Mechanical property of powder bed fusion printed carbon fiber reinforced polyetheretherketone and enhanced interlayer strength by post-processing

Additive Manufacturing (AM) of carbon fiber reinforced polyetheretherketone (CF/PEEK) composites with excellent performance by Powder Bed Fusion (PBF) has great potential in the applications where high strength and high service temperature are required. However, the reinforcement mechanisms of CF/PEEK composites based on the PBF process are complex and show significant differences from traditional processing methods. In this paper, the mechanical properties of CF/PEEK prepared by PBF were investigated. The results showed that its X-axis tensile strength and modulus were approximately equal to or a bit lower than the theoretical value with randomly distributed CF, but much lower than the theoretical value with unidirectional distribution of CF in composites. Meanwhile, mechanical strength anisotropy was observed. The composites' Y-axis tensile strength was slightly lower than X-axis, and the lowest strength existed in Z-axis. To improve the weak Z-axis strength, post-processing of annealing and solvent-induced crystallization were carried out, and the Z-axis tensile strength of post-processed parts reached 50 MPa, which was 62% higher than untreated samples. Consequently, suitable CF and proper post- processing for AM of high strength CF/PEEK were proposed, which would promote the industrial application of this technology. Highlights: The effect of CF on mechanical property of CF/PEEK prepared by PBF were studied. The optimal CF for PBF of high strength CF/PEEK were obtained. The post-processing method for improving the Z-axis strength were proposed. CF/PEEK with comprehensive mechanical property was successfully prepared by PBF.