Paper Number
AC20
Session
Additive Manufacturing and Composites
Title
Rheological behavior and process monitoring of highly filled direct ink write pastes
Presentation Date and Time
October 13, 2022 (Thursday) 9:25
Track / Room
Track 7 / Ontario
Authors
- Kopatz, Jessica W. (Sandia National Laboratories)
- Reinholtz, Derek (Sandia National Laboratories)
- Cazares, Adolfo (Texas Tech University)
- Leonard, Jonathan (Sandia National Laboratories)
- Tappan, Alexander S. (Sandia National Laboratories)
- Cook, Adam W. (Sandia National Laboratories)
- Grillet, Anne M. (Sandia National Laboratories)
Author and Affiliation Lines
Jessica W. Kopatz, Derek Reinholtz, Adolfo Cazares, Jonathan Leonard, Alexander S. Tappan, Adam W. Cook and Anne M. Grillet
Sandia National Laboratories, Albuquerque, NM 87123
Speaker / Presenter
Kopatz, Jessica W.
Keywords
additive manufacturing; composite rheology
Text of Abstract
Direct ink write is a powerful additive manufacturing tool that allows for flexibility in creating custom-designed and reproducible hardware by depositing an “ink” onto a substrate in a desired pattern via extrusion through a syringe. Highly-filled dense inks often contain trapped air within the ink or particle aggregates that cause undesirable clogging during extrusion. These defects can be detrimental to the final material properties of the printed part. The goals of this work are to understand the effects of filler morphology on ink rheology and identify the viability of using pressure monitoring during extrusion to detect printing defects. The custom-built direct ink write system used for this work has pressure monitors incorporated both at the top of the syringe and just before the nozzle. To design and print highly-filled inks, we need to understand the effect of filler morphology, size, loading, and packing fraction on the resin rheology and printability. Various filler particles and volume loadings of particles were dispersed in silicone resin to investigate the change in zero-shear viscosity, shear-thinning behavior, and plateau modulus. The extrusion pressure was measured at several volume loadings to determine the highest attainable volume loading for printable resins as a function of particle morphology. To determine the sensitivity of the pressure measurement to the presence of aggregates in the inks, we incorporated engineered defects from 165 to 1000 microns in size in a commercial silicone ink. Extrusion of the engineered defects is correlated to both pressure measurements and quality of the print. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.