2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Materials: Ceramics, Glasses
Program Organizers: Joseph Beaman, University of Texas at Austin
Monday 1:30 PM
August 14, 2023
Room: 616 AB
Location: Hilton Austin
Session Chair: Desiderio Kovar, University of Texas at Austin
1:30 PM
Effect of Binder Content on Ceramic Paste for Additively Manufactured Parts via Ceramic On-demand Extrusion: Abid Hasan Rafi1; Marharyta Lakusta1; David Lipke1; Jeremy Lee Watts1; Greg Hilmas1; Ming C. Leu1; 1Missouri University of Science and Technology
Ceramic On-Demand Extrusion (CODE) is an extrusion-based process to produce highly dense sintered ceramic components from aqueous pastes with low binder content. This study examines the effects of the binder amount addition and dispersion on paste printability and residual porosity of sintered parts. An aqueous paste made of ZrB2/SiC (70/30 by volume) powder with ~45 vol% solid loadings and methylcellulose binder is used. When the binder is directly added as a powder to the paste, a notable reduction in the relative density of post-processed samples is observed when the binder amount increases. This work also reports the effects of alternative homogenization procedures, including using filtered dissolved binder solutions on sintered density and pore size distributions. This study is significant for extrusion-based ceramic additive manufacturing, particularly fabricating parts with microscale features such as microchannels in compact heat exchangers, where the frequency of large pores (relative to feature sizes) must be controlled.
1:50 PM
Origami Robocasting of High-density Ceramic Structures with Slurry-based Inks: Kayla Blalack1; Lilly Balderson1; Tao Sun1; 1University of Virginia
Robocasting of ceramics offers a simple process, yet has limitations in geometrical freedom due to the need for external supports. Previous research explored the potential of origami robocasting, which involves printing a flexible green body that can be reshaped. However, the ink formulations used before mainly rely on preceramic polymers with good elasticity, which are often limited to silicon-based ceramics and may result in large shrinkage and/or low density in the final part. In our work, a slurry-based ink with flexible polymeric binders and a wide range of material options is used for robocasting origami-folded parts. Our results show that sintered alumina produced with this ink exhibited high density and moderate shrinkage while retaining manipulated shapes without any adverse deformation. The use of this ink for ceramic origami opens up many possibilities for creating advanced geometries in various applications, including aerospace components, biomedical scaffolds, and precise catalyst supports.
2:10 PM Cancelled
The Impact of the Printed Part Size on the Shrinkage and Density in Binder Jetting Additive Manufacturing of Ceramics Powder: Suleiman Obeidat1; Chris Smith1; Junkun Ma1; 1Sam Houston State University
Ceramics particles are used to investigate the effect of the part size on the shrinkage percentage, the apparent, and the relative density of the printed part in the Binder Jetting 3D printing process. Four different shapes including cylinders, rectangular blocks, cones, and spheres of different sizes are printed at 100 %, 75%, and 50 % core saturation limits at 0 and 10 second delay using a binder jetting 3D printer. After the fabrication process, the parts are de-powdered and dried, the binder is cured at 35°C for 6- 8 hours then the parts are sintered. The shrinkage percentage, the apparent, and the relative density of the printed parts are calculated after the sintering process for each geometry at two different sizes. We use ceramics powder of 50% crystalline silica (quartz), 25% kaolinite, and 25% of potassium feldspar. The binder consists of 8% Diethylene glycol, 2% Surfactant, and 90 % water.
2:30 PM
Detecting the Onset of Flash Event in Selective Laser Flash Sintering: Joey Zamora1; Joseph Beaman1; Desiderio Kovar1; 1University of Texas at Austin
Selective laser flash sintering (SLFS) is proposed as a method for directly additively manufacturing ceramics without the need for a polymeric binder. Understanding the onset of the flash event is essential in SLFS because it is necessary to interrupt the flash before thermal runaway occurs. Successful development of a non-contact method for detecting the onset of SLFS is needed to allow a repeatable additive manufacturing process. A high-speed camera is considered in this research for its ultra-high frame rate and ability to measure temperatures from light emission from the sample surface. Experiments are conducted using alternating electric fields in the SLFS system to determine the sensitivity of this technique for detecting the onset of SLFS.
