Xq. Chen et al., High-temperature heat treatment of carbon microcoils obtained by chemical vapor deposition process and their properties, J MATER RES, 15(3), 2000, pp. 808-814
Carbon microcoils obtained by the catalytic pyrolysis of acetylene at 770 d
egrees C were heat treated at 3000 degrees C for 6 h in a CO + CO2 atmosphe
re. The effect of the heat treatment on the morphology, microstructure, and
properties was examined. The coiling morphology of the carbon coils was al
most preserved even after the heat treatment, though it became brittle, The
ruptured cross section of the two fibers, which form the coils, generally
has either a trigonal pyramidlike form or negative pyramidal hallow. These
characteristic ruptured patterns demonstrate the growth mechanism of the ca
rbon coils. Distinct graphite layers (d = 0.339 nm) were developed by the h
eat treatment with an inclination of 10-40 degrees versus the fiber axis to
form a "herringbone" structure. The bulk electrical resistivity, density,
and specific surface area were 10-0.1 Ohm cm, 2.2077-2.087 g/cm(3), and 6-8
m(2)/g, respectively.