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.

Meeting Name

22nd Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference (2011: Aug. 8-10, Austin, TX)


Mechanical and Aerospace Engineering

Second Department

Materials Science and Engineering


This project is funded by NSF grant #CMMI-0856419 with matching support from Boeing Company through the Center for Aerospace Manufacturing Technologies at the Missouri University of Science and Technology, and by the Air Force Research Laboratory through Universal Technology Corporation (Contract #10-S568-0094-01-C1).

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

Document Type

Article - Conference proceedings

Document Version

Final Version

File Type




Publication Date

10 Aug 2011