To improve the oxidation resistance of carbon/carbon composites,ZrB2-MoSi2/SiC coating on the carbon/carbon substrate was prepared.The inner coating of SiC was prepared by pack cementation and the outer coating of ZrB...To improve the oxidation resistance of carbon/carbon composites,ZrB2-MoSi2/SiC coating on the carbon/carbon substrate was prepared.The inner coating of SiC was prepared by pack cementation and the outer coating of ZrB2-MoSi2 was prepared by slurry painting.The phase compositions and microstructures of the coating were characterized by XRD and SEM,respectively.The preparation and the high temperature oxidation property of the coated composites were investigated.The results show that the outer coating of carbon/carbon composites is composed of ZrB2,MoSi2 and SiC phases.The mass losses of the ZrB2-MoSi2/SiC coated samples with SiC nano-whiskers after 30 h and 10 h of oxidation at 1 273 K and 1 773 K were,respectively,5.3% and 3.0%.The ZrB2-MoSi2/SiC coated samples exhibit self-sealing performance and good oxidation resistance at high temperature.展开更多
C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the...C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.展开更多
In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C com...In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C composites, and then MoSi2 and SiC were subsequently prepared in a CVI /CVR process using methyltrichlorosilane （MTS） as precursor. The deposition and reaction mechanism of the MoSi2-SiC composite coating was investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The oxidation behavior of SiC-MoSi2 coated specimens was tested. The results show that the porous Mo layer can be densified with SiC phase decomposed from MTS, and transformed into SiC-MoSi2 by reacting with MTS as well. A dense composite coating was prepared with optimized deposition parameters. The coated specimen exhibits a good oxidation resistance with a little mass loss of 1.25% after oxidation at 1500 °C for 80 h.展开更多
采用两段式包埋法工艺可制得涂层结构合理的复合梯度涂层,从里到外涂层结构为:S iC过渡层→S iC致密层→M oS i2/S iC双相层→以M oS i2为主的外层。随着制备工艺中高温阶段保温时间的延长,涂层表面以M oS i2为主的薄层越连续。涂层与...采用两段式包埋法工艺可制得涂层结构合理的复合梯度涂层,从里到外涂层结构为:S iC过渡层→S iC致密层→M oS i2/S iC双相层→以M oS i2为主的外层。随着制备工艺中高温阶段保温时间的延长,涂层表面以M oS i2为主的薄层越连续。涂层与基体的结合以化学结合为主,并有机械结合,结合强度高。用正硅酸四乙酯对涂层表面进行封闭处理,凝胶形成的S iO2可充填涂层表面裂纹并覆盖在涂层表面。在1 500℃高温空气中氧化,未封闭处理的涂层试样表现为氧化失重,封闭处理后的试样氧化增重。展开更多
基金Project(50721003) supported by the Innovation Community Foundation of National Natural Science of ChinaProject(2011CB605805) supported by the National Basic Research Program of China
文摘To improve the oxidation resistance of carbon/carbon composites,ZrB2-MoSi2/SiC coating on the carbon/carbon substrate was prepared.The inner coating of SiC was prepared by pack cementation and the outer coating of ZrB2-MoSi2 was prepared by slurry painting.The phase compositions and microstructures of the coating were characterized by XRD and SEM,respectively.The preparation and the high temperature oxidation property of the coated composites were investigated.The results show that the outer coating of carbon/carbon composites is composed of ZrB2,MoSi2 and SiC phases.The mass losses of the ZrB2-MoSi2/SiC coated samples with SiC nano-whiskers after 30 h and 10 h of oxidation at 1 273 K and 1 773 K were,respectively,5.3% and 3.0%.The ZrB2-MoSi2/SiC coated samples exhibit self-sealing performance and good oxidation resistance at high temperature.
基金Projects(51272213,51221001)supported by the National Natural Science Foundation of ChinaProject(73-QP-2010)supported by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)Project(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.
基金Projects(51221001,51272213,51072166)supported by the National Natural Science Foundation of ChinaProject(GBKY1021)supported by the Fundamental Research Foundation of Northwestern Polytechnical University,ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C composites, and then MoSi2 and SiC were subsequently prepared in a CVI /CVR process using methyltrichlorosilane （MTS） as precursor. The deposition and reaction mechanism of the MoSi2-SiC composite coating was investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The oxidation behavior of SiC-MoSi2 coated specimens was tested. The results show that the porous Mo layer can be densified with SiC phase decomposed from MTS, and transformed into SiC-MoSi2 by reacting with MTS as well. A dense composite coating was prepared with optimized deposition parameters. The coated specimen exhibits a good oxidation resistance with a little mass loss of 1.25% after oxidation at 1500 °C for 80 h.
文摘采用两段式包埋法工艺可制得涂层结构合理的复合梯度涂层,从里到外涂层结构为:S iC过渡层→S iC致密层→M oS i2/S iC双相层→以M oS i2为主的外层。随着制备工艺中高温阶段保温时间的延长,涂层表面以M oS i2为主的薄层越连续。涂层与基体的结合以化学结合为主,并有机械结合,结合强度高。用正硅酸四乙酯对涂层表面进行封闭处理,凝胶形成的S iO2可充填涂层表面裂纹并覆盖在涂层表面。在1 500℃高温空气中氧化,未封闭处理的涂层试样表现为氧化失重,封闭处理后的试样氧化增重。
