Additive Manufacturing of High and Ultra-High Temperature Ceramics and Composites: Processing, Characterization and Testing: Extrusion-based Additive Manufacturing Methods
Sponsored by: ACerS Engineering Ceramics Division
Program Organizers: Corson Cramer, Oak Ridge National Laboratory; Greg Hilmas, Missouri University of Science and Technology; Lisa Rueschhoff, Air Force Research Laboratory
Wednesday 2:00 PM
October 20, 2021
Room: A111
Location: Greater Columbus Convention Center
Session Chair: Greg Hilmas, Missouri University of Science and Technology
2:00 PM
Additive Manufacturing Of ZrB2-SiC Heat Exchanger Geometries by Ceramic on Demand Extrusion: Nicholas Timme1; Marharyta Lakusta1; Jeremy Watts1; Gregory Hilmas1; William Fahrenholtz1; Ming Leu1; David Lipke1; 1Missouri University of Science and Technology
Zirconium diboride (ZrB2) belongs to a group of materials known as ultra-high temperature ceramics (UHTCs), which are characterized by melting temperatures exceeding 3000°C. Incorporation of silicon carbide (SiC) with ZrB2 has shown to increase the strength, fracture toughness, and oxidation resistance. These materials are being investigated to produce heat exchangers intended for use in supercritical carbon dioxide (CO2) Brayton cycles operating at up to 1100°C and 250 bar because of their high thermal stability and thermal conductivity at this temperature.In the present work, a ZrB2-SiC paste was developed for dual-extrusion in the Ceramic on Demand Extrusion (CODE) process with an organic fugitive material. This process was used to produce geometries with continuous through channels, which were then pressurelessly densified to greater than 95% theoretical density. This presentation will examine the development and characterization of microchannel-style heat exchanger geometries produced via CODE and the constituent materials used for their manufacturing.
2:20 PM
Ceramic On-demand Extrusion (CODE) of Functionally Graded ZrB2-Mo: Austin Martin1; Sachin Choudhary1; Jeremy Watts1; Gregory Hilmas1; Ming Leu1; Tieshu Huang2; 1Missouri University of Science and Technology; 2NNSA's Kansas City National Security Campus
Functionally graded materials (FGMs) involve the spatial variation of chemical composition or structure, typically to achieve an optimization of material properties. Ultra-high temperature ceramics (UHTCs) are classified as materials that have melting points above 3000°C, and although UHTCs can retain high strengths and oxidation resistance at high temperatures (>1500°C), these materials are typically brittle and therefore may benefit from underlying ductile or higher fracture toughness substructure. Molybdenum (Mo) alloys such as Mo-Si-B or Ti-Zr-Mo (TZM) are high temperature (~1000°C), creep resistant alloys which have improved fracture toughness (RT ~10 MPa∙√m or greater) compared to pure zirconium diboride (ZrB2). In this research, an active mixer equipped with dual extruders was used to adjust composition throughout printing to produce ZrB2-Mo graded structures. ZrB2 and Mo paste development and the respective optimizations for co-printing will be reviewed. Finally, chemical and processing constraints on co-printing, co-shrinkage, and cofiring of ZrB2-Mo FGMs will be examined.
2:40 PM
Additive Manufacturing of Aqueous Based Silicon Nitride Suspensions via Direct Writing: William Costakis1; Connor Wyckoff1; Lisa Rueschhoff1; 1Air Force Research Labs
Direct ink writing is an additive manufacturing technique that has the ability to yield novel architected cellular structures that demonstrate high specific mechanical properties and increased toughness over their bulk counterparts. The cost-effective nature of this process and control of material deposition allows for the production of tunable ceramic systems that can exhibit a wide range of properties making them ideal for lightweight structural and thermal management components. Here, we present the work of DIW of silicon nitride using aqueous-based slurry inks. The inks were developed and tailored based on previous suspensions developed for room temperature injection molding. Characterization of the ink rheological properties and the final sintered mechanical properties of printed samples will be presented.