Carbon fiber-reinforced silicon carbonitride ceramic matrix composites （C/SiCN） were prepared by rapid electro-thermal pyrolysis CVD using liquid polymer hexamethyldisilazane （HMDS, （CH3）3SiNHSi（CH3）3） as prec...Carbon fiber-reinforced silicon carbonitride ceramic matrix composites （C/SiCN） were prepared by rapid electro-thermal pyrolysis CVD using liquid polymer hexamethyldisilazane （HMDS, （CH3）3SiNHSi（CH3）3） as precursor. Microstructure morphology and production technique of C/SiCN composites were investigated. Scanning electron microscopy and transmission electron microscopy were respectively employed to characterize microstructures of the as-received C/SiCN composites samples. The high temperature pyrolysis of HMDS results in destruction of molecular chain, fracture of bonds, as well as liquid-gas-solid conversion from polymer to ceramic. Microstructures observation indicates that there is a high degree of coalescence between SiCN matrix and C fiber. The deposition model of liquid precursor electro-thermal pyrolysis CVD is different from that of gas precursor isothermal chemical vapor infiltration. Rapid liquid flow and slow gas diffusion are key factors for the difference of two methods. Preparation of rapid electro-thermal pyrolysis CVD consists of four steps including liquid polymer infiltration, polymer pyrolysis, rapid deposition of pyrolyzed substances and rapid densification, respectively.展开更多
Ⅰ. INTRODUCTIONThe preparation and application studies of diamond thin films as a new type of multifunction materials have made a great progress in recent years. Up to now, the initial applications of diamond thin fi...Ⅰ. INTRODUCTIONThe preparation and application studies of diamond thin films as a new type of multifunction materials have made a great progress in recent years. Up to now, the initial applications of diamond thin films prepared by various methods based on chemical vapor deposi-展开更多
In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catal...In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catalyst.It is confirmed that indium can catalyze the growth of Si NWs.More importantly,we found that tin generated in situ from the reduction of SnO 2 by indium can act as catalyst,which greatly enhances the growth of Si NWs on FTO substrate.The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially.This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.展开更多
Chemical vapor deposition-tungsten （CVD-W） coating covering the surface of the plasma facing component （PFC） is an effective method to implement the tungsten material as plasma facing material （PFM） in fusion de...Chemical vapor deposition-tungsten （CVD-W） coating covering the surface of the plasma facing component （PFC） is an effective method to implement the tungsten material as plasma facing material （PFM） in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method （ANSYS 10.0 code）. The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.展开更多
基金Funded by the National Natural Science Foundation of China(No.50772089)the Program of Introducing Talents of Discipline in the Project of Advanced Materials and their Forming Technology(B08040)
文摘Carbon fiber-reinforced silicon carbonitride ceramic matrix composites （C/SiCN） were prepared by rapid electro-thermal pyrolysis CVD using liquid polymer hexamethyldisilazane （HMDS, （CH3）3SiNHSi（CH3）3） as precursor. Microstructure morphology and production technique of C/SiCN composites were investigated. Scanning electron microscopy and transmission electron microscopy were respectively employed to characterize microstructures of the as-received C/SiCN composites samples. The high temperature pyrolysis of HMDS results in destruction of molecular chain, fracture of bonds, as well as liquid-gas-solid conversion from polymer to ceramic. Microstructures observation indicates that there is a high degree of coalescence between SiCN matrix and C fiber. The deposition model of liquid precursor electro-thermal pyrolysis CVD is different from that of gas precursor isothermal chemical vapor infiltration. Rapid liquid flow and slow gas diffusion are key factors for the difference of two methods. Preparation of rapid electro-thermal pyrolysis CVD consists of four steps including liquid polymer infiltration, polymer pyrolysis, rapid deposition of pyrolyzed substances and rapid densification, respectively.
文摘Ⅰ. INTRODUCTIONThe preparation and application studies of diamond thin films as a new type of multifunction materials have made a great progress in recent years. Up to now, the initial applications of diamond thin films prepared by various methods based on chemical vapor deposi-
基金supported by Solar Energy Initiative of the Knowledge Innovation Program of the Chinese Academy of Sciences (KGCX2-YW-395-3)
文摘In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catalyst.It is confirmed that indium can catalyze the growth of Si NWs.More importantly,we found that tin generated in situ from the reduction of SnO 2 by indium can act as catalyst,which greatly enhances the growth of Si NWs on FTO substrate.The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially.This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.
基金supported by the Key Project of Chinese Academy of Sciences(No.KJCX2-YW-N35)National Natural Science Foundation of China(No.11175205)
文摘Chemical vapor deposition-tungsten （CVD-W） coating covering the surface of the plasma facing component （PFC） is an effective method to implement the tungsten material as plasma facing material （PFM） in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method （ANSYS 10.0 code）. The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.
