Synthesis of carbon nanotube
Carbon nanotube and carbon nanofiber can be synthesized by reacting hydrocarbon and ultra-fine metal particles, such as iron, at high temperature. The generating method of Vapor grown carbon fiber: VGCF, that discovered by professor Endo is the beginning of that method.
The synthesis method of VGCF is generally classified two kinds - substrate method and floating method. Substrate method is scatter ultra-fine metal catalyst on substrate directly, and set it in furnace tube. Then, set electric furnace to high temperature, and flow hydrocarbon gas into furnace to grow CNT.
1. Scatter metal catalyst on substrate.
2. Set substrate in furnace tube.
3. Synthesis carbon nanotube to flow in hydrocarbon gas.
Floating method is hydrocarbon and metal catalysts flow into furnace at high temperature. This method can synthesize fiber which has small diameter.
If we use one furnace, vapor and synthesis reaction are synchronous. So, carbon nanotubes not grow uniformly. As a method of solving this problem, divide vapor and synthesis reaction. Vapor catalyst and hydrocarbon in first furnace, then decompose hydrocarbon and synthesize carbon nanotube in second furnace.
