Investigation on carbonizing behaviors of nanometer-sized Cr2O3 particles on alumina particles by metalorganic chemical vapor deposition in fluidized bed
Journal
Journal of Materials Research
Journal Volume
20
Journal Issue
8
Pages
2154-2160
Date Issued
2005
Author(s)
Abstract
Nanoscaled Cr2O3 powder with an average particle size of 20–40 nm, coated on alumina particles, has been produced by means of chemical vapor deposition (CVD) in a fluidized chamber, using the pyrolysis of Cr(CO)6 precursor. Amorphous and crystalline Cr2O3 particles were obtained when the temperatures of the pyrolysis were 300 and 400 °C, respectively. To prepare nanoscaled Cr3C2 powder from the nanometer-sized Cr2O3, carbonizing behavior of the Cr2O3 particles was investigated. It was found that, when amorphous Cr2O3 powders were carbonized in graphite furnace at 1150 °C for 2 h in vacuum (10−3 Torr), the powder was transformed into Cr3C2, while the crystalline Cr2O3 was transformed into a mixture of Cr7C3 and Cr3C2. The examinations by x-ray diffraction, transmission electron microscopy, and energy dispersive spectroscopy confirmed the transformation of the nano-sized Cr3C2 powders. The results of thermogravimetry and differential thermal analysis indicated that the transformation temperature was ∼1089 °C for amorphous Cr2O3 and ∼1128 °C for crystalline Cr2O3.
Type
journal article