Functionally graded polyetheretherketone-based composites additively manufactured by material extrusion using a transition interface design method

Abstract

The addition of short carbon fibers (CFs) and glass fibers (GFs) can significantly enhance the mechanical properties of polyetheretherketone (PEEK); however, ductility is significantly reduced. Owing to the significant differences in mechanical, thermal and tribological properties of CF/GF-PEEK, PEEK-based functionally graded materials (FGMs) are promising materials for 3D printing. This paper proposes a novel method for preparing FGMs using continuous welding filaments to improve the comprehensive performance of 3D printed CF/GF-PEEK. In addition, two innovative graded interface design methods are proposed for extrusion-based 3D printing of FGMs. Furthermore, a series of 3D printing experiments were conducted to verify our design methods. The 3D-printed FGMs composed of CF/GF-PEEK composites possess excellent toughness while maintaining good mechanical properties and interlayer bonding performance. The elongation at the fracture of the FGMs prepared in this study increased by 150% compared to those of fiber reinforced PEEK composites. The overall mechanical properties of FGMs with graded interfacial layers are improved by about 12% compared with those of the FGMs without transitional structures.