A Freeze-form Extrusion Fabrication (FEF) process capable of making three-dimensional (3D) parts and structures with graded composite materials is presented in this paper. The process development includes the design and manufacture of a gantry machine with a triple-extruder mechanism and the associated electronics hardware and computer software for fabricating functionally graded parts from multiple aqueous pastes. A rheological behavior study with Al2O3 paste is performed to identify an efficient binder for transforming the paste into a pseudoplastic with a high yield stress. A green part is first fabricated using the triple-extruder FEF machine in a layer-by-layer manner with the desired material gradients. The green part is then freeze-dried, its binder removed through a burnout process to obtain a brown part, and the final part obtained by sintering. The final part is analyzed using energy dispersive X-ray spectroscopy (EDS) to determine its material composition. The results demonstrate that the FEF process can be used to fabricate functionally graded composite parts with pre-specified gradients.
M. Leu et al., "Freeze-Form Extrusion Fabrication of Composite Structures," Proceedings of the 22nd Annual International Solid Freeform Fabrication Symposium (2011, Austin, TX), pp. 111-124, University of Texas at Austin, Aug 2011.
22nd Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference (2011: Aug. 8-10, Austin, TX)
Mechanical and Aerospace Engineering
Materials Science and Engineering
Keywords and Phrases
3D printers; Binders; Extrusion; Sintering; Three dimensional; X ray spectroscopy; Associated electronics; Design and manufactures; Energy dispersive X ray spectroscopy; Functionally graded; Functionally graded composites; Graded composite materials; Material compositions; Rheological behaviors; Fabrication
Article - Conference proceedings
10 Aug 2011