Hybrid additive-subtractive manufacturing of surface-modified CF/PEEK porous implants with high-low temperature assistance.

Abstract

This study developed an integrated additive-subtractive hybrid manufacturing strategy for fabricating surface-modified carbon fiber-reinforced polyetheretherketone (CF/PEEK) porous implants. The approach synergistically combined 3D printing with precision milling, assisted by high-temperature air during printing and low-temperature air during milling. CF are first modified via electrochemical oxidation and silane coupling agent treatment to improve interfacial bonding with the PEEK matrix. Porous implants with various lattice structures (Spherical, Diagonal, Diamond, Cubic) are fabricated. The results demonstrated that CF surface modification significantly improved interfacial bonding, increasing the interlaminar shear strength (ILSS) by 32%. The low-temperature air-assisted milling process effectively suppressed plastic deformation and fiber pull-out, transitioning the material removal mechanism to micro-brittle fracture and thereby reducing surface roughness. While the addition of CF enhanced the mechanical properties (compression strength, Vickers hardness) and tribological performance (lower friction coefficient and wear rate) of PEEK, it also increased the surface roughness and hydrophobicity of the composites. Milling effectively improved the surface quality of 3D printed parts but slightly reduced the compression strength of porous structures due to the cutting of load-bearing struts. This material-structure-process-performance integrated strategy provides a viable technical pathway for manufacturing high-performance, personalized bone implants.