Jinjiang YU
,
Jun ZHANG
,
Hengzhi FU
,
Jinchen ZHAO
材料科学技术（英）
Microstructure Characteristic of Ni-Nb near eutectic alloy is systematically investigated during directional solidification with electron beam floating zone melting (EBFZM). The effect of the Zone melting rate on the microstructure has also been studied.
关键词:
Xiaotao LIU
,
Jianzhong CUI
,
Yanhui GUO
,
Xiaoming WU
,
Jun ZHANG
材料科学技术（英）
The influence of an alternative magnetic field on the growth of the diffusion of Al and Mg in Al-Mg diffusion couple is studied. The diffusion zone is composed of two intermediate phases, namely β and γ phase. Thickness of each intermediate phase is examined. The results show that the alternative magnetic field increase the thicknesses of β and γ phase zone and the layer growth of β and γ phase obeys the parabolic rate law. The growth rate of the β and γ phase are increased with the application of the alternative magnetic field. This change is manifested through a change in the frequency factor k0 and not through a change in the activation energy Q. The frequency factor k0 for intermediate phase growth with an alternative magnetic field is 39.95 cm2/s for γ phase and 2.84×10-4 cm2/s for β phase compared with those without the magnetic field is 22.4 cm2/s for γ phase and 1.53×10-4 cm2/s for β phase.
关键词:
Alternative magnetic field
,
null
,
null
,
null
,
null
Xiang QI
,
Jun ZHANG
材料科学技术（英）
The substrate pre-treatment plays a key role in obtaining hollow-cored carbon nanotubes (CNTs) and solidcored carbon nanofibers (CNFs) from flames. This paper introduces a simply and high-efficient process by coating a NiSO4 or FeSO4 layer on the substrate as catalyst precursors. Comparing with the regular pretreatment methods, the present experiments showed that the coating pre-treatment provided the following advantages: 1) greatly shortening the synthesis time; 2) available variant substrates and carbon sources; 3) narrowing the diameters distribution. The sulfate is considered to be a crucial factor at the growth of CNTs and CNFs, because it increases the surface energy of catalyst particles and the surface specificity of sulfurs action in metallic grains. This novel process provides a possibility for high quality and mass production of CNTs and CNFs from flames.
关键词:
Carbon nanotubes
,
nanotubes
,
carbon
,
nanofibers
,
flam