2:50 PM
Open Loop Control of Selective Laser Flash Sintering of Ceramics: David Khanan1; Desiderio Kovar1; Joseph Beaman1; 1University of Texas Austin
A goal for selective laser flash sintering (SLFS) is the production of ceramic parts with complex shapes and without the addition of a polymer binder to the powder. During the SLFS process, an electric field is passed through the build surface while a laser scans at high speeds to heat the powder. The combination of the large electric field and localized heating from the laser activates carriers in the scanned region and this produces current flow. The resulting Joule heating produces further heating of the powder that bonds the particles at the contact points. A variety of tests were conducted with a DC electric field that was actively controlled to determine conditions that produce localized flash sintering. The current across the sample was measured in situ and variable electric fields and laser parameters were tested. Experiments were also conducted with an AC electric field.
3:10 PM Break
3:40 PM
An Ultrasonic Technique to Determine the Onset of Localized Sintering in Additive Manufactured Ceramics: Christina Nissen1; Arturo Hernandez-Barreto1; Joseph Beaman1; Desiderio Kovar1; 1University of Texas at Austin
Detecting the onset of sintering non-destructively is challenging because visible changes to the powder particle morphology may be too subtle to observe directly. One material property that is highly sensitive to even small changes in particle morphology is the Young’s modulus. Here we investigate the use of an ultrasonic laser system to measure the local Young’s modulus from the surface acoustic wave speed. Time-of-flight measurements are made on control samples that were partially sintered at different temperatures. Excellent correlations were found on these monolithic samples between the Young’s moduli determined using the ultrasonic method and established resonance method. We then test the methodology on model samples that have local regions of high density that are embedded in regions of lower density. These tests show that the laser ultrasonic technique can detect local partially sintered and sintered regions within regions of unsintered packed powder beds.
4:00 PM
Volumetric Additive Manufacturing of Glass: Dominique Porcincula1; Rebecca Walton1; Martin De Beer1; Johanna Schwartz1; Luke Myers1; Alyssa Troksa1; Drew Melchert1; Rebecca Dylla-Spears1; Maxim Shusteff1; 1Lawrence Livermore National Laboratory
Volumetric Additive Manufacturing (VAM) is a novel photopolymer additive manufacturing technique that allows for the all-in-one fabrication of parts without the need for support material, in geometries not available in other AM techniques, and with smooth surfaces, which minimize the need for post-processing procedures, such as polishing. While previous work has successfully demonstrated fabrication of glass micro-optics using the VAM technique, limitations in resin formulation have prevented fabrication of parts with cross-sections larger than a few square millimeters. Here, we report on our progress in formulating a glass photopolymer resin that allows for fabrication of parts with cross-sections in the realm of square centimeters, in addition to our work in creating various glass resins with varying refractive indices.This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 within the LDRD 22-ERD-012. LLNL-ABS-847039.
4:20 PM
Manufacturability of Custom Shape-conforming Battery Components using VPP: Bharat Yelamanchi1; Sina Bakhtar Chavari1; Alexis Maurel2; Ana Martinez2; Cameroun Sherrard3; Eric MacDonald2; Pedro Cortes1; 1Youngstown State University; 2The University of Texas at El Paso; 3Marshall NASA
The rise of miniature electronics has spurred the need to develop custom power sources, especially batteries with microscale and aesthetic diversity. Tape casting, the conventional manufacturing method falls short as it can handle only large sizes and restricted form factors. This proves to be a serious constraint in the design of the end components that house such batteries especially when considering applications ranging from the handheld smart devices to NASA's human missions in space. This need is very efficiently catered for by the Vat photopolymerization (VPP). In this presentation, the manufacturability of metal collectors and electrodes using different materials and designs, their electrochemical performance and mechanical stability will be discussed. The challenges in process development and optimization of such electrodes and collectors including their metal-ceramic interface will also be discussed.
4:40 PM
Control of Track Morphology in Digital Glass Forming: Edward Kinzel1; Nicholas Capps1; Jonathan Goldstein2; Robert Landers1; 1University of Notre Dame; 2Air Force Research Laboratory
Digital Glass Forming involves locally heating a glass filament using a laser while it is continuously fed relative to the workpiece. This enables precise control of the viscosity of the molten region. The viscous melt pool is deformed by forces from the filament and workpiece. This paper investigates the relationships between the input parameters, laser power, feed rate, and scan speed, with the resulting track morphology. Tracks are used to build larger, more complex structures. By underfeeding the filament relative to the table scan speed, the glass is locally drawn to produce tracks with significantly smaller cross-sectional areas than the feedstock material. This technique allows for the production of arbitrary geometries and surface features using a smaller equivalent diameter than the input feedstock. The paper explores the available process zone for this underfed deposition mode as well as the limitations of this method.