Ultra-high-temperature ceramics are being investigated for future use in aerospace applications due to their superior thermo-mechanical properties, as well as their oxidation resistance, at temperatures above 2000⁰C. However, their brittleness makes them susceptible to thermal shock failure. As graded composites, components fabricated as functionally-graded materials (FGMs) can combine the superior properties of ceramics with the toughness of an underlying refractory metal. This paper discusses the grading of two materials through the use of a Freeze-form Extrusion Fabrication (FEF) system to build FGM parts consisting of zirconium carbide (ZrC) and tungsten (W). Aqueous-based colloidal suspensions of ZrC and W were developed and utilized in the FEF process to fabricate test bars graded from 100%ZrC to 50%W-50%ZrC (volume percent). After FEF processing, the test bars were co-sintered at 2300⁰C and characterized to determine their resulting density and microstructure. Four-point bending tests were performed to assess the flexural strength of the test bars made using the FEF process, compared to that prepared using conventional powder processing and isostatic pressing techniques, for five distinct ZrC-W compositions. Scanning electron microscopy (SEM) was used to examine the inner structure of composite parts built using the FEF process.

Meeting Name

23rd Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference (2012: Aug. 6-8, Austin, TX)


Materials Science and Engineering

Second Department

Mechanical and Aerospace Engineering


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

Keywords and Phrases

3D printers; Aerospace applications; Carbides; Ceramic materials; Extrusion; Fabrication; Fracture mechanics; Functionally graded materials; Grading; Mechanical properties; Scanning electron microscopy; Sintering; Suspensions (fluids); Tungsten; Colloidal suspensions; Four-point bending test; Graded composites; Isostatic pressing; Powder processing; Thermomechanical properties; Ultra-high-temperature ceramics; Zirconium carbide

Document Type

Article - Conference proceedings

Document Version

Final Version

File Type




Publication Date

08 Aug 2012