Effects of silicon powder structure of nitriding

Effect of mechanical activation on the formation of Si3N4-SiC composite powders

“…For example, when low-defective silicon present in the nonactivated charge is nitrided, the solid-gas mechanism is the major contributor to the formation of nitride and thus leads to β-Si 3 N 4 . As the mechanical treatment of the charge becomes longer, the imperfection and dispersion of silicon increase, as shown above, and so is its evaporation rate according to [10]. As a result, α-Si 3 N 4 mainly forms in the reaction between silicon vapors and molecular nitrogen.…”

“…Mechanically induced activation not only refines powders, but also leads to defective structures so that the synthesis parameters can be reduced. The paper [10] shows that defective silicon is nitrided at much lower temperature given equal specific surface areas of the powders. Crystal defects promote the nucleation of a new phase in a solid-gas reaction and accelerate the evaporation of silica leading to the formation of Si 3 N 4 in a gas phase.…”