Low-temperature grafting of carbon nanotubes on carbon fibers using a bimetallic floating catalyst

• We report a new low-temperature processing route to grow CNTs on CF surfaces without mechanically degrading the CFs using a Ni–Fe bimetallic floating catalyst system.
• The degradation mechanism of mechanical properties of CFs experiencing the catalytic growth of CNTs on their surface through high-temperature CVD was revealed using microstructural analysis.
• The degradation mechanism was the diffusion of catalyst nanoparticles into CFs which makes microvoids and stress-concentrator near the surface of CFs.

The degradation mechanism of CFs experiencing the catalytic growth of CNTs on their surface through high-temperature CVD was revealed using microstructural analysis. Catalysts nanoparticles, if their energy was high enough to diffuse into CFs, generated micro-voids in CFs and reduced their tensile strength. Herein, we report a new low-temperature processing route to grow CNTs on CF surfaces without mechanically degrading the CFs. The use of a Ni–Fe bimetallic catalyst was key to achieving the growth of CNTs at low temperature, e.g., 500 °C. Catalyst diffusion into the CFs during CVD was inhibited at this temperature, which facilitated uniform growth of CNTs on only the CF surfaces and minimized internal structural changes of the CFs.

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