Preparation of nano-scale Cr3C2 particles dispersed on alumina particles by MOCVD in fluidized reactor and carbothermal treatment

Nano-scale Cr3C2 powder with an average particle size of 50-80 nm, uniformly coated on alumina particles, has been prepared by metal organic chemical vapor deposition (MOCVD) in the fluidized chamber, using the pyrolysis of Cr(CO)6 precursor, and carbothermal treatment in the CH4 and H2 gas mixtures. The Cr(CO)6 precursor was characterized by differential scanning calorimetry (DSC) to understand the decomposition temperature of the precursor, which was determined to be 163 °C. The precursor decomposed and formed the mixture of CrC1 − x, Cr2O3 and free carbon on the surface of the Al2O3 particles when pyrolyzed in fluidized bed at 300 and 400 °C. The resultant powders were examined by X-ray diffractometer (XRD) and transmission electron microscopy (TEM) equipped with energy dispersion spectrometer (EDS), for investigating phase composition and microstructures. The as-deposited particles fabricated at 300 and 400 °C in fluidized chamber were amorphous and crystalline, respectively. The thermal behaviour investigated by TG/DTA indicates that the amorphous powder had a exothermic peak in the DTA curve at ∼400 °C, which crystallized at this temperature. In order to prepare the nano-particle reinforced composites, the powder fabricated in the fluidized bed was carbonized in the mixed atmosphere of CH4 and H2. Both CrC1 − x and Cr2O3 phase were transferred into Cr3C2 phase after the carbothermal treatment.