Powder characteristics, microstructure and properties of graphite platelet reinforced Poly Ether Ether Ketone composites in High Temperature Laser Sintering (HT-LS)

This is the author's accepted manuscript. The final published article is avilable from the publisher via DOI: 10.1016/j.matdes.2015.09.094Copyright © 2015 Elsevier Ltd. All rights reserved.The properties of graphite platelet reinforced Poly Ether Ether Ketone (PEEK/GP) composites from powder to laser sintered parts were investigated in this study. The flowability, particle size and laser absorption characteristics of PEEK/GP powders with various graphite loadings were studied. It was found that the addition of graphite improved laser absorption; however, the flowability of powder was reduced. Micro-CT scanning was used to study the distribution, dispersion and the orientation of graphite platelets as well as the porosity and maximum pore size of laser sintered PEEK/GP composites. The graphite platelets were observed to be distributed evenly in the structure without significant agglomeration. Most of the graphite had their in-plane surface orientated in the X-Y plane of fabrication, which increased the tensile strength of the composites incorporating 5. wt.% graphite. The investigation also demonstrated that the porosity and maximum pore size increased with increasing amounts of graphite. A significant increase in porosity and pore size was found in PEEK/GP composites with 7.5. wt.% graphite, and it is believed to be responsible for the drop in tensile strength. DMA analysis showed no reduction of the damping properties in the composites incorporating up to 5. wt.% graphite, whereas the composites with 7.5. wt.% graphite showed increased stiffness