A pressure enhanced CVD method for large scale synthesis of carbon microtubes and their mechanical properties

Carbon microtubes (CMTs) are a new morphological form of carbon with micrometer scale internal diameters and thin walls made of a few graphitic layers. However, compared with carbon nanotubes, there is lack of a feasible and reliable synthetic method. Furthermore, the mechanical properties of CMTs have not been reported. In this paper, we report a gas pressure enhanced CVD method for large-scale preparation of high-purity, crystalline and thin-walled CMTs in a gas pressure furnace using urea as raw material in the absence of catalyst. The as-obtained CMTs have highly graphitized structure and have a homogenous morphology with an internal diameter of about 1 μm, a wall thickness of 5 nm and several millimeters in length. The Young's modulus of the CMTs was determined to be 0.652 TPa on average, which is comparable to that of carbon nanotubes reported in previous research.