The stability range of primary spacing of the tilted dendritic arrays in directional solidification has been studied by quantitative phase-field simulations. Results show that both the real growth direction and morpho...The stability range of primary spacing of the tilted dendritic arrays in directional solidification has been studied by quantitative phase-field simulations. Results show that both the real growth direction and morphological shapes of dendritic arrays change with the primary spacing for different misorientation angles(θ0). It has been found that the lower limit of primary spacing is independent of θ0, but the upper limit of primary spacing is strongly influenced by that. The two kinds of tertiary branching instabilities result in different behaviors of the variation of the upper limit with misorientation angle for different pulling velocities.展开更多
A strategy to prepare horizontally aligned single-walled carbon nanotubes(SWNTs) at moderate temperatures(≤600 ℃) were developed.Using ferocene as the catalyst precursor,Fe nanoparticles are formed in the gaseous ph...A strategy to prepare horizontally aligned single-walled carbon nanotubes(SWNTs) at moderate temperatures(≤600 ℃) were developed.Using ferocene as the catalyst precursor,Fe nanoparticles are formed in the gaseous phase and catalyze the nucleation and growth of SWNTs in situ.Then the resultant SWNTs are deposited onto the substrates downstream and aligned by the surface lattice of the ST-cut single crystal quartz.The preparation of SWNT arrays at moderate temperatures is important for combining the tube growth with device fabrication.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61078057 and 51172183)the Natural Science Foundation of Shaanxi Province in China(Grant No.2012JQ8013)+1 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.3102014KYJD026 and JC20120246)the grant from the Program of New Staff and Research Area Project of NPU(Grant No.13GH014602)
文摘The stability range of primary spacing of the tilted dendritic arrays in directional solidification has been studied by quantitative phase-field simulations. Results show that both the real growth direction and morphological shapes of dendritic arrays change with the primary spacing for different misorientation angles(θ0). It has been found that the lower limit of primary spacing is independent of θ0, but the upper limit of primary spacing is strongly influenced by that. The two kinds of tertiary branching instabilities result in different behaviors of the variation of the upper limit with misorientation angle for different pulling velocities.
基金supported by Ministry of Science and Technology of China(2016YFA0201904)the National Natural Science Foundation of China(21631002,U1632119)
文摘A strategy to prepare horizontally aligned single-walled carbon nanotubes(SWNTs) at moderate temperatures(≤600 ℃) were developed.Using ferocene as the catalyst precursor,Fe nanoparticles are formed in the gaseous phase and catalyze the nucleation and growth of SWNTs in situ.Then the resultant SWNTs are deposited onto the substrates downstream and aligned by the surface lattice of the ST-cut single crystal quartz.The preparation of SWNT arrays at moderate temperatures is important for combining the tube growth with device fabrication.
