Combustion synthesis of SiC/Al2O3 composite powders with SiC nanowires and their growth mechanism

SiC/Al₂O₃ composite powders with SiC nanowires were synthesized using a one-step combustion synthesis method taking silica fume (SiO₂), aluminum powder (Al) and carbon black (CB) as raw materials, while ferrocene (C₁₀H₁₀Fe) was used as the catalyst. The calculated results for the relationship between the equilibrium phase and temperature of the Al–SiO₂–C system show that SiC and Al₂O₃ are the only equilibrium phases in the system. In addition, the effects of C₁₀H₁₀Fe on the combustion synthesis process and products were studied. It was found that with increasing catalyst content, the amount of residual Si in the products first decreases and then increases, the combustion temperature first increases and then decreases, and the nanowire content continues to increase. For an optimal amount of C₁₀H₁₀Fe of 0.75 wt%, almost no residual Si is observed in the product, while the combustion temperature (T_c) is high (2104 K), the SiC nanowire content is relatively high, and the nanowire aspect ratio is large. In addition, two growth mechanism models for SiC nanowires: VS and VLS were validated.