GROWING CARBON-FIBERS WITH A LINEARLY INCREASING TEMPERATURE SWEEP - EXPERIMENTS AND MODELING

被引:39
作者
TIBBETTS, GG
机构
[1] Physics Department, General Motors Research Laboratories, Warren
关键词
VAPOR-GROWN CARBON FIBERS; GROWTH OF CARBON FIBERS; CATALYTIC GROWTH OF CARBON; FILAMENTOUS CARBON; CARBON FILAMENTS;
D O I
10.1016/0008-6223(92)90037-W
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Carbon fibers may be grown from iron catalyst particles with good yield in methane-hydrogen mixtures by ramping the temperature at a constant rate through a well-defined range. The regimen which yields the highest mass of fibers uses a methane concentration of 16%, gas residence time of 4 minutes, and a temperature increase of 7.1-degrees/min. starting at 950-degrees-C and ending at the thickening temperature of 1120-degrees-C. Despite a lengthening duration of only 24 minutes, which produces rather short fibers, this regimen yields a greater mass of fibers than one in which the temperature is increased more slowly. High yield is achieved by causing more fibers to grow per unit area. Methane concentrations below the optimum grow longer, sparser fibers; methane concentrations above the optimum give shorter, densely growing fibers. The experimental fiber lengths may be modelled by assuming that the fiber-lengthening rate is proportional to the square of the methane concentrations, and that the catalytic particles are poisoned by hydrocarbon burial. The number of fibers grown per unit area may be modelled with an expression that describes surface sintering of the catalyst particles.
引用
收藏
页码:399 / 406
页数:8
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