Preparation of high purity nano-silicon powders by direct current arc plasma evaporation method

Direct current arc plasma evaporation method was used in this paper for the industrial preparation of high purity and highly-dispersed nano-silicon powders and the development its high-tech nano products. The influence of cathode current, filling pressure, pressure ratio of Hydrogen to Argon (PH2/PAr) on the particle size and the yield of nano-silicon powders was studied by orthogonal design method in experiment. The evaporation mechanism was also discussed in this paper. The results showed that high purity of 99.93 wt% was achieved with near spherical shape and cubic crystal structure. The average particle size of nano-silicon powders produced in the process in this paper ranged from 35 nm to 63 nm with the yield of 9.2 g h−1-175.2 g h−1. The mechanism of silicon powders evaporation was discussed in the paper, which led to the findings of high yield attributed to the co-existence of molecular evaporation and boiling evaporation coexist.