Effects of carbonization temperature on the microstructure and electrical conductivity of bamboo charcoal

Five year old bamboo was carbonized under N_2 atmosphere. The effect of carbonization temperature on microstructure, elemental content and resistance were investigated by TGA, SEM, EDXA and XRD. Results show that shrinkage of bamboo during carbonization increases with increasing carbonization temperature, the section shrinkage is 21%, 38% and 40% for 500℃, 750℃ and 1000℃ respectively. The microcrystalline structure of bamboo charcoal tends to a transitional state that leads to graphite. The carbon content and resistance of bamboo charcoal depend on carbonization temperature and radial location. The carbon content of bamboo charcoal carbonized at 500℃ increases from the outer to inner surfaces. An abrupt decrease of resistance is found at 750℃, which shows a 98 to 187 times decrease from outer to inner surface as compared with those values at 500℃. The electrical conductivity of the charcoal is directly related to the carbonization temperature because increasing carbonization temperature increases the crystallite size and decreases ash content, both of which are favorable for increasing the conductivity.