Density Functional Theory Calculation and Experimental Study of Catalytic Synthesis SiC Nano Powders

Taking Si₅₅, Si₄₃M₁₂ and Si₃₇M₁₈(M=Fe, Co or Ni) cluster as models, density functional theory(DFT) was used to investigate the catalytic mechanism of Fe, Co and Ni catalysts on the formation of SiC using Si and C as starting materials. The results show that Fe, Co and Ni nano catalysts will form alloy with Si first, and then elongate the bond length of Si-Si and weaken its bond strength, finally activate Si powder. The formation of alloy is favorable to the adsorption of C atom, and then accelerate the reaction process between Si and C atoms. The catalytic performance of Fe is better than Co and Ni. On this basis, 3C-SiC nano powders were synthesized by a microwave reaction method using silicon powders and phenolic resin as raw materials, and ferric/cobalt/nickel nitrate as catalyst precursor. The effects of catalyst type, heat treatment temperature, catalyst content and holding time on the preparation of 3C-SiC were investigated. Results indicated that the addition of Fe, Co and Ni significantly decreased the synthesis temperature of 3C-SiC. Si powder can completely transform into 3C-SiC at 1100℃ for 30 min using 2.0% Fe as catalyst. In contrast, for the sample without any catalysts, corresponding temperature was as high as 1250℃. Moreover, the experiment results also indicated that the catalytic performance of Fe is better than Co and Ni, which is in consistent with the DFT calculations.