Theoretical consideration was conducted on a relation between pore diameter and interfacialarea between pores and fibers when pores uniforinly distribute in C/C composites. It was shownthat bonding at the fiber/matrix...Theoretical consideration was conducted on a relation between pore diameter and interfacialarea between pores and fibers when pores uniforinly distribute in C/C composites. It was shownthat bonding at the fiber/matrix interface apparently decreased with decreasing a pore diameter,and consequently a new idea of microspace modification concept was proposed for controllingfracture behavior of C/C composites. Four types of C/C composites with various pore structureswere fabricated by hot-pressing, and their fracture behavior was investigated by three pointbending tests. The fracture behavior of the C/C composites was changed from brittle one topseudo ductile one with decreasing the pore diameter. This result supported the validity of themicrospace modification concept proposed in this paper.展开更多
Using carbon nanotubes as nanobarriers,the growth of single-walled carbon nanotubes(SWNTs)on a quartz surface can be terminated.First,carbon nanotube nanobarriers were grown on a quartz surface by the gas ow-directed...Using carbon nanotubes as nanobarriers,the growth of single-walled carbon nanotubes(SWNTs)on a quartz surface can be terminated.First,carbon nanotube nanobarriers were grown on a quartz surface by the gas ow-directed growth mode.Then,the SWNTs were grown on the quartz surface via the lattice-oriented growth mode,in which growth of SWNTs can be terminated by hitting the nanotube nanobarriers.Moreover,using the carbon nanotube nanobarrier as a marker,the mechanism of the growth of SWNTs on the quartz surface can be studied;a base-growth mechanism is indicated.Based on this termination process and the base-growth mechanism,SWNT arrays with controlled lengths can be grown on a quartz surface by xing the sites of bothcatalysts and nanobarriers.展开更多
文摘Theoretical consideration was conducted on a relation between pore diameter and interfacialarea between pores and fibers when pores uniforinly distribute in C/C composites. It was shownthat bonding at the fiber/matrix interface apparently decreased with decreasing a pore diameter,and consequently a new idea of microspace modification concept was proposed for controllingfracture behavior of C/C composites. Four types of C/C composites with various pore structureswere fabricated by hot-pressing, and their fracture behavior was investigated by three pointbending tests. The fracture behavior of the C/C composites was changed from brittle one topseudo ductile one with decreasing the pore diameter. This result supported the validity of themicrospace modification concept proposed in this paper.
基金by the National Science Foundation of China(20673004,20725307,and 50821061)Ministry of Science and Technology of China(2006CB932701,2006CB932403,and 2007CB936203).C.Q.Feng acknowledges Mr.L.M.Xie(Peking University)for his useful discussion.
文摘Using carbon nanotubes as nanobarriers,the growth of single-walled carbon nanotubes(SWNTs)on a quartz surface can be terminated.First,carbon nanotube nanobarriers were grown on a quartz surface by the gas ow-directed growth mode.Then,the SWNTs were grown on the quartz surface via the lattice-oriented growth mode,in which growth of SWNTs can be terminated by hitting the nanotube nanobarriers.Moreover,using the carbon nanotube nanobarrier as a marker,the mechanism of the growth of SWNTs on the quartz surface can be studied;a base-growth mechanism is indicated.Based on this termination process and the base-growth mechanism,SWNT arrays with controlled lengths can be grown on a quartz surface by xing the sites of bothcatalysts and nanobarriers.
