared coating was processed by a dipping and drying procedure with tetraethoxysilane as source materials to form SiO2 to fill the cracks and holes. Oxidation tests show that, after oxidation in air at 1 623 K for 10 h and thermal cycling between 1 623 K and room temperature 5 times, the mass loss of the CVR coated sample is up to 18.21%, while the sample coated with modified coating is only 5.96%, exhibiting an obvious improvement of oxidation and thermal shock resistance of the coating. The mass loss of the modified sample is mainly contributed to the reaction of C/C substrate with oxygen diffusing through the penetrating cracks formed in thermal shock tests.展开更多
TQ174.558.23 94064102脉冲CO<sub>2</sub>激光制备纳米级SiC粉末=Pulsed CO<sub>2</sub>laser assisted synthesis of nanometer SiC ceramic powder[刊,中]/韩理,于威,傅广生,李晓苇,张连水（河北大学物理系...TQ174.558.23 94064102脉冲CO<sub>2</sub>激光制备纳米级SiC粉末=Pulsed CO<sub>2</sub>laser assisted synthesis of nanometer SiC ceramic powder[刊,中]/韩理,于威,傅广生,李晓苇,张连水（河北大学物理系.河北,保定（071002））//中国激光.—1994,A21（6）.—522—525采用脉冲TEACO<sub>2</sub>激光诱发SiH<sub>4</sub>+CH<sub>4</sub>等离子体化学气相反应,合成了粒度分布均匀的纳米SiC球型陶瓷粉末,采用傅里叶红外光谱、X射线衍射。展开更多
基金Project(2006CB600901)supported by the National Basic Research Program of ChinaProjects(50772134,50802115)supported by the National Natural Science Foundation of China
文摘To protect carbon materials from oxidation,SiC coatings were prepared on carbon/carbon(C/C)composites and graphite by chemical vapor reaction.SEM and XRD analyses show that the coatings obtained are composed of SiC grains and micro-crystals. The influence of different carbon substrates on oxidation behavior of coated samples was investigated,and then their oxidation mechanisms were studied.Oxidation test shows that the SiC coated graphite has a better oxidation resistance than SiC coated C/C composites at high temperatures(1 623 K and 1 823 K).In the oxidation process,the oxidation curves of SiC coated C/C composites are linear,while those of SiC coated graphite follow a quasi-parabolic manner.The oxidation mechanism of the former is controlled by chemical reaction while the latter is controlled by oxygen diffusion based on the experimental results.The variation of oxidation behavior and mechanism of SiC coatings on two kinds of carbon substrates are primarily contributed to their structure differences.
基金Project(2006CB600901) supported by the National Basic Research Program of ChinaProject(50802115) supported by the National Natural Science Foundation of China
文摘To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by chemical vapor reaction (CVR): a simple and cheap technique to prepare the SiC coating via siliconizing the substrate that was exposed to the mixed vapor (Si and SiO2) at high temperatures (1 923?2 273 K). Then the as-prepared coating was processed by a dipping and drying procedure with tetraethoxysilane as source materials to form SiO2 to fill the cracks and holes. Oxidation tests show that, after oxidation in air at 1 623 K for 10 h and thermal cycling between 1 623 K and room temperature 5 times, the mass loss of the CVR coated sample is up to 18.21%, while the sample coated with modified coating is only 5.96%, exhibiting an obvious improvement of oxidation and thermal shock resistance of the coating. The mass loss of the modified sample is mainly contributed to the reaction of C/C substrate with oxygen diffusing through the penetrating cracks formed in thermal shock tests.
文摘TQ174.558.23 94064102脉冲CO<sub>2</sub>激光制备纳米级SiC粉末=Pulsed CO<sub>2</sub>laser assisted synthesis of nanometer SiC ceramic powder[刊,中]/韩理,于威,傅广生,李晓苇,张连水（河北大学物理系.河北,保定（071002））//中国激光.—1994,A21（6）.—522—525采用脉冲TEACO<sub>2</sub>激光诱发SiH<sub>4</sub>+CH<sub>4</sub>等离子体化学气相反应,合成了粒度分布均匀的纳米SiC球型陶瓷粉末,采用傅里叶红外光谱、X射线衍射。
