Friction and wear behaviour of additively manufactured continuous carbon fibre reinforced PA6 composites

In the present work, continuous carbon fibre (CCF) reinforced polyamide 6 (PA6) composites were fabricated using the Fused Filament Fabrication (FFF) 3D printing technique. The sliding friction and wear behaviour of the printed CCF/PA6 composites was investigated as a function of varying fibre orientations (i.e. normal, parallel, and anti-parallel) and layer deposition directions (i.e. parallel and perpendicular) with respect to the sliding direction. It emerged that fibre orientation played a key role in determining the wear resistance of 3D printed composites. Severe fibre breakage was observed when the orientation of fibre was in normal direction against the sliding direction, associated with a higher wear rate than that obtained in parallel or anti-parallel direction. To better understand the effects of voids on wear mechanism, tribo-tests were further carried out with the specimens that underwent compression moulding (CM) post-treatment process. The results confirmed that the internal defects could cause adverse impacts on wear performance, depending on the fibre orientations. In particular, it was found that fibre distribution, as well as the fibre/matrix interface within the filament, was the crucial parameter affecting the overall tribological performance of the printed structures. The findings add to our understanding of designing and fabricating wear-resistant polymer composites using 3D printing technologies.