Comprehending Extrusion Rheology for Additive Manufacturing of Inks and Colloidal Systems (CERAMICS)
Abstract
Ceramics and ceramic research play an important role across the DoD. Materials like B4C are used in body armor and high dielectric c eramics can be leveraged in RF materials. From small electrical components to IR and RF apertures, the size of the ceramic parts var y, but are all critical to mission success. One of the biggest challenges with ceramics however is their manufacturing cost. Ceramic s require high temperatures for manufacturing, and then often require extensive machining to achieve a desired geometry. This is par ticularly true in optical materials, as the density needs to be almost 100%, while the surface needs to be completely flat, so furth er sintering and polishing are essential. Machining becomes an even greater challenge when geometries are not flat and excess materi al needs be removed in bulk, leading to major loss in materials. The benefit of using a near net shape fabrication technique would a llow for the development of ceramic parts as designed and reduce the burdenon machining and subtractive manufacturing for specific g eometries.Additive manufacturing (AM) has provided advantages for near net shape fabrication of polymers and metals, but while ceram ic AM is not new, it is the least mature method, especially with technical ceramics. One of the most common techniques for ceramics is vat photopolymerization. It has arguably made the most advancements in recent years with respect to ceramics manufacturing, yet i t is still restricted by part size and materials. Paste extrusion does not have those same limitations however. With the ability to fabricate parts with a greater cross-section, as well as more design freedom to incorporate a wider range of materials, a paste base d AM process provides multiple advantages for ceramic processing.Paste development is not trivial, as the rheology needs to be both shear thinning, but maintain a high static yield point so that the paste does not lose shape as layers are printed on top of it. The behavior of the paste varies depending on a range of properties, such as powder morphology, solids loading, pH, dispersant concentr ation, and ceramic chemistry. The proposed research will investigate how the different additives and rheology modifiers interact wit h different ceramics to better understand how to design pastes so that they can be strategically formulated based on a desired appli cation. The research will start by taking a single ceramic and investigating how its rheology changes with respect to different poly mers, pHs, and chemistries. Based on those observations and how the different additives affected the ceramics, similar recipes will be implemented with other ceramic powders, both similar and unalike, to observe how the ceramic composition impacts the paste reliab ility in an additive application. After investigating and developing different ceramic pastes for AM, they can be used to additively make graded interfaces, coatings, armor, or apertures.The ability to reliably use AM for ceramic fabrication for highly technical d esigns while being able to replicate the properties of the material via traditional fabrication methods would provide the Navy and D oD a distinct advantage with ceramic materials. The benefits are not just improved efficiency and reduced economic burden. It would also provide an avenue for more advanced concept design fabrication such as conformal body armor and graded hypersonic sensing windo ws.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2021
- Source ID
- N000142112669
Entities
People
- Collin Mcclain
Organizations
- Johns Hopkins University
- Office of Naval Research
- United States Navy