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The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes(MWCNTs) by directly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ℃ are investigated with the aid of X-ray diffraction(XRD),scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM) and thermogravimetry-differential scanning calorimetry(TG-DSC).The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ℃ to 1200 ℃.An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ℃.Up to 1500 ℃,nearly all the MWCNTs transformed into SiC nanowires.The oxidation resistance of the treated MWCNTs was improved compared with as-received ones.Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol,much higher than 164 kJ/mol of as-received ones.
The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes (MWCNTs) by directly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ° C are investigated with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM ), high resolution transmission electron microscopy (HRTEM) and thermogravimetry-differential scanning calorimetry (TG-DSC). The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ° C. to 1200 ° C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ° C. Up to 1500 ° C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared to as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ / mol, much higher than 164 kJ / mol of as-received ones.