Novel nanometer-level uniform amorphous carbon coating for boron powders   by direct pyrolysis of coronene without solvent
  A 3 nm coronene coating and a 4 nm amorphous carbon coating with uniform shell-core encapsulation structure for nanosized boron (B) powders are formed by a simple process, where coronene is directly mixing with boron particles without a solvent, and heated at 520 {\deg}C for 1 h or at 630 {\deg}C for 3 h in a vacuum-sealed silica tube. Coronene has a melting point lower than its decomposition temperature, which enables liquid coronene to cover B particles by liquid diffusion and penetration without the need for a solvent. The diffusion and penetration of coronene can extend to the boundaries of particles and inside agglomerated nanoparticles to form a complete shell-core encapsulated structure. As the temperature is increased, thermal decomposition of coronene on the B particles results in the formation of a uniform amorphous carbon coating layer. This novel and simple nanometer-level uniform amorphous carbon coating method is possibly applied to many other powders, thus it has potential applications in many fields with low cost. 
ShuJun Ye, MingHui Song, and Hiroaki Kumakura
cond-mat.mtrl-sci