Interface design of carbon fiber composites by fabricating interlocked carbon nanotubes-silicon nitride nanowires

Prominent interfacial bonding can significantly improve the stress transfer efficiency between carbon fibers and matrix, which is the basis of efficient and long-term application of composites. In this paper, a bicomponent collaborative strategy was proposed to fully utilize the advantages of silicon nitride nanowires (SNs) and carbon nanotubes (CNTs) to optimize the interfacial strength of carbon fiber modified double matrix composites (CD), in which the double matrix was represented by polymers-hydroxyapatite and pyrocarbon-hydroxyapatite. The microstructure displayed that SNs were randomly distributed inside CD and completely wrapped by CNTs, which combined to form an interlocking structure. The mechanical and friction behavior of modified and unmodified composites was investigated. The compression strength and shear strength of CNTs-SNs modified carbon fiber/polymers-hydroxyapatite composites were 110 ± 2.39 MPa and 56 ± 1.13 MPa, displaying an increment of 69% and 87%. The wear rate was 0.4 × 10⁻¹⁴ ± 0.008 m³ N⁻¹ m⁻¹, exhibiting a 61% decline. The fracture morphologies were observed to analyze the strengthening mechanism. Interlocked CNTs-SNs could strengthen the effective bonding of fiber/matrix interface and SNs/matrix interface, provide lots of nucleation sites for the matrix, and enhance the matrix cohesion. The enhancement was further verified by a 56% increase in the compression strength (237 ± 4.67 MPa), a 235% increase in the shear strength (77 ± 1.53 MPa), a 78% decrease in wear rate (0.38 × 10⁻¹³ ± 0.011 m³ N⁻¹ m⁻¹) of CNTs-SNs modified carbon fiber/pyrocarbon-hydroxyapatite composites, indicating that CNTs-SNs played an indispensable role in making CD possess brilliant mechanical and biological friction properties.