SiC continuous fiber-reinforced pure Ti(TA1)matrix composites were fabricated by a vacuum hot pressing(VHP)methodand then heat-treated in vacuum under different conditions.The interfacial reaction and the formation of...SiC continuous fiber-reinforced pure Ti(TA1)matrix composites were fabricated by a vacuum hot pressing(VHP)methodand then heat-treated in vacuum under different conditions.The interfacial reaction and the formation of interfacial phases werestudied by using SEM,EDS and XRD.The results show that there exists reaction diffusion at the interface of SiC fibers and Timatrix,and the concentration fluctuation of reaction elements such as C,Ti and Si appears in interfacial reaction layer.The interfacialreaction products are identified as Ti3SiC2,TiCx and Ti5Si3Cx.At the beginning of interfacial reaction,the interfacial reactionproducts are TiCx and Ti5Si3Cx.Along with the interfacial reaction diffusion,Ti3SiC2 and Ti5Si3Cx single-phase zones come forth inturn adjacent to SiC fibers,and the TiC+Ti5Si3Cx double-phase zone appears adjacent to Ti matrix,which forms discontinuousconcentric rings by turns around the fibers.The formed interfacial phases are to be Ti3SiC2,Ti5Si3Cx and TiCx+Ti5Si3Cx from SiCfiber to Ti matrix.The interfacial reaction layer growth is controlled by diffusion and follows a role of parabolic rate,and theactivation energy(Qk)and(k0)of SiC/TA1 are 252.163 kJ/mol and 7.34×10?3m/s1/2,respectively.展开更多
The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interfa...The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interface can exist in large amounts of crystalline or amorphous states.However,the experimental evidence of coexistence of liquid water phases at interface is still insufficient.Here,a special folding few-layers graphene film was elaborate prepared to form a hydrophobic/hydrophobic interface,which can provide a suited platform to study the structure and properties of confined liquid water.The real-space visualization of intercalated water layers phases at the folding interface is obtained using advanced atomic force microscopy(AFM).The folding graphene interface displays complicated internal interfacial characteristics.The intercalated water molecules present themselves as two phases,low-density liquid(LDL,solid-like)and high-density liquid(HDL,liquid-like),according to their specific mechanical properties taken in two multifrequency-AFM(MF-AFM)modes.Furthermore,the water molecules structural evolution is demonstrated in a series of continuous MF-AFM measurements.The work preliminary confirms the existence of two liquid phases of water in real space and will inspire further experimental work to deeply understanding their liquid dynamics behavior.展开更多
基金Project(50371069)supported by the National Natural Science Foundation of ChinaProject(20030699013)supported by the StateEducation Ministry Doctoral Foundation of ChinaProject(04G53044)supported by the Foundation of Aviation Science of China
文摘SiC continuous fiber-reinforced pure Ti(TA1)matrix composites were fabricated by a vacuum hot pressing(VHP)methodand then heat-treated in vacuum under different conditions.The interfacial reaction and the formation of interfacial phases werestudied by using SEM,EDS and XRD.The results show that there exists reaction diffusion at the interface of SiC fibers and Timatrix,and the concentration fluctuation of reaction elements such as C,Ti and Si appears in interfacial reaction layer.The interfacialreaction products are identified as Ti3SiC2,TiCx and Ti5Si3Cx.At the beginning of interfacial reaction,the interfacial reactionproducts are TiCx and Ti5Si3Cx.Along with the interfacial reaction diffusion,Ti3SiC2 and Ti5Si3Cx single-phase zones come forth inturn adjacent to SiC fibers,and the TiC+Ti5Si3Cx double-phase zone appears adjacent to Ti matrix,which forms discontinuousconcentric rings by turns around the fibers.The formed interfacial phases are to be Ti3SiC2,Ti5Si3Cx and TiCx+Ti5Si3Cx from SiCfiber to Ti matrix.The interfacial reaction layer growth is controlled by diffusion and follows a role of parabolic rate,and theactivation energy(Qk)and(k0)of SiC/TA1 are 252.163 kJ/mol and 7.34×10?3m/s1/2,respectively.
基金the Ministry of Science and Technology(MOST)of China(No.2016YFA0200700)the National Natural Science Foun-dation of China(NSFC)(Nos.21622304,61674045,and 11604063)+1 种基金the Strategic Priority Research Program,the Key Research Program of Frontier Sciences and Instrument Developing Project of Chinese Academy of Sciences(CAS)(Nos.XDB30000000,QYZDB-SSW-SYS031,and YZ201418)Z.H.Cheng was supported by Distinguished Technical Talents Project and Youth Innovation Promotion Association CAS,the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No.18XNLG01).
文摘The phase behavior of water is a topic of perpetual interest due to its reinai kable anomalous properties and importance to biology,material science,geoscience,nanoscience,etc.It is predicted confined water at interface can exist in large amounts of crystalline or amorphous states.However,the experimental evidence of coexistence of liquid water phases at interface is still insufficient.Here,a special folding few-layers graphene film was elaborate prepared to form a hydrophobic/hydrophobic interface,which can provide a suited platform to study the structure and properties of confined liquid water.The real-space visualization of intercalated water layers phases at the folding interface is obtained using advanced atomic force microscopy(AFM).The folding graphene interface displays complicated internal interfacial characteristics.The intercalated water molecules present themselves as two phases,low-density liquid(LDL,solid-like)and high-density liquid(HDL,liquid-like),according to their specific mechanical properties taken in two multifrequency-AFM(MF-AFM)modes.Furthermore,the water molecules structural evolution is demonstrated in a series of continuous MF-AFM measurements.The work preliminary confirms the existence of two liquid phases of water in real space and will inspire further experimental work to deeply understanding their liquid dynamics behavior.
