Prediction and experimental verification of tribological performance of 3D-printed PEEK composite sliding layers with target fiber orientation designs

Abstract

This study explores the morphology and tribological properties of 3D-printed composite sliding layers using fused filament fabrication (FFF). Morphology analysis confirms uniform carbon fiber dispersion and strong fiber alignment in the printing direction. Tensile shear strength tests reveal significantly improved adhesion with a Vestamelt Hylink (VH) adhesive layer compared to samples without it. Experimental results of the friction and wear tests reveal that the coefficient of friction (COF) and specific wear rate (w_s) of the sliding layers show a strong dependence on the fiber orientation. Samples with fibers aligned parallel (P) to the sliding direction exhibited the lowest COF and wear rate at 400 N m/s, with values of 0.16 and 0.24 × 10⁻⁶ mm³/(Nm), respectively. Similarly, anti-parallel (AP) fiber orientation resulted in a COF of 0.18 and a wear rate of 0.28 × 10⁻⁶ mm³/(Nm). In contrast, samples with fibers oriented normal (N) to the sliding direction showed the highest values, with a COF of 0.32 and a wear rate of 0.99 × 10⁻⁶ mm³/(Nm), where fibers are more likely to break and increase matrix wear. A predictive model accurately estimates COF and w_s based on fiber alignment and F_N·v-products, validated through experimental results. These findings highlight the critical role of fiber orientation in designing fiber-reinforced components for optimizing the tribological properties of polymer composites/steel sliding systems.