Electron microscopy in assessing raw materials and products in the plasma synthesis of chromium compounds containing boron and carbon

The initial powders in plasma synthesis (chromium, its oxide and chloride, and boron), the micro- and nanopowders of chromium boride and carbonitride produced, and the accompanying pyrolytic boron and carbon are investigated by means of transmission and scanning electron microscopes. In the analysis of the powders and industrial micropowders of chromium boride and carbide, transmission electron microscopy yields complete information regarding the shape and size of the particles and their disperse composition. In the analysis of the nanopowders, transmission electron microscopy permits the visualization of individual particles, determination of their linear dimensions, and confirmation of their near-spherical shape. Scanning electron microscopy provides information regarding the nanoparticles’ tendency to aggregate and permits investigation of the ensemble of nanoparticles, as well as individual nanoparticles, with refinement of their dimensional range. It confirms the geometric shape of the particles and permits the proposal and discussion of mechanisms of nanoparticle formation. The distinguishing feature of the pyrolytic boron and carbon nanoparticles is their ability to form microaggregates (200–400 and 150–200 nm, respectively) consisting of particles in the range 10–40 nm. © 2014, Allerton Press, Inc.