Dr. Akbulut is an Associate Professor at Sabancı University, Istanbul. She received her B.S. in Materials Science and Engineering at Sabancı University (2004). Her PhD from MIT focused on cost-effective fabrication of biomolecular devices and surface science (2009). She continued her studies as a post-doctoral fellow at Harvard University on developing tools for resource-limited settings (2009–2012). Dr. Akbulut’s main research interests are silicone-based composites and rheology modifiers for cement and 3D printing industry. Her spinoff, Surgitate (2014), designs and fabricates of tactile surgical training platforms.
PCE-based additives enable the formulation of highly-loaded, high-performance ceramic inks for extrusion printing
Additive manufacturing (AM) has shown its potential to print “functionality” along with “form”. Fabrication of ceramic objects/features has become one of the goals of AM since ceramics are hard to process with conventional methods. The capabilities of AM, however, are restricted by the availability of ceramics inks. Current formulations are highly-loaded suspensions of ceramic particles (at amounts 65–75 wt. % for direct-writing, 5–20 wt. % for ink-jet printing). The stability and viscosity-control of these suspensions are sustained through combinations of additives in large amounts (5–30 wt. %). There are two inter-related problems associated with these formulations: i) they utilize linear polyelectrolytes as dispersants and rely on electrostatic repulsion-based stability—the key role of steric hindrance for stability and rheological control of suspensions is ignored, ii) non-optimized chemicals rise a need for the use of many additives in high amounts leading to harder dimensional control and more defects. This conspicuous lack of systematic strategy for designing ceramic inks hinders the ultimate potential of AM. On the other hand, controlling the rheological response of highly loaded suspensions is a well-studied problem in the cement industry and there are several poly(carboxylate ether)(PCE)-based solutions in the market. Although, AM also tackles with the same problem, until now, unlike the cement industry, failed to offer or adopt a much-needed universal solution.
Here, I will be describing the particle-specific design of PCE-based single additives that can offer both stability and viscosity-control in extrusion-printing of ceramic inks. I will be underscoring the choice of co-monomers and side-chain density for three different particle systems—iron oxide, alumina, and zirconia while demonstrating the clear difference between the performance of optimized and non-optimized inks. Through utilizing less than 1,5 wt.% PCE-based additives in ceramic inks, we are reaching almost theoretical loadings and these formulations can provide i) tighter dimensional control, ii) lower sintering temperatures, and iii) elimination of other additives and hence the burn-out step. There is a clear market for PCEs in AM.