Effect of graphitization on the kinetics and mechanism of thermal oxidation of carbon microcoils

Carbon microcoils were prepared by catalytic chemical vapor deposition,using acetylene as carbon source,Ni powder as catalyst,and a sulfur-containing compound (thiophene) as growth promoter. The microcoils were graphitized under an argon atmosphere at 2 500 ℃. The morphology and microstructure of the oxidized carbon microcoils were investigated by scanning electron microscopy,and their oxidation resistance was studied by thermogravimetric analysis. Results reveal that oxidation resistance of the carbon microcoils is improved through graphitization,and the graphitized carbon microcoils retain their microcoil morphology after oxidation. Oxidation is a first order reaction and the activation energies are 263 and 297 kJ/mol before and after graphitization,respectively.