Aging mechanism of polyetheretherketone powder during layer-wise infrared radiation of high-temperature laser powder bed fusion

Variations of the properties of virgin and recycled powders are still important challenges in high-temperature laser powder bed fusion, which directly affect the processing parameters and the ultimate quality of the product. The key factor is the aging mechanism of powder during the layer-wise infrared radiation process of laser powder bed fusion. Therefore, the evolution of physico-chemical structure under different infrared radiation temperatures is thoroughly studied in this paper, and the aging mechanism is proposed for polyetheretherketone powder. On the one hand, the layer-wise infrared radiation can promote the spheroidization of particle edges and corners, and the fusion of slits inside the powder. Meanwhile, more ordered crystalline structure, smaller interplanar spacing, and reduced lattice volume emerge with the deepening of powder aging. The sintering window is widened accompanied by the disappearance of the exothermic peak. On the other hand, although the chain does not break after aging, the macromolecular has been cross-linked to form a biphenyl structure, which can directly reduce the crystallinity of polyetheretherketone powder. This research is of guiding significance for the development of anti-aging polyetheretherketone powder and the consistent powder management of laser powder bed fusion.