The reaction mechanism of SiC synthesis on SWCNTs surface

Carbon nanotube reinforced aluminum matrix composites (CNTs/AMCs) exhibit superior mechanical properties and high corrosion resistance. Surface modification of CNTs with metal or carbide coatings can effectively enhance interfacial bonding and the resulting mechanical performance, making these composites highly promising for aerospace and transportation applications. In this study, SWCNTs-SiC composite powders with a unique "bud-stalk" structure were synthesized via an in-situ reaction using single-walled carbon nanotubes (SWCNTs) and nano-Si powder as precursors, with octylphenol polyoxyethylene ether-10 (OP-10) as the surfactant. The influence of SWCNTs-to-Si molar ratios (1:1, 2:1, 4:1) on the phase composition, microstructure, and interfacial characteristics of the composite powders was systematically investigated. The results indicate that the initial reaction temperature is approximately 1040 °C. Complete conversion of elemental Si was achieved at 1250 °C, yielding β-SiC as the primary phase. Within the experimental range, the modified SWCNTs maintained excellent structural integrity. While increasing the Si content elevated the yield of SiC, excessive Si led to increased cluster size and severe aggregation of SiC particles. Considering both the modification degree and structural damage, the composite powder prepared at a 2:1 molar ratio exhibited an optimal balance, with an ID/IG ratio of 0.082. Based on the experimental findings, the in-situ reaction is inferred to proceed through synergistic solid-solid and gas-solid mechanisms. Si atoms preferentially nucleate at the defect sites of SWCNTs and grow via epitaxial stacking along the 111 crystal planes, eventually forming a continuous SiC layer. The synthesized SWCNTs-SiC composite powders serve as promising candidate structures for interfacial regulation in CNTs/AMCs, demonstrating significant potential for practical applications.